**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.7.7"
#define SQLITE_VERSION_NUMBER 3007007
#define SQLITE_SOURCE_ID      "2011-05-25 23:18:02 a4755e7088c3cc7c5ea191ce37f3950472f523ec"

/*
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version, sqlite3_sourceid
**
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
................................................................................
**
** ^The sqlite3_exec() interface runs zero or more UTF-8 encoded,
** semicolon-separate SQL statements passed into its 2nd argument,
** in the context of the [database connection] passed in as its 1st
** argument.  ^If the callback function of the 3rd argument to
** sqlite3_exec() is not NULL, then it is invoked for each result row
** coming out of the evaluated SQL statements.  ^The 4th argument to
** to sqlite3_exec() is relayed through to the 1st argument of each
** callback invocation.  ^If the callback pointer to sqlite3_exec()
** is NULL, then no callback is ever invoked and result rows are
** ignored.
**
** ^If an error occurs while evaluating the SQL statements passed into
** sqlite3_exec(), then execution of the current statement stops and
** subsequent statements are skipped.  ^If the 5th parameter to sqlite3_exec()
................................................................................
#define SQLITE_IOERR_SHMLOCK           (SQLITE_IOERR | (20<<8))
#define SQLITE_IOERR_SHMMAP            (SQLITE_IOERR | (21<<8))
#define SQLITE_IOERR_SEEK              (SQLITE_IOERR | (22<<8))
#define SQLITE_LOCKED_SHAREDCACHE      (SQLITE_LOCKED |  (1<<8))
#define SQLITE_BUSY_RECOVERY           (SQLITE_BUSY   |  (1<<8))
#define SQLITE_CANTOPEN_NOTEMPDIR      (SQLITE_CANTOPEN | (1<<8))
#define SQLITE_CORRUPT_VTAB            (SQLITE_CORRUPT | (1<<8))



/*
** CAPI3REF: Flags For File Open Operations
**
** These bit values are intended for use in the
** 3rd parameter to the [sqlite3_open_v2()] interface and
** in the 4th parameter to the [sqlite3_vfs.xOpen] method.
................................................................................
** of good-quality randomness into zOut.  The return value is
** the actual number of bytes of randomness obtained.
** The xSleep() method causes the calling thread to sleep for at
** least the number of microseconds given.  ^The xCurrentTime()
** method returns a Julian Day Number for the current date and time as
** a floating point value.
** ^The xCurrentTimeInt64() method returns, as an integer, the Julian
** Day Number multipled by 86400000 (the number of milliseconds in 
** a 24-hour day).  
** ^SQLite will use the xCurrentTimeInt64() method to get the current
** date and time if that method is available (if iVersion is 2 or 
** greater and the function pointer is not NULL) and will fall back
** to xCurrentTime() if xCurrentTimeInt64() is unavailable.
**
** ^The xSetSystemCall(), xGetSystemCall(), and xNestSystemCall() interfaces
................................................................................
** ^SQLite will never require a scratch buffer that is more than 6
** times the database page size. ^If SQLite needs needs additional
** scratch memory beyond what is provided by this configuration option, then 
** [sqlite3_malloc()] will be used to obtain the memory needed.</dd>
**
** [[SQLITE_CONFIG_PAGECACHE]] <dt>SQLITE_CONFIG_PAGECACHE</dt>
** <dd> ^This option specifies a static memory buffer that SQLite can use for
** the database page cache with the default page cache implemenation.  
** This configuration should not be used if an application-define page
** cache implementation is loaded using the SQLITE_CONFIG_PCACHE option.
** There are three arguments to this option: A pointer to 8-byte aligned
** memory, the size of each page buffer (sz), and the number of pages (N).
** The sz argument should be the size of the largest database page
** (a power of two between 512 and 32768) plus a little extra for each
** page header.  ^The page header size is 20 to 40 bytes depending on
................................................................................
** automatically deleted as soon as the database connection is closed.
**
** [[URI filenames in sqlite3_open()]] <h3>URI Filenames</h3>
**
** ^If [URI filename] interpretation is enabled, and the filename argument
** begins with "file:", then the filename is interpreted as a URI. ^URI
** filename interpretation is enabled if the [SQLITE_OPEN_URI] flag is
** is set in the fourth argument to sqlite3_open_v2(), or if it has
** been enabled globally using the [SQLITE_CONFIG_URI] option with the
** [sqlite3_config()] method or by the [SQLITE_USE_URI] compile-time option.
** As of SQLite version 3.7.7, URI filename interpretation is turned off
** by default, but future releases of SQLite might enable URI filename
** intepretation by default.  See "[URI filenames]" for additional
** information.
**
** URI filenames are parsed according to RFC 3986. ^If the URI contains an
** authority, then it must be either an empty string or the string 
** "localhost". ^If the authority is not an empty string or "localhost", an 
** error is returned to the caller. ^The fragment component of a URI, if 
** present, is ignored.
................................................................................
** [SQLITE_DONE], [SQLITE_ROW], [SQLITE_ERROR], or [SQLITE_MISUSE].
** ^With the "v2" interface, any of the other [result codes] or
** [extended result codes] might be returned as well.
**
** ^[SQLITE_BUSY] means that the database engine was unable to acquire the
** database locks it needs to do its job.  ^If the statement is a [COMMIT]
** or occurs outside of an explicit transaction, then you can retry the
** statement.  If the statement is not a [COMMIT] and occurs within a
** explicit transaction then you should rollback the transaction before
** continuing.
**
** ^[SQLITE_DONE] means that the statement has finished executing
** successfully.  sqlite3_step() should not be called again on this virtual
** machine without first calling [sqlite3_reset()] to reset the virtual
** machine back to its initial state.
................................................................................
SQLITE_API int sqlite3_column_type(sqlite3_stmt*, int iCol);
SQLITE_API sqlite3_value *sqlite3_column_value(sqlite3_stmt*, int iCol);

/*
** CAPI3REF: Destroy A Prepared Statement Object
**
** ^The sqlite3_finalize() function is called to delete a [prepared statement].
** ^If the most recent evaluation of the statement encountered no errors or
** or if the statement is never been evaluated, then sqlite3_finalize() returns
** SQLITE_OK.  ^If the most recent evaluation of statement S failed, then
** sqlite3_finalize(S) returns the appropriate [error code] or
** [extended error code].
**
** ^The sqlite3_finalize(S) routine can be called at any point during
** the life cycle of [prepared statement] S:
................................................................................
** ^The implementation is not required to provided versions of these
** routines that actually work. If the implementation does not provide working
** versions of these routines, it should at least provide stubs that always
** return true so that one does not get spurious assertion failures.
**
** ^If the argument to sqlite3_mutex_held() is a NULL pointer then
** the routine should return 1.   This seems counter-intuitive since
** clearly the mutex cannot be held if it does not exist.  But the
** the reason the mutex does not exist is because the build is not
** using mutexes.  And we do not want the assert() containing the
** call to sqlite3_mutex_held() to fail, so a non-zero return is
** the appropriate thing to do.  ^The sqlite3_mutex_notheld()
** interface should also return 1 when given a NULL pointer.
*/
#ifndef NDEBUG
................................................................................
#define SQLITE_TESTCTRL_ASSERT                  12
#define SQLITE_TESTCTRL_ALWAYS                  13
#define SQLITE_TESTCTRL_RESERVE                 14
#define SQLITE_TESTCTRL_OPTIMIZATIONS           15
#define SQLITE_TESTCTRL_ISKEYWORD               16
#define SQLITE_TESTCTRL_PGHDRSZ                 17
#define SQLITE_TESTCTRL_SCRATCHMALLOC           18

#define SQLITE_TESTCTRL_LAST                    18

/*
** CAPI3REF: SQLite Runtime Status
**
** ^This interface is used to retrieve runtime status information
** about the performance of SQLite, and optionally to reset various
** highwater marks.  ^The first argument is an integer code for
................................................................................
** stored in the cache, both pinned and unpinned.
** 
** [[the xFetch() page cache methods]]
** The xFetch() method locates a page in the cache and returns a pointer to 
** the page, or a NULL pointer.
** A "page", in this context, means a buffer of szPage bytes aligned at an
** 8-byte boundary. The page to be fetched is determined by the key. ^The
** mimimum key value is 1.  After it has been retrieved using xFetch, the page 
** is considered to be "pinned".
**
** If the requested page is already in the page cache, then the page cache
** implementation must return a pointer to the page buffer with its content
** intact.  If the requested page is not already in the cache, then the
** cache implementation should use the value of the createFlag
** parameter to help it determined what action to take:
................................................................................
SQLITE_PRIVATE int sqlite3VdbeAddOp0(Vdbe*,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp1(Vdbe*,int,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp2(Vdbe*,int,int,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp3(Vdbe*,int,int,int,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp4(Vdbe*,int,int,int,int,const char *zP4,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp4Int(Vdbe*,int,int,int,int,int);
SQLITE_PRIVATE int sqlite3VdbeAddOpList(Vdbe*, int nOp, VdbeOpList const *aOp);

SQLITE_PRIVATE void sqlite3VdbeChangeP1(Vdbe*, int addr, int P1);
SQLITE_PRIVATE void sqlite3VdbeChangeP2(Vdbe*, int addr, int P2);
SQLITE_PRIVATE void sqlite3VdbeChangeP3(Vdbe*, int addr, int P3);
SQLITE_PRIVATE void sqlite3VdbeChangeP5(Vdbe*, u8 P5);
SQLITE_PRIVATE void sqlite3VdbeJumpHere(Vdbe*, int addr);
SQLITE_PRIVATE void sqlite3VdbeChangeToNoop(Vdbe*, int addr, int N);
SQLITE_PRIVATE void sqlite3VdbeChangeP4(Vdbe*, int addr, const char *zP4, int N);
SQLITE_PRIVATE void sqlite3VdbeUsesBtree(Vdbe*, int);
SQLITE_PRIVATE VdbeOp *sqlite3VdbeGetOp(Vdbe*, int);
SQLITE_PRIVATE int sqlite3VdbeMakeLabel(Vdbe*);
SQLITE_PRIVATE void sqlite3VdbeRunOnlyOnce(Vdbe*);
SQLITE_PRIVATE void sqlite3VdbeDelete(Vdbe*);
SQLITE_PRIVATE void sqlite3VdbeDeleteObject(sqlite3*,Vdbe*);
SQLITE_PRIVATE void sqlite3VdbeMakeReady(Vdbe*,int,int,int,int,int,int);
SQLITE_PRIVATE int sqlite3VdbeFinalize(Vdbe*);
SQLITE_PRIVATE void sqlite3VdbeResolveLabel(Vdbe*, int);
SQLITE_PRIVATE int sqlite3VdbeCurrentAddr(Vdbe*);
#ifdef SQLITE_DEBUG
SQLITE_PRIVATE   int sqlite3VdbeAssertMayAbort(Vdbe *, int);
SQLITE_PRIVATE   void sqlite3VdbeTrace(Vdbe*,FILE*);
#endif
SQLITE_PRIVATE void sqlite3VdbeResetStepResult(Vdbe*);

SQLITE_PRIVATE int sqlite3VdbeReset(Vdbe*);
SQLITE_PRIVATE void sqlite3VdbeSetNumCols(Vdbe*,int);
SQLITE_PRIVATE int sqlite3VdbeSetColName(Vdbe*, int, int, const char *, void(*)(void*));
SQLITE_PRIVATE void sqlite3VdbeCountChanges(Vdbe*);
SQLITE_PRIVATE sqlite3 *sqlite3VdbeDb(Vdbe*);
SQLITE_PRIVATE void sqlite3VdbeSetSql(Vdbe*, const char *z, int n, int);
SQLITE_PRIVATE void sqlite3VdbeSwap(Vdbe*,Vdbe*);
................................................................................
** Schema objects are automatically deallocated when the last Btree that
** references them is destroyed.   The TEMP Schema is manually freed by
** sqlite3_close().
*
** A thread must be holding a mutex on the corresponding Btree in order
** to access Schema content.  This implies that the thread must also be
** holding a mutex on the sqlite3 connection pointer that owns the Btree.
** For a TEMP Schema, on the connection mutex is required.
*/
struct Schema {
  int schema_cookie;   /* Database schema version number for this file */
  int iGeneration;     /* Generation counter.  Incremented with each change */
  Hash tblHash;        /* All tables indexed by name */
  Hash idxHash;        /* All (named) indices indexed by name */
  Hash trigHash;       /* All triggers indexed by name */
................................................................................
#define SQLITE_QueryFlattener 0x01        /* Disable query flattening */
#define SQLITE_ColumnCache    0x02        /* Disable the column cache */
#define SQLITE_IndexSort      0x04        /* Disable indexes for sorting */
#define SQLITE_IndexSearch    0x08        /* Disable indexes for searching */
#define SQLITE_IndexCover     0x10        /* Disable index covering table */
#define SQLITE_GroupByOrder   0x20        /* Disable GROUPBY cover of ORDERBY */
#define SQLITE_FactorOutConst 0x40        /* Disable factoring out constants */

#define SQLITE_OptMask        0xff        /* Mask of all disablable opts */

/*
** Possible values for the sqlite.magic field.
** The numbers are obtained at random and have no special meaning, other
** than being distinct from one another.
*/
................................................................................
  u8 disableTriggers;  /* True to disable triggers */
  double nQueryLoop;   /* Estimated number of iterations of a query */

  /* Above is constant between recursions.  Below is reset before and after
  ** each recursion */

  int nVar;            /* Number of '?' variables seen in the SQL so far */
  int nVarExpr;        /* Number of used slots in apVarExpr[] */
  int nVarExprAlloc;   /* Number of allocated slots in apVarExpr[] */
  Expr **apVarExpr;    /* Pointers to :aaa and $aaaa wildcard expressions */
  Vdbe *pReprepare;    /* VM being reprepared (sqlite3Reprepare()) */
  int nAlias;          /* Number of aliased result set columns */
  int nAliasAlloc;     /* Number of allocated slots for aAlias[] */
  int *aAlias;         /* Register used to hold aliased result */
  u8 explain;          /* True if the EXPLAIN flag is found on the query */
  Token sNameToken;    /* Token with unqualified schema object name */
  Token sLastToken;    /* The last token parsed */
................................................................................
  int isMutexInit;                  /* True after mutexes are initialized */
  int isMallocInit;                 /* True after malloc is initialized */
  int isPCacheInit;                 /* True after malloc is initialized */
  sqlite3_mutex *pInitMutex;        /* Mutex used by sqlite3_initialize() */
  int nRefInitMutex;                /* Number of users of pInitMutex */
  void (*xLog)(void*,int,const char*); /* Function for logging */
  void *pLogArg;                       /* First argument to xLog() */

};

/*
** Context pointer passed down through the tree-walk.
*/
struct Walker {
  int (*xExprCallback)(Walker*, Expr*);     /* Callback for expressions */
................................................................................
SQLITE_PRIVATE int sqlite3FixExprList(DbFixer*, ExprList*);
SQLITE_PRIVATE int sqlite3FixTriggerStep(DbFixer*, TriggerStep*);
SQLITE_PRIVATE int sqlite3AtoF(const char *z, double*, int, u8);
SQLITE_PRIVATE int sqlite3GetInt32(const char *, int*);
SQLITE_PRIVATE int sqlite3Atoi(const char*);
SQLITE_PRIVATE int sqlite3Utf16ByteLen(const void *pData, int nChar);
SQLITE_PRIVATE int sqlite3Utf8CharLen(const char *pData, int nByte);
SQLITE_PRIVATE int sqlite3Utf8Read(const u8*, const u8**);

/*
** Routines to read and write variable-length integers.  These used to
** be defined locally, but now we use the varint routines in the util.c
** file.  Code should use the MACRO forms below, as the Varint32 versions
** are coded to assume the single byte case is already handled (which 
** the MACRO form does).
................................................................................
   0,                         /* isMutexInit */
   0,                         /* isMallocInit */
   0,                         /* isPCacheInit */
   0,                         /* pInitMutex */
   0,                         /* nRefInitMutex */
   0,                         /* xLog */
   0,                         /* pLogArg */

};


/*
** Hash table for global functions - functions common to all
** database connections.  After initialization, this table is
** read-only.
................................................................................
  u32 magic;              /* Magic number for sanity checking */
  char *zErrMsg;          /* Error message written here */
  Vdbe *pPrev,*pNext;     /* Linked list of VDBEs with the same Vdbe.db */
  VdbeCursor **apCsr;     /* One element of this array for each open cursor */
  Mem *aVar;              /* Values for the OP_Variable opcode. */
  char **azVar;           /* Name of variables */
  ynVar nVar;             /* Number of entries in aVar[] */

  u32 cacheCtr;           /* VdbeCursor row cache generation counter */
  int pc;                 /* The program counter */
  int rc;                 /* Value to return */
  u8 errorAction;         /* Recovery action to do in case of an error */
  u8 okVar;               /* True if azVar[] has been initialized */
  u8 explain;             /* True if EXPLAIN present on SQL command */
  u8 changeCntOn;         /* True to update the change-counter */
  u8 expired;             /* True if the VM needs to be recompiled */
  u8 runOnlyOnce;         /* Automatically expire on reset */
  u8 minWriteFileFormat;  /* Minimum file format for writable database files */
  u8 inVtabMethod;        /* See comments above */
  u8 usesStmtJournal;     /* True if uses a statement journal */
................................................................................
**      Willmann-Bell, Inc
**      Richmond, Virginia (USA)
*/
#include <time.h>

#ifndef SQLITE_OMIT_DATETIME_FUNCS

/*
** On recent Windows platforms, the localtime_s() function is available
** as part of the "Secure CRT". It is essentially equivalent to 
** localtime_r() available under most POSIX platforms, except that the 
** order of the parameters is reversed.
**
** See http://msdn.microsoft.com/en-us/library/a442x3ye(VS.80).aspx.
**
** If the user has not indicated to use localtime_r() or localtime_s()
** already, check for an MSVC build environment that provides 
** localtime_s().
*/
#if !defined(HAVE_LOCALTIME_R) && !defined(HAVE_LOCALTIME_S) && \
     defined(_MSC_VER) && defined(_CRT_INSECURE_DEPRECATE)
#define HAVE_LOCALTIME_S 1
#endif

/*
** A structure for holding a single date and time.
*/
typedef struct DateTime DateTime;
struct DateTime {
  sqlite3_int64 iJD; /* The julian day number times 86400000 */
................................................................................
** Clear the YMD and HMS and the TZ
*/
static void clearYMD_HMS_TZ(DateTime *p){
  p->validYMD = 0;
  p->validHMS = 0;
  p->validTZ = 0;
}


















#ifndef SQLITE_OMIT_LOCALTIME
/*







































** Compute the difference (in milliseconds)
** between localtime and UTC (a.k.a. GMT)
** for the time value p where p is in UTC.




*/
static sqlite3_int64 localtimeOffset(DateTime *p){




  DateTime x, y;
  time_t t;





  x = *p;
  computeYMD_HMS(&x);
  if( x.Y<1971 || x.Y>=2038 ){
    x.Y = 2000;
    x.M = 1;
    x.D = 1;
    x.h = 0;
................................................................................
    int s = (int)(x.s + 0.5);
    x.s = s;
  }
  x.tz = 0;
  x.validJD = 0;
  computeJD(&x);
  t = (time_t)(x.iJD/1000 - 21086676*(i64)10000);
#ifdef HAVE_LOCALTIME_R
  {
    struct tm sLocal;
    localtime_r(&t, &sLocal);
    y.Y = sLocal.tm_year + 1900;
    y.M = sLocal.tm_mon + 1;
    y.D = sLocal.tm_mday;
    y.h = sLocal.tm_hour;
    y.m = sLocal.tm_min;
    y.s = sLocal.tm_sec;



  }
#elif defined(HAVE_LOCALTIME_S) && HAVE_LOCALTIME_S
  {
    struct tm sLocal;
    localtime_s(&sLocal, &t);
    y.Y = sLocal.tm_year + 1900;
    y.M = sLocal.tm_mon + 1;
    y.D = sLocal.tm_mday;
    y.h = sLocal.tm_hour;
    y.m = sLocal.tm_min;
    y.s = sLocal.tm_sec;
  }
#else
  {
    struct tm *pTm;
    sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
    pTm = localtime(&t);
    y.Y = pTm->tm_year + 1900;
    y.M = pTm->tm_mon + 1;
    y.D = pTm->tm_mday;
    y.h = pTm->tm_hour;
    y.m = pTm->tm_min;
    y.s = pTm->tm_sec;
    sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER));
  }
#endif
  y.validYMD = 1;
  y.validHMS = 1;
  y.validJD = 0;
  y.validTZ = 0;
  computeJD(&y);

  return y.iJD - x.iJD;
}
#endif /* SQLITE_OMIT_LOCALTIME */

/*
** Process a modifier to a date-time stamp.  The modifiers are
** as follows:
................................................................................
**     start of week
**     start of day
**     weekday N
**     unixepoch
**     localtime
**     utc
**
** Return 0 on success and 1 if there is any kind of error.



*/
static int parseModifier(const char *zMod, DateTime *p){
  int rc = 1;
  int n;
  double r;
  char *z, zBuf[30];
  z = zBuf;
  for(n=0; n<ArraySize(zBuf)-1 && zMod[n]; n++){
    z[n] = (char)sqlite3UpperToLower[(u8)zMod[n]];
................................................................................
      /*    localtime
      **
      ** Assuming the current time value is UTC (a.k.a. GMT), shift it to
      ** show local time.
      */
      if( strcmp(z, "localtime")==0 ){
        computeJD(p);
        p->iJD += localtimeOffset(p);
        clearYMD_HMS_TZ(p);
        rc = 0;
      }
      break;
    }
#endif
    case 'u': {
      /*
      **    unixepoch
................................................................................
        clearYMD_HMS_TZ(p);
        rc = 0;
      }
#ifndef SQLITE_OMIT_LOCALTIME
      else if( strcmp(z, "utc")==0 ){
        sqlite3_int64 c1;
        computeJD(p);
        c1 = localtimeOffset(p);

        p->iJD -= c1;
        clearYMD_HMS_TZ(p);
        p->iJD += c1 - localtimeOffset(p);
        rc = 0;

      }
#endif
      break;
    }
    case 'w': {
      /*
      **    weekday N
................................................................................
  }else{
    z = sqlite3_value_text(argv[0]);
    if( !z || parseDateOrTime(context, (char*)z, p) ){
      return 1;
    }
  }
  for(i=1; i<argc; i++){
    if( (z = sqlite3_value_text(argv[i]))==0 || parseModifier((char*)z, p) ){
      return 1;
    }
  }
  return 0;
}


/*
** The following routines implement the various date and time functions
................................................................................
    while( zIn!=zTerm && (*zIn & 0xc0)==0x80 ){            \
      c = (c<<6) + (0x3f & *(zIn++));                      \
    }                                                      \
    if( c<0x80                                             \
        || (c&0xFFFFF800)==0xD800                          \
        || (c&0xFFFFFFFE)==0xFFFE ){  c = 0xFFFD; }        \
  }
SQLITE_PRIVATE int sqlite3Utf8Read(
  const unsigned char *zIn,       /* First byte of UTF-8 character */
  const unsigned char **pzNext    /* Write first byte past UTF-8 char here */
){
  unsigned int c;

  /* Same as READ_UTF8() above but without the zTerm parameter.
  ** For this routine, we assume the UTF8 string is always zero-terminated.
................................................................................
# endif
#endif /* SQLITE_ENABLE_LOCKING_STYLE */

#if defined(__APPLE__) || (SQLITE_ENABLE_LOCKING_STYLE && !OS_VXWORKS)
# include <sys/mount.h>
#endif





/*
** Allowed values of unixFile.fsFlags
*/
#define SQLITE_FSFLAGS_IS_MSDOS     0x1

/*
** If we are to be thread-safe, include the pthreads header and define
................................................................................


  /* If we have any lock, then the lock file already exists.  All we have
  ** to do is adjust our internal record of the lock level.
  */
  if( pFile->eFileLock > NO_LOCK ){
    pFile->eFileLock = eFileLock;
#if !OS_VXWORKS
    /* Always update the timestamp on the old file */



    utimes(zLockFile, NULL);
#endif
    return SQLITE_OK;
  }
  
  /* grab an exclusive lock */
  fd = robust_open(zLockFile,O_RDONLY|O_CREAT|O_EXCL,0600);
................................................................................
*/
struct unixShmNode {
  unixInodeInfo *pInode;     /* unixInodeInfo that owns this SHM node */
  sqlite3_mutex *mutex;      /* Mutex to access this object */
  char *zFilename;           /* Name of the mmapped file */
  int h;                     /* Open file descriptor */
  int szRegion;              /* Size of shared-memory regions */
  int nRegion;               /* Size of array apRegion */

  char **apRegion;           /* Array of mapped shared-memory regions */
  int nRef;                  /* Number of unixShm objects pointing to this */
  unixShm *pFirst;           /* All unixShm objects pointing to this */
#ifdef SQLITE_DEBUG
  u8 exclMask;               /* Mask of exclusive locks held */
  u8 sharedMask;             /* Mask of shared locks held */
  u8 nextShmId;              /* Next available unixShm.id value */
................................................................................
      goto shm_open_err;
    }

    if( pInode->bProcessLock==0 ){
      pShmNode->h = robust_open(zShmFilename, O_RDWR|O_CREAT,
                               (sStat.st_mode & 0777));
      if( pShmNode->h<0 ){








        rc = unixLogError(SQLITE_CANTOPEN_BKPT, "open", zShmFilename);
        goto shm_open_err;

      }
  
      /* Check to see if another process is holding the dead-man switch.
      ** If not, truncate the file to zero length. 
      */
      rc = SQLITE_OK;
      if( unixShmSystemLock(pShmNode, F_WRLCK, UNIX_SHM_DMS, 1)==SQLITE_OK ){
................................................................................
      rc = SQLITE_IOERR_NOMEM;
      goto shmpage_out;
    }
    pShmNode->apRegion = apNew;
    while(pShmNode->nRegion<=iRegion){
      void *pMem;
      if( pShmNode->h>=0 ){
        pMem = mmap(0, szRegion, PROT_READ|PROT_WRITE, 

            MAP_SHARED, pShmNode->h, pShmNode->nRegion*szRegion
        );
        if( pMem==MAP_FAILED ){
          rc = unixLogError(SQLITE_IOERR_SHMMAP, "mmap", pShmNode->zFilename);
          goto shmpage_out;
        }
      }else{
................................................................................

shmpage_out:
  if( pShmNode->nRegion>iRegion ){
    *pp = pShmNode->apRegion[iRegion];
  }else{
    *pp = 0;
  }

  sqlite3_mutex_leave(pShmNode->mutex);
  return rc;
}

/*
** Change the lock state for a shared-memory segment.
**
................................................................................
    if( nRem>0 ){
      pFile->lastErrno = GetLastError();
      rc = 1;
    }
  }

  if( rc ){
    if( pFile->lastErrno==ERROR_HANDLE_DISK_FULL ){

      return SQLITE_FULL;
    }
    return winLogError(SQLITE_IOERR_WRITE, "winWrite", pFile->zPath);
  }
  return SQLITE_OK;
}

................................................................................
    );
    pCache->pSynced = pPg;
    if( !pPg ){
      for(pPg=pCache->pDirtyTail; pPg && pPg->nRef; pPg=pPg->pDirtyPrev);
    }
    if( pPg ){
      int rc;







      rc = pCache->xStress(pCache->pStress, pPg);
      if( rc!=SQLITE_OK && rc!=SQLITE_BUSY ){
        return rc;
      }
    }

    pPage = sqlite3GlobalConfig.pcache.xFetch(pCache->pCache, pgno, 2);
................................................................................
  pCache = (PCache1 *)sqlite3_malloc(sz);
  if( pCache ){
    memset(pCache, 0, sz);
    if( separateCache ){
      pGroup = (PGroup*)&pCache[1];
      pGroup->mxPinned = 10;
    }else{
      pGroup = &pcache1_g.grp;
    }
    pCache->pGroup = pGroup;
    pCache->szPage = szPage;
    pCache->bPurgeable = (bPurgeable ? 1 : 0);
    if( bPurgeable ){
      pCache->nMin = 10;
      pcache1EnterMutex(pGroup);
................................................................................
  int nWiData;               /* Size of array apWiData */
  volatile u32 **apWiData;   /* Pointer to wal-index content in memory */
  u32 szPage;                /* Database page size */
  i16 readLock;              /* Which read lock is being held.  -1 for none */
  u8 exclusiveMode;          /* Non-zero if connection is in exclusive mode */
  u8 writeLock;              /* True if in a write transaction */
  u8 ckptLock;               /* True if holding a checkpoint lock */
  u8 readOnly;               /* True if the WAL file is open read-only */
  WalIndexHdr hdr;           /* Wal-index header for current transaction */
  const char *zWalName;      /* Name of WAL file */
  u32 nCkpt;                 /* Checkpoint sequence counter in the wal-header */
#ifdef SQLITE_DEBUG
  u8 lockError;              /* True if a locking error has occurred */
#endif
};
................................................................................
/*
** Candidate values for Wal.exclusiveMode.
*/
#define WAL_NORMAL_MODE     0
#define WAL_EXCLUSIVE_MODE  1     
#define WAL_HEAPMEMORY_MODE 2








/*
** Each page of the wal-index mapping contains a hash-table made up of
** an array of HASHTABLE_NSLOT elements of the following type.
*/
typedef u16 ht_slot;

/*
................................................................................
    if( pWal->exclusiveMode==WAL_HEAPMEMORY_MODE ){
      pWal->apWiData[iPage] = (u32 volatile *)sqlite3MallocZero(WALINDEX_PGSZ);
      if( !pWal->apWiData[iPage] ) rc = SQLITE_NOMEM;
    }else{
      rc = sqlite3OsShmMap(pWal->pDbFd, iPage, WALINDEX_PGSZ, 
          pWal->writeLock, (void volatile **)&pWal->apWiData[iPage]
      );




    }
  }

  *ppPage = pWal->apWiData[iPage];
  assert( iPage==0 || *ppPage || rc!=SQLITE_OK );
  return rc;
}
................................................................................
  pRet->zWalName = zWalName;
  pRet->exclusiveMode = (bNoShm ? WAL_HEAPMEMORY_MODE: WAL_NORMAL_MODE);

  /* Open file handle on the write-ahead log file. */
  flags = (SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|SQLITE_OPEN_WAL);
  rc = sqlite3OsOpen(pVfs, zWalName, pRet->pWalFd, flags, &flags);
  if( rc==SQLITE_OK && flags&SQLITE_OPEN_READONLY ){
    pRet->readOnly = 1;
  }

  if( rc!=SQLITE_OK ){
    walIndexClose(pRet, 0);
    sqlite3OsClose(pRet->pWalFd);
    sqlite3_free(pRet);
  }else{
................................................................................
  */
  badHdr = (page0 ? walIndexTryHdr(pWal, pChanged) : 1);

  /* If the first attempt failed, it might have been due to a race
  ** with a writer.  So get a WRITE lock and try again.
  */
  assert( badHdr==0 || pWal->writeLock==0 );






  if( badHdr && SQLITE_OK==(rc = walLockExclusive(pWal, WAL_WRITE_LOCK, 1)) ){
    pWal->writeLock = 1;
    if( SQLITE_OK==(rc = walIndexPage(pWal, 0, &page0)) ){
      badHdr = walIndexTryHdr(pWal, pChanged);
      if( badHdr ){
        /* If the wal-index header is still malformed even while holding
        ** a WRITE lock, it can only mean that the header is corrupted and
        ** needs to be reconstructed.  So run recovery to do exactly that.
        */
        rc = walIndexRecover(pWal);
        *pChanged = 1;
      }
    }
    pWal->writeLock = 0;
    walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1);

  }

  /* If the header is read successfully, check the version number to make
  ** sure the wal-index was not constructed with some future format that
  ** this version of SQLite cannot understand.
  */
  if( badHdr==0 && pWal->hdr.iVersion!=WALINDEX_MAX_VERSION ){
................................................................................
      assert( thisMark!=READMARK_NOT_USED );
      mxReadMark = thisMark;
      mxI = i;
    }
  }
  /* There was once an "if" here. The extra "{" is to preserve indentation. */
  {

    if( mxReadMark < pWal->hdr.mxFrame || mxI==0 ){

      for(i=1; i<WAL_NREADER; i++){
        rc = walLockExclusive(pWal, WAL_READ_LOCK(i), 1);
        if( rc==SQLITE_OK ){
          mxReadMark = pInfo->aReadMark[i] = pWal->hdr.mxFrame;
          mxI = i;
          walUnlockExclusive(pWal, WAL_READ_LOCK(i), 1);
          break;
        }else if( rc!=SQLITE_BUSY ){
          return rc;
        }
      }
    }
    if( mxI==0 ){
      assert( rc==SQLITE_BUSY );
      return WAL_RETRY;
    }

    rc = walLockShared(pWal, WAL_READ_LOCK(mxI));
    if( rc ){
      return rc==SQLITE_BUSY ? WAL_RETRY : rc;
    }
    /* Now that the read-lock has been obtained, check that neither the
................................................................................
  int rc;                         /* Return code */
  int isChanged = 0;              /* True if a new wal-index header is loaded */
  int eMode2 = eMode;             /* Mode to pass to walCheckpoint() */

  assert( pWal->ckptLock==0 );
  assert( pWal->writeLock==0 );


  WALTRACE(("WAL%p: checkpoint begins\n", pWal));
  rc = walLockExclusive(pWal, WAL_CKPT_LOCK, 1);
  if( rc ){
    /* Usually this is SQLITE_BUSY meaning that another thread or process
    ** is already running a checkpoint, or maybe a recovery.  But it might
    ** also be SQLITE_IOERR. */
    return rc;
................................................................................
** the page, 1 means the second cell, and so forth) return a pointer
** to the cell content.
**
** This routine works only for pages that do not contain overflow cells.
*/
#define findCell(P,I) \
  ((P)->aData + ((P)->maskPage & get2byte(&(P)->aData[(P)->cellOffset+2*(I)])))



/*
** This a more complex version of findCell() that works for
** pages that do contain overflow cells.
*/
static u8 *findOverflowCell(MemPage *pPage, int iCell){
  int i;
................................................................................
  if( pCur->eState==CURSOR_INVALID ){
    *pRes = -1;
    assert( pCur->apPage[pCur->iPage]->nCell==0 );
    return SQLITE_OK;
  }
  assert( pCur->apPage[0]->intKey || pIdxKey );
  for(;;){
    int lwr, upr;
    Pgno chldPg;
    MemPage *pPage = pCur->apPage[pCur->iPage];
    int c;

    /* pPage->nCell must be greater than zero. If this is the root-page
    ** the cursor would have been INVALID above and this for(;;) loop
    ** not run. If this is not the root-page, then the moveToChild() routine
................................................................................
    ** be the right kind (index or table) of b-tree page. Otherwise
    ** a moveToChild() or moveToRoot() call would have detected corruption.  */
    assert( pPage->nCell>0 );
    assert( pPage->intKey==(pIdxKey==0) );
    lwr = 0;
    upr = pPage->nCell-1;
    if( biasRight ){
      pCur->aiIdx[pCur->iPage] = (u16)upr;
    }else{
      pCur->aiIdx[pCur->iPage] = (u16)((upr+lwr)/2);
    }
    for(;;){
      int idx = pCur->aiIdx[pCur->iPage]; /* Index of current cell in pPage */
      u8 *pCell;                          /* Pointer to current cell in pPage */


      pCur->info.nSize = 0;
      pCell = findCell(pPage, idx) + pPage->childPtrSize;
      if( pPage->intKey ){
        i64 nCellKey;
        if( pPage->hasData ){
          u32 dummy;
          pCell += getVarint32(pCell, dummy);
................................................................................
        lwr = idx+1;
      }else{
        upr = idx-1;
      }
      if( lwr>upr ){
        break;
      }
      pCur->aiIdx[pCur->iPage] = (u16)((lwr+upr)/2);
    }
    assert( lwr==upr+1 );
    assert( pPage->isInit );
    if( pPage->leaf ){
      chldPg = 0;
    }else if( lwr>=pPage->nCell ){
      chldPg = get4byte(&pPage->aData[pPage->hdrOffset+8]);
................................................................................
** The cell content is not freed or deallocated.  It is assumed that
** the cell content has been copied someplace else.  This routine just
** removes the reference to the cell from pPage.
**
** "sz" must be the number of bytes in the cell.
*/
static void dropCell(MemPage *pPage, int idx, int sz, int *pRC){
  int i;          /* Loop counter */
  u32 pc;         /* Offset to cell content of cell being deleted */
  u8 *data;       /* pPage->aData */
  u8 *ptr;        /* Used to move bytes around within data[] */

  int rc;         /* The return code */
  int hdr;        /* Beginning of the header.  0 most pages.  100 page 1 */

  if( *pRC ) return;

  assert( idx>=0 && idx<pPage->nCell );
  assert( sz==cellSize(pPage, idx) );
................................................................................
    return;
  }
  rc = freeSpace(pPage, pc, sz);
  if( rc ){
    *pRC = rc;
    return;
  }
  for(i=idx+1; i<pPage->nCell; i++, ptr+=2){
    ptr[0] = ptr[2];
    ptr[1] = ptr[3];


  }
  pPage->nCell--;
  put2byte(&data[hdr+3], pPage->nCell);
  pPage->nFree += 2;
}

/*
................................................................................
  int idx = 0;      /* Where to write new cell content in data[] */
  int j;            /* Loop counter */
  int end;          /* First byte past the last cell pointer in data[] */
  int ins;          /* Index in data[] where new cell pointer is inserted */
  int cellOffset;   /* Address of first cell pointer in data[] */
  u8 *data;         /* The content of the whole page */
  u8 *ptr;          /* Used for moving information around in data[] */


  int nSkip = (iChild ? 4 : 0);

  if( *pRC ) return;

  assert( i>=0 && i<=pPage->nCell+pPage->nOverflow );
  assert( pPage->nCell<=MX_CELL(pPage->pBt) && MX_CELL(pPage->pBt)<=10921 );
................................................................................
    assert( idx+sz <= (int)pPage->pBt->usableSize );
    pPage->nCell++;
    pPage->nFree -= (u16)(2 + sz);
    memcpy(&data[idx+nSkip], pCell+nSkip, sz-nSkip);
    if( iChild ){
      put4byte(&data[idx], iChild);
    }
    for(j=end, ptr=&data[j]; j>ins; j-=2, ptr-=2){
      ptr[0] = ptr[-2];
      ptr[1] = ptr[-1];



    }
    put2byte(&data[ins], idx);
    put2byte(&data[pPage->hdrOffset+3], pPage->nCell);
#ifndef SQLITE_OMIT_AUTOVACUUM
    if( pPage->pBt->autoVacuum ){
      /* The cell may contain a pointer to an overflow page. If so, write
      ** the entry for the overflow page into the pointer map.
................................................................................
  /* Check that the page has just been zeroed by zeroPage() */
  assert( pPage->nCell==0 );
  assert( get2byteNotZero(&data[hdr+5])==nUsable );

  pCellptr = &data[pPage->cellOffset + nCell*2];
  cellbody = nUsable;
  for(i=nCell-1; i>=0; i--){

    pCellptr -= 2;
    cellbody -= aSize[i];
    put2byte(pCellptr, cellbody);
    memcpy(&data[cellbody], apCell[i], aSize[i]);
  }
  put2byte(&data[hdr+3], nCell);
  put2byte(&data[hdr+5], cellbody);
  pPage->nFree -= (nCell*2 + nUsable - cellbody);
  pPage->nCell = (u16)nCell;
}

................................................................................
    ** process of being overwritten.  */
    MemPage *pOld = apCopy[i] = (MemPage*)&aSpace1[pBt->pageSize + k*i];
    memcpy(pOld, apOld[i], sizeof(MemPage));
    pOld->aData = (void*)&pOld[1];
    memcpy(pOld->aData, apOld[i]->aData, pBt->pageSize);

    limit = pOld->nCell+pOld->nOverflow;

    for(j=0; j<limit; j++){
      assert( nCell<nMaxCells );
      apCell[nCell] = findOverflowCell(pOld, j);
      szCell[nCell] = cellSizePtr(pOld, apCell[nCell]);
      nCell++;
    }











    if( i<nOld-1 && !leafData){
      u16 sz = (u16)szNew[i];
      u8 *pTemp;
      assert( nCell<nMaxCells );
      szCell[nCell] = sz;
      pTemp = &aSpace1[iSpace1];
      iSpace1 += sz;
................................................................................
  pOp->opcode = (u8)op;
  pOp->p5 = 0;
  pOp->p1 = p1;
  pOp->p2 = p2;
  pOp->p3 = p3;
  pOp->p4.p = 0;
  pOp->p4type = P4_NOTUSED;
  p->expired = 0;
  if( op==OP_ParseSchema ){
    /* Any program that uses the OP_ParseSchema opcode needs to lock
    ** all btrees. */
    int j;
    for(j=0; j<p->db->nDb; j++) sqlite3VdbeUsesBtree(p, j);
  }
#ifdef SQLITE_DEBUG
  pOp->zComment = 0;
  if( sqlite3VdbeAddopTrace ) sqlite3VdbePrintOp(0, i, &p->aOp[i]);
#endif
#ifdef VDBE_PROFILE
  pOp->cycles = 0;
  pOp->cnt = 0;
................................................................................
  const char *zP4,    /* The P4 operand */
  int p4type          /* P4 operand type */
){
  int addr = sqlite3VdbeAddOp3(p, op, p1, p2, p3);
  sqlite3VdbeChangeP4(p, addr, zP4, p4type);
  return addr;
}















/*
** Add an opcode that includes the p4 value as an integer.
*/
SQLITE_PRIVATE int sqlite3VdbeAddOp4Int(
  Vdbe *p,            /* Add the opcode to this VM */
  int op,             /* The new opcode */
................................................................................
  }else{
    *pnByte += nByte;
  }
  return pBuf;
}

/*








































** Prepare a virtual machine for execution.  This involves things such

** as allocating stack space and initializing the program counter.
** After the VDBE has be prepped, it can be executed by one or more
** calls to sqlite3VdbeExec().  
**
** This is the only way to move a VDBE from VDBE_MAGIC_INIT to
** VDBE_MAGIC_RUN.







**
** This function may be called more than once on a single virtual machine.
** The first call is made while compiling the SQL statement. Subsequent
** calls are made as part of the process of resetting a statement to be
** re-executed (from a call to sqlite3_reset()). The nVar, nMem, nCursor 
** and isExplain parameters are only passed correct values the first time
** the function is called. On subsequent calls, from sqlite3_reset(), nVar
** is passed -1 and nMem, nCursor and isExplain are all passed zero.


*/
SQLITE_PRIVATE void sqlite3VdbeMakeReady(
  Vdbe *p,                       /* The VDBE */
  int nVar,                      /* Number of '?' see in the SQL statement */
  int nMem,                      /* Number of memory cells to allocate */
  int nCursor,                   /* Number of cursors to allocate */
  int nArg,                      /* Maximum number of args in SubPrograms */
  int isExplain,                 /* True if the EXPLAIN keywords is present */
  int usesStmtJournal            /* True to set Vdbe.usesStmtJournal */

){
  int n;
  sqlite3 *db = p->db;










  assert( p!=0 );


  assert( p->magic==VDBE_MAGIC_INIT );







  /* There should be at least one opcode.
  */
  assert( p->nOp>0 );

  /* Set the magic to VDBE_MAGIC_RUN sooner rather than later. */
  p->magic = VDBE_MAGIC_RUN;

  /* For each cursor required, also allocate a memory cell. Memory
  ** cells (nMem+1-nCursor)..nMem, inclusive, will never be used by
  ** the vdbe program. Instead they are used to allocate space for
  ** VdbeCursor/BtCursor structures. The blob of memory associated with 
  ** cursor 0 is stored in memory cell nMem. Memory cell (nMem-1)
  ** stores the blob of memory associated with cursor 1, etc.
  **
  ** See also: allocateCursor().
  */
  nMem += nCursor;

  /* Allocate space for memory registers, SQL variables, VDBE cursors and 
  ** an array to marshal SQL function arguments in. This is only done the
  ** first time this function is called for a given VDBE, not when it is
  ** being called from sqlite3_reset() to reset the virtual machine.
  */
  if( nVar>=0 && ALWAYS(db->mallocFailed==0) ){
    u8 *zCsr = (u8 *)&p->aOp[p->nOp];       /* Memory avaliable for alloation */
    u8 *zEnd = (u8 *)&p->aOp[p->nOpAlloc];  /* First byte past available mem */
    int nByte;                              /* How much extra memory needed */

    resolveP2Values(p, &nArg);
    p->usesStmtJournal = (u8)usesStmtJournal;
    if( isExplain && nMem<10 ){
      nMem = 10;
    }
    memset(zCsr, 0, zEnd-zCsr);
    zCsr += (zCsr - (u8*)0)&7;
    assert( EIGHT_BYTE_ALIGNMENT(zCsr) );

    /* Memory for registers, parameters, cursor, etc, is allocated in two
    ** passes.  On the first pass, we try to reuse unused space at the 
    ** end of the opcode array.  If we are unable to satisfy all memory
    ** requirements by reusing the opcode array tail, then the second
    ** pass will fill in the rest using a fresh allocation.  
    **
    ** This two-pass approach that reuses as much memory as possible from
    ** the leftover space at the end of the opcode array can significantly
    ** reduce the amount of memory held by a prepared statement.
    */
    do {
      nByte = 0;
      p->aMem = allocSpace(p->aMem, nMem*sizeof(Mem), &zCsr, zEnd, &nByte);
      p->aVar = allocSpace(p->aVar, nVar*sizeof(Mem), &zCsr, zEnd, &nByte);
      p->apArg = allocSpace(p->apArg, nArg*sizeof(Mem*), &zCsr, zEnd, &nByte);
      p->azVar = allocSpace(p->azVar, nVar*sizeof(char*), &zCsr, zEnd, &nByte);
      p->apCsr = allocSpace(p->apCsr, nCursor*sizeof(VdbeCursor*),
                            &zCsr, zEnd, &nByte);
      if( nByte ){
        p->pFree = sqlite3DbMallocZero(db, nByte);
      }
      zCsr = p->pFree;
      zEnd = &zCsr[nByte];
    }while( nByte && !db->mallocFailed );

    p->nCursor = (u16)nCursor;
    if( p->aVar ){
      p->nVar = (ynVar)nVar;
      for(n=0; n<nVar; n++){
        p->aVar[n].flags = MEM_Null;
        p->aVar[n].db = db;
      }
    }





    if( p->aMem ){
      p->aMem--;                      /* aMem[] goes from 1..nMem */
      p->nMem = nMem;                 /*       not from 0..nMem-1 */
      for(n=1; n<=nMem; n++){
        p->aMem[n].flags = MEM_Null;
        p->aMem[n].db = db;
      }
    }
  }
#ifdef SQLITE_DEBUG
  for(n=1; n<p->nMem; n++){
    assert( p->aMem[n].db==db );
  }
#endif

  p->pc = -1;
  p->rc = SQLITE_OK;
  p->errorAction = OE_Abort;
  p->explain |= isExplain;
  p->magic = VDBE_MAGIC_RUN;
  p->nChange = 0;
  p->cacheCtr = 1;
  p->minWriteFileFormat = 255;
  p->iStatement = 0;
  p->nFkConstraint = 0;
#ifdef VDBE_PROFILE
  {
    int i;
    for(i=0; i<p->nOp; i++){
      p->aOp[i].cnt = 0;
      p->aOp[i].cycles = 0;
    }
  }
#endif

}

/*
** Close a VDBE cursor and release all the resources that cursor 
** happens to hold.
*/
SQLITE_PRIVATE void sqlite3VdbeFreeCursor(Vdbe *p, VdbeCursor *pCx){
................................................................................
** Free all memory associated with the Vdbe passed as the second argument.
** The difference between this function and sqlite3VdbeDelete() is that
** VdbeDelete() also unlinks the Vdbe from the list of VMs associated with
** the database connection.
*/
SQLITE_PRIVATE void sqlite3VdbeDeleteObject(sqlite3 *db, Vdbe *p){
  SubProgram *pSub, *pNext;

  assert( p->db==0 || p->db==db );
  releaseMemArray(p->aVar, p->nVar);
  releaseMemArray(p->aColName, p->nResColumn*COLNAME_N);
  for(pSub=p->pProgram; pSub; pSub=pNext){
    pNext = pSub->pNext;
    vdbeFreeOpArray(db, pSub->aOp, pSub->nOp);
    sqlite3DbFree(db, pSub);
  }

  vdbeFreeOpArray(db, p->aOp, p->nOp);
  sqlite3DbFree(db, p->aLabel);
  sqlite3DbFree(db, p->aColName);
  sqlite3DbFree(db, p->zSql);
  sqlite3DbFree(db, p->pFree);
  sqlite3DbFree(db, p);
}
................................................................................
  u = 0;
  while( idx<szHdr && u<p->nField && d<=nKey ){
    u32 serial_type;

    idx += getVarint32(&aKey[idx], serial_type);
    pMem->enc = pKeyInfo->enc;
    pMem->db = pKeyInfo->db;
    pMem->flags = 0;
    pMem->zMalloc = 0;
    d += sqlite3VdbeSerialGet(&aKey[d], serial_type, pMem);
    pMem++;
    u++;
  }
  assert( u<=pKeyInfo->nField + 1 );
  p->nField = u;
................................................................................
  return (void*)p;
}

/*
** This routine destroys a UnpackedRecord object.
*/
SQLITE_PRIVATE void sqlite3VdbeDeleteUnpackedRecord(UnpackedRecord *p){

  int i;
  Mem *pMem;

  assert( p!=0 );
  assert( p->flags & UNPACKED_NEED_DESTROY );
  for(i=0, pMem=p->aMem; i<p->nField; i++, pMem++){
    /* The unpacked record is always constructed by the
    ** sqlite3VdbeUnpackRecord() function above, which makes all
    ** strings and blobs static.  And none of the elements are
    ** ever transformed, so there is never anything to delete.
    */
    if( NEVER(pMem->zMalloc) ) sqlite3VdbeMemRelease(pMem);
  }

  if( p->flags & UNPACKED_NEED_FREE ){
    sqlite3DbFree(p->pKeyInfo->db, p);
  }
}

/*
** This function compares the two table rows or index records
................................................................................
  int rc;
  if( pStmt==0 ){
    rc = SQLITE_OK;
  }else{
    Vdbe *v = (Vdbe*)pStmt;
    sqlite3_mutex_enter(v->db->mutex);
    rc = sqlite3VdbeReset(v);
    sqlite3VdbeMakeReady(v, -1, 0, 0, 0, 0, 0);
    assert( (rc & (v->db->errMask))==rc );
    rc = sqlite3ApiExit(v->db, rc);
    sqlite3_mutex_leave(v->db->mutex);
  }
  return rc;
}

................................................................................
    ** caller. Set the error code in the database handle to the same value.
    */ 
    rc = db->errCode = p->rc;
  }
  return (rc&db->errMask);
}









/*
** This is the top-level implementation of sqlite3_step().  Call
** sqlite3Step() to do most of the work.  If a schema error occurs,
** call sqlite3Reprepare() and try again.
*/
SQLITE_API int sqlite3_step(sqlite3_stmt *pStmt){
  int rc = SQLITE_OK;      /* Result from sqlite3Step() */
................................................................................

  if( vdbeSafetyNotNull(v) ){
    return SQLITE_MISUSE_BKPT;
  }
  db = v->db;
  sqlite3_mutex_enter(db->mutex);
  while( (rc = sqlite3Step(v))==SQLITE_SCHEMA
         && cnt++ < 5
         && (rc2 = rc = sqlite3Reprepare(v))==SQLITE_OK ){
    sqlite3_reset(pStmt);
    v->expired = 0;
  }
  if( rc2!=SQLITE_OK && ALWAYS(v->isPrepareV2) && ALWAYS(db->pErr) ){
    /* This case occurs after failing to recompile an sql statement. 
    ** The error message from the SQL compiler has already been loaded 
................................................................................
** This routine is added to support DBD::SQLite.  
*/
SQLITE_API int sqlite3_bind_parameter_count(sqlite3_stmt *pStmt){
  Vdbe *p = (Vdbe*)pStmt;
  return p ? p->nVar : 0;
}

/*
** Create a mapping from variable numbers to variable names
** in the Vdbe.azVar[] array, if such a mapping does not already
** exist.
*/
static void createVarMap(Vdbe *p){
  if( !p->okVar ){
    int j;
    Op *pOp;
    sqlite3_mutex_enter(p->db->mutex);
    /* The race condition here is harmless.  If two threads call this
    ** routine on the same Vdbe at the same time, they both might end
    ** up initializing the Vdbe.azVar[] array.  That is a little extra
    ** work but it results in the same answer.
    */
    for(j=0, pOp=p->aOp; j<p->nOp; j++, pOp++){
      if( pOp->opcode==OP_Variable ){
        assert( pOp->p1>0 && pOp->p1<=p->nVar );
        p->azVar[pOp->p1-1] = pOp->p4.z;
      }
    }
    p->okVar = 1;
    sqlite3_mutex_leave(p->db->mutex);
  }
}

/*
** Return the name of a wildcard parameter.  Return NULL if the index
** is out of range or if the wildcard is unnamed.
**
** The result is always UTF-8.
*/
SQLITE_API const char *sqlite3_bind_parameter_name(sqlite3_stmt *pStmt, int i){
  Vdbe *p = (Vdbe*)pStmt;
  if( p==0 || i<1 || i>p->nVar ){
    return 0;
  }
  createVarMap(p);
  return p->azVar[i-1];
}

/*
** Given a wildcard parameter name, return the index of the variable
** with that name.  If there is no variable with the given name,
** return 0.
*/
SQLITE_PRIVATE int sqlite3VdbeParameterIndex(Vdbe *p, const char *zName, int nName){
  int i;
  if( p==0 ){
    return 0;
  }
  createVarMap(p); 
  if( zName ){
    for(i=0; i<p->nVar; i++){
      const char *z = p->azVar[i];
      if( z && memcmp(z,zName,nName)==0 && z[nName]==0 ){
        return i+1;
      }
    }
  }
  return 0;
................................................................................
      int i;
      sqlite_int64 rowid;
      Mem **apArg;
      Mem *pX;
    } cm;
    struct OP_Trace_stack_vars {
      char *zTrace;

    } cn;
  } u;
  /* End automatically generated code
  ********************************************************************/

  assert( p->magic==VDBE_MAGIC_RUN );  /* sqlite3_step() verifies this */
  sqlite3VdbeEnter(p);
................................................................................
  REGISTER_TRACE(pOp->p1, pIn1);
  pc = u.aa.pcDest;
  break;
}

/* Opcode:  HaltIfNull  P1 P2 P3 P4 *
**
** Check the value in register P3.  If is is NULL then Halt using
** parameter P1, P2, and P4 as if this were a Halt instruction.  If the
** value in register P3 is not NULL, then this routine is a no-op.
*/
case OP_HaltIfNull: {      /* in3 */
  pIn3 = &aMem[pOp->p3];
  if( (pIn3->flags & MEM_Null)==0 ) break;
  /* Fall through into OP_Halt */
................................................................................
*/
case OP_Variable: {            /* out2-prerelease */
#if 0  /* local variables moved into u.ab */
  Mem *pVar;       /* Value being transferred */
#endif /* local variables moved into u.ab */

  assert( pOp->p1>0 && pOp->p1<=p->nVar );

  u.ab.pVar = &p->aVar[pOp->p1 - 1];
  if( sqlite3VdbeMemTooBig(u.ab.pVar) ){
    goto too_big;
  }
  sqlite3VdbeMemShallowCopy(pOut, u.ab.pVar, MEM_Static);
  UPDATE_MAX_BLOBSIZE(pOut);
  break;
................................................................................
    assert( pOp[-1].p4type==P4_COLLSEQ );
    assert( pOp[-1].opcode==OP_CollSeq );
    u.ag.ctx.pColl = pOp[-1].p4.pColl;
  }
  db->lastRowid = lastRowid;
  (*u.ag.ctx.pFunc->xFunc)(&u.ag.ctx, u.ag.n, u.ag.apVal); /* IMP: R-24505-23230 */
  lastRowid = db->lastRowid;










  if( db->mallocFailed ){
    /* Even though a malloc() has failed, the implementation of the
    ** user function may have called an sqlite3_result_XXX() function
    ** to return a value. The following call releases any resources
    ** associated with such a value.
    */
    sqlite3VdbeMemRelease(&u.ag.ctx.s);
    goto no_mem;
  }

  /* If any auxiliary data functions have been called by this user function,
  ** immediately call the destructor for any non-static values.
  */
  if( u.ag.ctx.pVdbeFunc ){
    sqlite3VdbeDeleteAuxData(u.ag.ctx.pVdbeFunc, pOp->p1);
    pOp->p4.pVdbeFunc = u.ag.ctx.pVdbeFunc;
    pOp->p4type = P4_VDBEFUNC;
  }

  /* If the function returned an error, throw an exception */
  if( u.ag.ctx.isError ){
    sqlite3SetString(&p->zErrMsg, db, "%s", sqlite3_value_text(&u.ag.ctx.s));
    rc = u.ag.ctx.isError;
  }

  /* Copy the result of the function into register P3 */
................................................................................
** This works just like the Lt opcode except that the jump is taken if
** the operands in registers P1 and P3 are not equal.  See the Lt opcode for
** additional information.
**
** If SQLITE_NULLEQ is set in P5 then the result of comparison is always either
** true or false and is never NULL.  If both operands are NULL then the result
** of comparison is false.  If either operand is NULL then the result is true.
** If neither operand is NULL the the result is the same as it would be if
** the SQLITE_NULLEQ flag were omitted from P5.
*/
/* Opcode: Eq P1 P2 P3 P4 P5
**
** This works just like the Lt opcode except that the jump is taken if
** the operands in registers P1 and P3 are equal.
** See the Lt opcode for additional information.
**
** If SQLITE_NULLEQ is set in P5 then the result of comparison is always either
** true or false and is never NULL.  If both operands are NULL then the result
** of comparison is true.  If either operand is NULL then the result is false.
** If neither operand is NULL the the result is the same as it would be if
** the SQLITE_NULLEQ flag were omitted from P5.
*/
/* Opcode: Le P1 P2 P3 P4 P5
**
** This works just like the Lt opcode except that the jump is taken if
** the content of register P3 is less than or equal to the content of
** register P1.  See the Lt opcode for additional information.
................................................................................
  u16 flags3;         /* Copy of initial value of pIn3->flags */
#endif /* local variables moved into u.ai */

  pIn1 = &aMem[pOp->p1];
  pIn3 = &aMem[pOp->p3];
  u.ai.flags1 = pIn1->flags;
  u.ai.flags3 = pIn3->flags;
  if( (pIn1->flags | pIn3->flags)&MEM_Null ){
    /* One or both operands are NULL */
    if( pOp->p5 & SQLITE_NULLEQ ){
      /* If SQLITE_NULLEQ is set (which will only happen if the operator is
      ** OP_Eq or OP_Ne) then take the jump or not depending on whether
      ** or not both operands are null.
      */
      assert( pOp->opcode==OP_Eq || pOp->opcode==OP_Ne );
      u.ai.res = (pIn1->flags & pIn3->flags & MEM_Null)==0;
    }else{
      /* SQLITE_NULLEQ is clear and at least one operand is NULL,
      ** then the result is always NULL.
      ** The jump is taken if the SQLITE_JUMPIFNULL bit is set.
      */
      if( pOp->p5 & SQLITE_STOREP2 ){
        pOut = &aMem[pOp->p2];
................................................................................
    sqlite3VdbeMemSetInt64(pOut, ~sqlite3VdbeIntValue(pIn1));
  }
  break;
}

/* Opcode: If P1 P2 P3 * *
**
** Jump to P2 if the value in register P1 is true.  The value is
** is considered true if it is numeric and non-zero.  If the value
** in P1 is NULL then take the jump if P3 is true.
*/
/* Opcode: IfNot P1 P2 P3 * *
**
** Jump to P2 if the value in register P1 is False.  The value is
** is considered true if it has a numeric value of zero.  If the value
** in P1 is NULL then take the jump if P3 is true.
*/
case OP_If:                 /* jump, in1 */
case OP_IfNot: {            /* jump, in1 */
#if 0  /* local variables moved into u.al */
  int c;
................................................................................
      */
      sqlite3SetString(&p->zErrMsg, db, "cannot open savepoint - "
        "SQL statements in progress");
      rc = SQLITE_BUSY;
    }else{
      u.aq.nName = sqlite3Strlen30(u.aq.zName);


      /* This call is Ok even if this savepoint is actually a transaction
      ** savepoint (and therefore should not prompt xSavepoint()) callbacks.
      ** If this is a transaction savepoint being opened, it is guaranteed
      ** that the db->aVTrans[] array is empty.  */
      assert( db->autoCommit==0 || db->nVTrans==0 );
      rc = sqlite3VtabSavepoint(db, SAVEPOINT_BEGIN,
                                db->nStatement+db->nSavepoint);
      if( rc!=SQLITE_OK ) goto abort_due_to_error;


      /* Create a new savepoint structure. */
      u.aq.pNew = sqlite3DbMallocRaw(db, sizeof(Savepoint)+u.aq.nName+1);
      if( u.aq.pNew ){
        u.aq.pNew->zName = (char *)&u.aq.pNew[1];
        memcpy(u.aq.pNew->zName, u.aq.zName, u.aq.nName+1);

................................................................................
    }
  }
  break;
}

/* Opcode: NotExists P1 P2 P3 * *
**
** Use the content of register P3 as a integer key.  If a record 
** with that key does not exist in table of P1, then jump to P2. 
** If the record does exist, then fall through.  The cursor is left 
** pointing to the record if it exists.
**
** The difference between this operation and NotFound is that this
** operation assumes the key is an integer and that P1 is a table whereas
** NotFound assumes key is a blob constructed from MakeRecord and
................................................................................
** The record number is not previously used as a key in the database
** table that cursor P1 points to.  The new record number is written
** written to register P2.
**
** If P3>0 then P3 is a register in the root frame of this VDBE that holds 
** the largest previously generated record number. No new record numbers are
** allowed to be less than this value. When this value reaches its maximum, 
** a SQLITE_FULL error is generated. The P3 register is updated with the '
** generated record number. This P3 mechanism is used to help implement the
** AUTOINCREMENT feature.
*/
case OP_NewRowid: {           /* out2-prerelease */
#if 0  /* local variables moved into u.be */
  i64 v;                 /* The new rowid */
  VdbeCursor *pC;        /* Cursor of table to get the new rowid */
................................................................................
  }
  u.bm.pC->rowidIsValid = 0;
  break;
}

/* Opcode: IdxInsert P1 P2 P3 * P5
**
** Register P2 holds a SQL index key made using the
** MakeRecord instructions.  This opcode writes that key
** into the index P1.  Data for the entry is nil.
**
** P3 is a flag that provides a hint to the b-tree layer that this
** insert is likely to be an append.
**
** This instruction only works for indices.  The equivalent instruction
................................................................................
**
** If tracing is enabled (by the sqlite3_trace()) interface, then
** the UTF-8 string contained in P4 is emitted on the trace callback.
*/
case OP_Trace: {
#if 0  /* local variables moved into u.cn */
  char *zTrace;

#endif /* local variables moved into u.cn */

  u.cn.zTrace = (pOp->p4.z ? pOp->p4.z : p->zSql);
  if( u.cn.zTrace ){
    if( db->xTrace ){
      char *z = sqlite3VdbeExpandSql(p, u.cn.zTrace);
      db->xTrace(db->pTraceArg, z);
      sqlite3DbFree(db, z);
    }
#ifdef SQLITE_DEBUG
    if( (db->flags & SQLITE_SqlTrace)!=0 ){


      sqlite3DebugPrintf("SQL-trace: %s\n", u.cn.zTrace);
    }
#endif /* SQLITE_DEBUG */
  }
  break;
}
#endif


/* Opcode: Noop * * * * *
**
................................................................................
      ** always return an SQL NULL. This is useful because it means
      ** we can invoke OP_Column to fill in the vdbe cursors type 
      ** and offset cache without causing any IO.
      */
      sqlite3VdbeChangeP4(v, 3+flags, SQLITE_INT_TO_PTR(pTab->nCol+1),P4_INT32);
      sqlite3VdbeChangeP2(v, 7, pTab->nCol);
      if( !db->mallocFailed ){



        sqlite3VdbeMakeReady(v, 1, 1, 1, 0, 0, 0);
      }
    }
   
    pBlob->flags = flags;
    pBlob->iCol = iCol;
    pBlob->db = db;
    sqlite3BtreeLeaveAll(db);
................................................................................
  z = pExpr->u.zToken;
  assert( z!=0 );
  assert( z[0]!=0 );
  if( z[1]==0 ){
    /* Wildcard of the form "?".  Assign the next variable number */
    assert( z[0]=='?' );
    pExpr->iColumn = (ynVar)(++pParse->nVar);



  }else if( z[0]=='?' ){
    /* Wildcard of the form "?nnn".  Convert "nnn" to an integer and
    ** use it as the variable number */
    i64 i;
    int bOk = 0==sqlite3Atoi64(&z[1], &i, sqlite3Strlen30(&z[1]), SQLITE_UTF8);
    pExpr->iColumn = (ynVar)i;
    testcase( i==0 );
    testcase( i==1 );
    testcase( i==db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER]-1 );
    testcase( i==db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER] );
    if( bOk==0 || i<1 || i>db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER] ){
      sqlite3ErrorMsg(pParse, "variable number must be between ?1 and ?%d",
          db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER]);

    }
    if( i>pParse->nVar ){
      pParse->nVar = (int)i;
    }
  }else{
    /* Wildcards like ":aaa", "$aaa" or "@aaa".  Reuse the same variable
    ** number as the prior appearance of the same name, or if the name
    ** has never appeared before, reuse the same variable number
    */
    int i;
    u32 n;
    n = sqlite3Strlen30(z);
    for(i=0; i<pParse->nVarExpr; i++){
      Expr *pE = pParse->apVarExpr[i];
      assert( pE!=0 );
      if( memcmp(pE->u.zToken, z, n)==0 && pE->u.zToken[n]==0 ){
        pExpr->iColumn = pE->iColumn;
        break;
      }
    }
    if( i>=pParse->nVarExpr ){
      pExpr->iColumn = (ynVar)(++pParse->nVar);

      if( pParse->nVarExpr>=pParse->nVarExprAlloc-1 ){
        pParse->nVarExprAlloc += pParse->nVarExprAlloc + 10;
        pParse->apVarExpr =

            sqlite3DbReallocOrFree(
              db,
              pParse->apVarExpr,
              pParse->nVarExprAlloc*sizeof(pParse->apVarExpr[0])
            );

      }
      if( !db->mallocFailed ){
        assert( pParse->apVarExpr!=0 );
        pParse->apVarExpr[pParse->nVarExpr++] = pExpr;
      }
    }
  } 
  if( !pParse->nErr && pParse->nVar>db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER] ){
    sqlite3ErrorMsg(pParse, "too many SQL variables");
  }
}
................................................................................
#endif
    case TK_VARIABLE: {
      assert( !ExprHasProperty(pExpr, EP_IntValue) );
      assert( pExpr->u.zToken!=0 );
      assert( pExpr->u.zToken[0]!=0 );
      sqlite3VdbeAddOp2(v, OP_Variable, pExpr->iColumn, target);
      if( pExpr->u.zToken[1]!=0 ){


        sqlite3VdbeChangeP4(v, -1, pExpr->u.zToken, P4_TRANSIENT);
      }
      break;
    }
    case TK_REGISTER: {
      inReg = pExpr->iTable;
      break;
    }
................................................................................

  /* Drop the table and index from the internal schema.  */
  sqlite3VdbeAddOp4(v, OP_DropTable, iDb, 0, 0, pTab->zName, 0);

  /* Reload the table, index and permanent trigger schemas. */
  zWhere = sqlite3MPrintf(pParse->db, "tbl_name=%Q", zName);
  if( !zWhere ) return;
  sqlite3VdbeAddOp4(v, OP_ParseSchema, iDb, 0, 0, zWhere, P4_DYNAMIC);

#ifndef SQLITE_OMIT_TRIGGER
  /* Now, if the table is not stored in the temp database, reload any temp 
  ** triggers. Don't use IN(...) in case SQLITE_OMIT_SUBQUERY is defined. 
  */
  if( (zWhere=whereTempTriggers(pParse, pTab))!=0 ){
    sqlite3VdbeAddOp4(v, OP_ParseSchema, 1, 0, 0, zWhere, P4_DYNAMIC);
  }
#endif
}

/*
** Parameter zName is the name of a table that is about to be altered
** (either with ALTER TABLE ... RENAME TO or ALTER TABLE ... ADD COLUMN).
................................................................................
    FILE *trace = (db->flags & SQLITE_VdbeTrace)!=0 ? stdout : 0;
    sqlite3VdbeTrace(v, trace);
#endif
    assert( pParse->iCacheLevel==0 );  /* Disables and re-enables match */
    /* A minimum of one cursor is required if autoincrement is used
    *  See ticket [a696379c1f08866] */
    if( pParse->pAinc!=0 && pParse->nTab==0 ) pParse->nTab = 1;
    sqlite3VdbeMakeReady(v, pParse->nVar, pParse->nMem,
                         pParse->nTab, pParse->nMaxArg, pParse->explain,
                         pParse->isMultiWrite && pParse->mayAbort);
    pParse->rc = SQLITE_DONE;
    pParse->colNamesSet = 0;
  }else{
    pParse->rc = SQLITE_ERROR;
  }
  pParse->nTab = 0;
  pParse->nMem = 0;
................................................................................
          pDb->zName
        );
      }
    }
#endif

    /* Reparse everything to update our internal data structures */
    sqlite3VdbeAddOp4(v, OP_ParseSchema, iDb, 0, 0,
        sqlite3MPrintf(db, "tbl_name='%q'",p->zName), P4_DYNAMIC);
  }


  /* Add the table to the in-memory representation of the database.
  */
  if( db->init.busy ){
    Table *pOld;
................................................................................

    /* Fill the index with data and reparse the schema. Code an OP_Expire
    ** to invalidate all pre-compiled statements.
    */
    if( pTblName ){
      sqlite3RefillIndex(pParse, pIndex, iMem);
      sqlite3ChangeCookie(pParse, iDb);
      sqlite3VdbeAddOp4(v, OP_ParseSchema, iDb, 0, 0,
         sqlite3MPrintf(db, "name='%q' AND type='index'", pIndex->zName), 
         P4_DYNAMIC);
      sqlite3VdbeAddOp1(v, OP_Expire, 0);
    }
  }

  /* When adding an index to the list of indices for a table, make
  ** sure all indices labeled OE_Replace come after all those labeled
  ** OE_Ignore.  This is necessary for the correct constraint check
................................................................................

    /* Delete the row */
#ifndef SQLITE_OMIT_VIRTUALTABLE
    if( IsVirtual(pTab) ){
      const char *pVTab = (const char *)sqlite3GetVTable(db, pTab);
      sqlite3VtabMakeWritable(pParse, pTab);
      sqlite3VdbeAddOp4(v, OP_VUpdate, 0, 1, iRowid, pVTab, P4_VTAB);

      sqlite3MayAbort(pParse);
    }else
#endif
    {
      int count = (pParse->nested==0);    /* True to count changes */
      sqlite3GenerateRowDelete(pParse, pTab, iCur, iRowid, count, pTrigger, OE_Default);
    }
................................................................................
      sqlite3VdbeAddOp2(v, OP_SCopy, regBase+nCol, regBase+j);
    }else{
      sqlite3VdbeAddOp3(v, OP_Column, iCur, idx, regBase+j);
      sqlite3ColumnDefault(v, pTab, idx, -1);
    }
  }
  if( doMakeRec ){






    sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol+1, regOut);
    sqlite3VdbeChangeP4(v, -1, sqlite3IndexAffinityStr(v, pIdx), P4_TRANSIENT);
  }
  sqlite3ReleaseTempRange(pParse, regBase, nCol+1);
  return regBase;
}

/************** End of delete.c **********************************************/
/************** Begin file func.c ********************************************/
................................................................................
/*
** For LIKE and GLOB matching on EBCDIC machines, assume that every
** character is exactly one byte in size.  Also, all characters are
** able to participate in upper-case-to-lower-case mappings in EBCDIC
** whereas only characters less than 0x80 do in ASCII.
*/
#if defined(SQLITE_EBCDIC)
# define sqlite3Utf8Read(A,C)    (*(A++))
# define GlogUpperToLower(A)     A = sqlite3UpperToLower[A]
#else
# define GlogUpperToLower(A)     if( A<0x80 ){ A = sqlite3UpperToLower[A]; }
#endif

static const struct compareInfo globInfo = { '*', '?', '[', 0 };
/* The correct SQL-92 behavior is for the LIKE operator to ignore
** case.  Thus  'a' LIKE 'A' would be true. */
static const struct compareInfo likeInfoNorm = { '%', '_',   0, 1 };
/* If SQLITE_CASE_SENSITIVE_LIKE is defined, then the LIKE operator
................................................................................
**
**         abc[*]xyz        Matches "abc*xyz" only
*/
static int patternCompare(
  const u8 *zPattern,              /* The glob pattern */
  const u8 *zString,               /* The string to compare against the glob */
  const struct compareInfo *pInfo, /* Information about how to do the compare */
  const int esc                    /* The escape character */
){
  int c, c2;
  int invert;
  int seen;
  u8 matchOne = pInfo->matchOne;
  u8 matchAll = pInfo->matchAll;
  u8 matchSet = pInfo->matchSet;
  u8 noCase = pInfo->noCase; 
  int prevEscape = 0;     /* True if the previous character was 'escape' */
................................................................................
      }
      return 0;
    }else if( !prevEscape && c==matchOne ){
      if( sqlite3Utf8Read(zString, &zString)==0 ){
        return 0;
      }
    }else if( c==matchSet ){
      int prior_c = 0;
      assert( esc==0 );    /* This only occurs for GLOB, not LIKE */
      seen = 0;
      invert = 0;
      c = sqlite3Utf8Read(zString, &zString);
      if( c==0 ) return 0;
      c2 = sqlite3Utf8Read(zPattern, &zPattern);
      if( c2=='^' ){
................................................................................
*/
static void likeFunc(
  sqlite3_context *context, 
  int argc, 
  sqlite3_value **argv
){
  const unsigned char *zA, *zB;
  int escape = 0;
  int nPat;
  sqlite3 *db = sqlite3_context_db_handle(context);

  zB = sqlite3_value_text(argv[0]);
  zA = sqlite3_value_text(argv[1]);

  /* Limit the length of the LIKE or GLOB pattern to avoid problems
................................................................................
      for(i=0; i<nCol; i++){
        sqlite3VdbeAddOp2(v, OP_Copy, aiCol[i]+1+regData, regTemp+i);
      }
  
      /* If the parent table is the same as the child table, and we are about
      ** to increment the constraint-counter (i.e. this is an INSERT operation),
      ** then check if the row being inserted matches itself. If so, do not
      ** increment the constraint-counter.  */






      if( pTab==pFKey->pFrom && nIncr==1 ){
        int iJump = sqlite3VdbeCurrentAddr(v) + nCol + 1;
        for(i=0; i<nCol; i++){
          int iChild = aiCol[i]+1+regData;
          int iParent = pIdx->aiColumn[i]+1+regData;





          sqlite3VdbeAddOp3(v, OP_Ne, iChild, iJump, iParent);

        }
        sqlite3VdbeAddOp2(v, OP_Goto, 0, iOk);
      }
  
      sqlite3VdbeAddOp3(v, OP_MakeRecord, regTemp, nCol, regRec);
      sqlite3VdbeChangeP4(v, -1, sqlite3IndexAffinityStr(v,pIdx), P4_TRANSIENT);
      sqlite3VdbeAddOp4Int(v, OP_Found, iCur, iOk, regRec, 0);
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code used to implement the PRAGMA command.
*/

/* Ignore this whole file if pragmas are disabled
*/
#if !defined(SQLITE_OMIT_PRAGMA)

/*
** Interpret the given string as a safety level.  Return 0 for OFF,
** 1 for ON or NORMAL and 2 for FULL.  Return 1 for an empty or 
** unrecognized string argument.
**
** Note that the values returned are one less that the values that
** should be passed into sqlite3BtreeSetSafetyLevel().  The is done
................................................................................

/*
** Interpret the given string as a boolean value.
*/
SQLITE_PRIVATE u8 sqlite3GetBoolean(const char *z){
  return getSafetyLevel(z)&1;
}







/*
** Interpret the given string as a locking mode value.
*/
static int getLockingMode(const char *z){
  if( z ){
    if( 0==sqlite3StrICmp(z, "exclusive") ) return PAGER_LOCKINGMODE_EXCLUSIVE;
................................................................................
    z = sqlite3DbStrNDup(db, (char*)pAll->z, pAll->n);
    sqlite3NestedParse(pParse,
       "INSERT INTO %Q.%s VALUES('trigger',%Q,%Q,0,'CREATE TRIGGER %q')",
       db->aDb[iDb].zName, SCHEMA_TABLE(iDb), zName,
       pTrig->table, z);
    sqlite3DbFree(db, z);
    sqlite3ChangeCookie(pParse, iDb);
    sqlite3VdbeAddOp4(v, OP_ParseSchema, iDb, 0, 0, sqlite3MPrintf(
        db, "type='trigger' AND name='%q'", zName), P4_DYNAMIC
    );
  }

  if( db->init.busy ){
    Trigger *pLink = pTrig;
    Hash *pHash = &db->aDb[iDb].pSchema->trigHash;
    assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
    pTrig = sqlite3HashInsert(pHash, zName, sqlite3Strlen30(zName), pTrig);
................................................................................
  for(nIdx=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nIdx++){}
  if( nIdx>0 ){
    aRegIdx = sqlite3DbMallocRaw(db, sizeof(Index*) * nIdx );
    if( aRegIdx==0 ) goto update_cleanup;
  }
  for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
    int reg;
    if( chngRowid ){
      reg = ++pParse->nMem;
    }else{
      reg = 0;
      for(i=0; i<pIdx->nColumn; i++){
        if( aXRef[pIdx->aiColumn[i]]>=0 ){
          reg = ++pParse->nMem;
          break;
................................................................................
    );
    sqlite3DbFree(db, zStmt);
    v = sqlite3GetVdbe(pParse);
    sqlite3ChangeCookie(pParse, iDb);

    sqlite3VdbeAddOp2(v, OP_Expire, 0, 0);
    zWhere = sqlite3MPrintf(db, "name='%q' AND type='table'", pTab->zName);
    sqlite3VdbeAddOp4(v, OP_ParseSchema, iDb, 0, 0, zWhere, P4_DYNAMIC);
    sqlite3VdbeAddOp4(v, OP_VCreate, iDb, 0, 0, 
                         pTab->zName, sqlite3Strlen30(pTab->zName) + 1);
  }

  /* If we are rereading the sqlite_master table create the in-memory
  ** record of the table. The xConnect() method is not called until
  ** the first time the virtual table is used in an SQL statement. This
................................................................................
      return i;
    }
#ifndef SQLITE_OMIT_BLOB_LITERAL
    case 'x': case 'X': {
      testcase( z[0]=='x' ); testcase( z[0]=='X' );
      if( z[1]=='\'' ){
        *tokenType = TK_BLOB;
        for(i=2; (c=z[i])!=0 && c!='\''; i++){
          if( !sqlite3Isxdigit(c) ){
            *tokenType = TK_ILLEGAL;
          }
        }
        if( i%2 || !c ) *tokenType = TK_ILLEGAL;
        if( c ) i++;
        return i;
      }
      /* Otherwise fall through to the next case */
    }
#endif
    default: {
      if( !IdChar(*z) ){
................................................................................
  if( pEngine==0 ){
    db->mallocFailed = 1;
    return SQLITE_NOMEM;
  }
  assert( pParse->pNewTable==0 );
  assert( pParse->pNewTrigger==0 );
  assert( pParse->nVar==0 );
  assert( pParse->nVarExpr==0 );
  assert( pParse->nVarExprAlloc==0 );
  assert( pParse->apVarExpr==0 );
  enableLookaside = db->lookaside.bEnabled;
  if( db->lookaside.pStart ) db->lookaside.bEnabled = 1;
  while( !db->mallocFailed && zSql[i]!=0 ){
    assert( i>=0 );
    pParse->sLastToken.z = &zSql[i];
    pParse->sLastToken.n = sqlite3GetToken((unsigned char*)&zSql[i],&tokenType);
    i += pParse->sLastToken.n;
................................................................................
    ** structure built up in pParse->pNewTable. The calling code (see vtab.c)
    ** will take responsibility for freeing the Table structure.
    */
    sqlite3DeleteTable(db, pParse->pNewTable);
  }

  sqlite3DeleteTrigger(db, pParse->pNewTrigger);

  sqlite3DbFree(db, pParse->apVarExpr);
  sqlite3DbFree(db, pParse->aAlias);
  while( pParse->pAinc ){
    AutoincInfo *p = pParse->pAinc;
    pParse->pAinc = p->pNext;
    sqlite3DbFree(db, p);
  }
  while( pParse->pZombieTab ){
................................................................................
      if( nOpt==3 && memcmp("vfs", zOpt, 3)==0 ){
        zVfs = zVal;
      }else{
        struct OpenMode {
          const char *z;
          int mode;
        } *aMode = 0;
        char *zModeType;
        int mask;
        int limit;

        if( nOpt==5 && memcmp("cache", zOpt, 5)==0 ){
          static struct OpenMode aCacheMode[] = {
            { "shared",  SQLITE_OPEN_SHAREDCACHE },
            { "private", SQLITE_OPEN_PRIVATECACHE },
            { 0, 0 }
          };
................................................................................
      ppNew = va_arg(ap, void**);
      pFree = va_arg(ap, void*);
      if( sz ) *ppNew = sqlite3ScratchMalloc(sz);
      sqlite3ScratchFree(pFree);
      break;
    }












  }
  va_end(ap);
#endif /* SQLITE_OMIT_BUILTIN_TEST */
  return rc;
}

/*
................................................................................
** older data.
**
** TODO(shess) Provide a VACUUM type operation to clear out all
** deletions and duplications.  This would basically be a forced merge
** into a single segment.
*/

#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

#if defined(SQLITE_ENABLE_FTS3) && !defined(SQLITE_CORE)
# define SQLITE_CORE 1
#endif

/************** Include fts3Int.h in the middle of fts3.c ********************/
/************** Begin file fts3Int.h *****************************************/
/*
** 2009 Nov 12
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
................................................................................
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
*/

#ifndef _FTSINT_H
#define _FTSINT_H

#if !defined(NDEBUG) && !defined(SQLITE_DEBUG) 
# define NDEBUG 1
#endif











/************** Include fts3_tokenizer.h in the middle of fts3Int.h **********/
/************** Begin file fts3_tokenizer.h **********************************/
/*
** 2006 July 10
**
** The author disclaims copyright to this source code.
**
................................................................................
/*
** Macro to return the number of elements in an array. SQLite has a
** similar macro called ArraySize(). Use a different name to avoid
** a collision when building an amalgamation with built-in FTS3.
*/
#define SizeofArray(X) ((int)(sizeof(X)/sizeof(X[0])))






/*
** Maximum length of a varint encoded integer. The varint format is different
** from that used by SQLite, so the maximum length is 10, not 9.
*/
#define FTS3_VARINT_MAX 10



















/*
** The testcase() macro is only used by the amalgamation.  If undefined,
** make it a no-op.
*/
#ifndef testcase
# define testcase(X)
#endif
................................................................................

typedef struct Fts3Table Fts3Table;
typedef struct Fts3Cursor Fts3Cursor;
typedef struct Fts3Expr Fts3Expr;
typedef struct Fts3Phrase Fts3Phrase;
typedef struct Fts3PhraseToken Fts3PhraseToken;


typedef struct Fts3SegFilter Fts3SegFilter;
typedef struct Fts3DeferredToken Fts3DeferredToken;
typedef struct Fts3SegReader Fts3SegReader;
typedef struct Fts3SegReaderCursor Fts3SegReaderCursor;

/*
** A connection to a fulltext index is an instance of the following
** structure. The xCreate and xConnect methods create an instance
** of this structure and xDestroy and xDisconnect free that instance.
** All other methods receive a pointer to the structure as one of their
** arguments.
................................................................................
  int nColumn;                    /* number of named columns in virtual table */
  char **azColumn;                /* column names.  malloced */
  sqlite3_tokenizer *pTokenizer;  /* tokenizer for inserts and queries */

  /* Precompiled statements used by the implementation. Each of these 
  ** statements is run and reset within a single virtual table API call. 
  */
  sqlite3_stmt *aStmt[24];

  char *zReadExprlist;
  char *zWriteExprlist;

  int nNodeSize;                  /* Soft limit for node size */
  u8 bHasStat;                    /* True if %_stat table exists */
  u8 bHasDocsize;                 /* True if %_docsize table exists */

  int nPgsz;                      /* Page size for host database */
  char *zSegmentsTbl;             /* Name of %_segments table */
  sqlite3_blob *pSegments;        /* Blob handle open on %_segments table */



  /* The following hash table is used to buffer pending index updates during
  ** transactions. Variable nPendingData estimates the memory size of the 
  ** pending data, including hash table overhead, but not malloc overhead. 
  ** When nPendingData exceeds nMaxPendingData, the buffer is flushed 
  ** automatically. Variable iPrevDocid is the docid of the most recently
  ** inserted record.





  */





  int nMaxPendingData;
  int nPendingData;
  sqlite_int64 iPrevDocid;
  Fts3Hash pendingTerms;

#if defined(SQLITE_DEBUG)
  /* State variables used for validating that the transaction control
  ** methods of the virtual table are called at appropriate times.  These
  ** values do not contribution to the FTS computation; they are used for
  ** verifying the SQLite core.
  */
................................................................................
  Fts3Expr *pExpr;                /* Parsed MATCH query string */
  int nPhrase;                    /* Number of matchable phrases in query */
  Fts3DeferredToken *pDeferred;   /* Deferred search tokens, if any */
  sqlite3_int64 iPrevId;          /* Previous id read from aDoclist */
  char *pNextId;                  /* Pointer into the body of aDoclist */
  char *aDoclist;                 /* List of docids for full-text queries */
  int nDoclist;                   /* Size of buffer at aDoclist */
  int desc;                       /* True to sort in descending order */
  int eEvalmode;                  /* An FTS3_EVAL_XX constant */
  int nRowAvg;                    /* Average size of database rows, in pages */


  int isMatchinfoNeeded;          /* True when aMatchinfo[] needs filling in */
  u32 *aMatchinfo;                /* Information about most recent match */
  int nMatchinfo;                 /* Number of elements in aMatchinfo[] */
  char *zMatchinfo;               /* Matchinfo specification */
};

................................................................................
** indicating that all columns should be searched,
** then eSearch would be set to FTS3_FULLTEXT_SEARCH+4.
*/
#define FTS3_FULLSCAN_SEARCH 0    /* Linear scan of %_content table */
#define FTS3_DOCID_SEARCH    1    /* Lookup by rowid on %_content table */
#define FTS3_FULLTEXT_SEARCH 2    /* Full-text index search */













/*
** A "phrase" is a sequence of one or more tokens that must match in
** sequence.  A single token is the base case and the most common case.
** For a sequence of tokens contained in double-quotes (i.e. "one two three")
** nToken will be the number of tokens in the string.
**
** The nDocMatch and nMatch variables contain data that may be used by the
** matchinfo() function. They are populated when the full-text index is 
** queried for hits on the phrase. If one or more tokens in the phrase
** are deferred, the nDocMatch and nMatch variables are populated based
** on the assumption that the 
*/
struct Fts3PhraseToken {
  char *z;                        /* Text of the token */
  int n;                          /* Number of bytes in buffer z */
  int isPrefix;                   /* True if token ends with a "*" character */
  int bFulltext;                  /* True if full-text index was used */

  Fts3SegReaderCursor *pSegcsr;   /* Segment-reader for this token */


  Fts3DeferredToken *pDeferred;   /* Deferred token object for this token */

};

struct Fts3Phrase {





  /* Variables populated by fts3_expr.c when parsing a MATCH expression */


  int nToken;                /* Number of tokens in the phrase */
  int iColumn;               /* Index of column this phrase must match */
  int isNot;                 /* Phrase prefixed by unary not (-) operator */
  Fts3PhraseToken aToken[1]; /* One entry for each token in the phrase */
};

/*
** A tree of these objects forms the RHS of a MATCH operator.
**
** If Fts3Expr.eType is either FTSQUERY_NEAR or FTSQUERY_PHRASE and isLoaded
** is true, then aDoclist points to a malloced buffer, size nDoclist bytes, 
** containing the results of the NEAR or phrase query in FTS3 doclist
** format. As usual, the initial "Length" field found in doclists stored
** on disk is omitted from this buffer.
**
** Variable pCurrent always points to the start of a docid field within
** aDoclist. Since the doclist is usually scanned in docid order, this can
** be used to accelerate seeking to the required docid within the doclist.








*/
struct Fts3Expr {
  int eType;                 /* One of the FTSQUERY_XXX values defined below */
  int nNear;                 /* Valid if eType==FTSQUERY_NEAR */
  Fts3Expr *pParent;         /* pParent->pLeft==this or pParent->pRight==this */
  Fts3Expr *pLeft;           /* Left operand */
  Fts3Expr *pRight;          /* Right operand */
  Fts3Phrase *pPhrase;       /* Valid if eType==FTSQUERY_PHRASE */

  int isLoaded;              /* True if aDoclist/nDoclist are initialized. */
  char *aDoclist;            /* Buffer containing doclist */
  int nDoclist;              /* Size of aDoclist in bytes */



  sqlite3_int64 iCurrent;
  char *pCurrent;

};

/*
** Candidate values for Fts3Query.eType. Note that the order of the first
** four values is in order of precedence when parsing expressions. For 
** example, the following:
**
................................................................................
/* fts3_write.c */
SQLITE_PRIVATE int sqlite3Fts3UpdateMethod(sqlite3_vtab*,int,sqlite3_value**,sqlite3_int64*);
SQLITE_PRIVATE int sqlite3Fts3PendingTermsFlush(Fts3Table *);
SQLITE_PRIVATE void sqlite3Fts3PendingTermsClear(Fts3Table *);
SQLITE_PRIVATE int sqlite3Fts3Optimize(Fts3Table *);
SQLITE_PRIVATE int sqlite3Fts3SegReaderNew(int, sqlite3_int64,
  sqlite3_int64, sqlite3_int64, const char *, int, Fts3SegReader**);
SQLITE_PRIVATE int sqlite3Fts3SegReaderPending(Fts3Table*,const char*,int,int,Fts3SegReader**);

SQLITE_PRIVATE void sqlite3Fts3SegReaderFree(Fts3SegReader *);
SQLITE_PRIVATE int sqlite3Fts3SegReaderCost(Fts3Cursor *, Fts3SegReader *, int *);
SQLITE_PRIVATE int sqlite3Fts3AllSegdirs(Fts3Table*, int, sqlite3_stmt **);
SQLITE_PRIVATE int sqlite3Fts3ReadLock(Fts3Table *);
SQLITE_PRIVATE int sqlite3Fts3ReadBlock(Fts3Table*, sqlite3_int64, char **, int*);

SQLITE_PRIVATE int sqlite3Fts3SelectDoctotal(Fts3Table *, sqlite3_stmt **);
SQLITE_PRIVATE int sqlite3Fts3SelectDocsize(Fts3Table *, sqlite3_int64, sqlite3_stmt **);

SQLITE_PRIVATE void sqlite3Fts3FreeDeferredTokens(Fts3Cursor *);
SQLITE_PRIVATE int sqlite3Fts3DeferToken(Fts3Cursor *, Fts3PhraseToken *, int);
SQLITE_PRIVATE int sqlite3Fts3CacheDeferredDoclists(Fts3Cursor *);
SQLITE_PRIVATE void sqlite3Fts3FreeDeferredDoclists(Fts3Cursor *);
SQLITE_PRIVATE char *sqlite3Fts3DeferredDoclist(Fts3DeferredToken *, int *);
SQLITE_PRIVATE void sqlite3Fts3SegmentsClose(Fts3Table *);


#define FTS3_SEGCURSOR_PENDING -1
#define FTS3_SEGCURSOR_ALL     -2

SQLITE_PRIVATE int sqlite3Fts3SegReaderStart(Fts3Table*, Fts3SegReaderCursor*, Fts3SegFilter*);
SQLITE_PRIVATE int sqlite3Fts3SegReaderStep(Fts3Table *, Fts3SegReaderCursor *);
SQLITE_PRIVATE void sqlite3Fts3SegReaderFinish(Fts3SegReaderCursor *);

SQLITE_PRIVATE int sqlite3Fts3SegReaderCursor(
    Fts3Table *, int, const char *, int, int, int, Fts3SegReaderCursor *);

/* Flags allowed as part of the 4th argument to SegmentReaderIterate() */
#define FTS3_SEGMENT_REQUIRE_POS   0x00000001
#define FTS3_SEGMENT_IGNORE_EMPTY  0x00000002
#define FTS3_SEGMENT_COLUMN_FILTER 0x00000004
#define FTS3_SEGMENT_PREFIX        0x00000008
#define FTS3_SEGMENT_SCAN          0x00000010
................................................................................
struct Fts3SegFilter {
  const char *zTerm;
  int nTerm;
  int iCol;
  int flags;
};

struct Fts3SegReaderCursor {
  /* Used internally by sqlite3Fts3SegReaderXXX() calls */
  Fts3SegReader **apSegment;      /* Array of Fts3SegReader objects */
  int nSegment;                   /* Size of apSegment array */
  int nAdvance;                   /* How many seg-readers to advance */
  Fts3SegFilter *pFilter;         /* Pointer to filter object */
  char *aBuffer;                  /* Buffer to merge doclists in */
  int nBuffer;                    /* Allocated size of aBuffer[] in bytes */




  /* Cost of running this iterator. Used by fts3.c only. */
  int nCost;



  /* Output values. Valid only after Fts3SegReaderStep() returns SQLITE_ROW. */
  char *zTerm;                    /* Pointer to term buffer */
  int nTerm;                      /* Size of zTerm in bytes */
  char *aDoclist;                 /* Pointer to doclist buffer */
  int nDoclist;                   /* Size of aDoclist[] in bytes */
};
................................................................................

/* fts3.c */
SQLITE_PRIVATE int sqlite3Fts3PutVarint(char *, sqlite3_int64);
SQLITE_PRIVATE int sqlite3Fts3GetVarint(const char *, sqlite_int64 *);
SQLITE_PRIVATE int sqlite3Fts3GetVarint32(const char *, int *);
SQLITE_PRIVATE int sqlite3Fts3VarintLen(sqlite3_uint64);
SQLITE_PRIVATE void sqlite3Fts3Dequote(char *);


SQLITE_PRIVATE char *sqlite3Fts3FindPositions(Fts3Cursor *, Fts3Expr *, sqlite3_int64, int);
SQLITE_PRIVATE int sqlite3Fts3ExprLoadDoclist(Fts3Cursor *, Fts3Expr *);
SQLITE_PRIVATE int sqlite3Fts3ExprLoadFtDoclist(Fts3Cursor *, Fts3Expr *, char **, int *);
SQLITE_PRIVATE int sqlite3Fts3ExprNearTrim(Fts3Expr *, Fts3Expr *, int);

/* fts3_tokenizer.c */
SQLITE_PRIVATE const char *sqlite3Fts3NextToken(const char *, int *);
SQLITE_PRIVATE int sqlite3Fts3InitHashTable(sqlite3 *, Fts3Hash *, const char *);
SQLITE_PRIVATE int sqlite3Fts3InitTokenizer(Fts3Hash *pHash, const char *, 
    sqlite3_tokenizer **, char **
);
................................................................................
SQLITE_PRIVATE int sqlite3Fts3ExprInitTestInterface(sqlite3 *db);
SQLITE_PRIVATE int sqlite3Fts3InitTerm(sqlite3 *db);
#endif

/* fts3_aux.c */
SQLITE_PRIVATE int sqlite3Fts3InitAux(sqlite3 *db);

























#endif /* _FTSINT_H */

/************** End of fts3Int.h *********************************************/
/************** Continuing where we left off in fts3.c ***********************/







#ifndef SQLITE_CORE 
  SQLITE_EXTENSION_INIT1
#endif

/* 
................................................................................
  *pVal += iVal;
}

/*
** When this function is called, *pp points to the first byte following a
** varint that is part of a doclist (or position-list, or any other list
** of varints). This function moves *pp to point to the start of that varint,
** and decrements the value stored in *pVal by the varint value.
**
** Argument pStart points to the first byte of the doclist that the
** varint is part of.
*/
static void fts3GetReverseDeltaVarint(
  char **pp, 
  char *pStart, 
  sqlite3_int64 *pVal
){
  sqlite3_int64 iVal;
  char *p = *pp;

................................................................................
  ** interested in. So, unless the doclist is corrupt, the 0x80 bit is
  ** clear on character p[-1]. */
  for(p = (*pp)-2; p>=pStart && *p&0x80; p--);
  p++;
  *pp = p;

  sqlite3Fts3GetVarint(p, &iVal);
  *pVal -= iVal;
}

/*
** As long as *pp has not reached its end (pEnd), then do the same
** as fts3GetDeltaVarint(): read a single varint and add it to *pVal.
** But if we have reached the end of the varint, just set *pp=0 and
** leave *pVal unchanged.
*/
static void fts3GetDeltaVarint2(char **pp, char *pEnd, sqlite3_int64 *pVal){
  if( *pp>=pEnd ){
    *pp = 0;
  }else{
    fts3GetDeltaVarint(pp, pVal);
  }
}

/*
** The xDisconnect() virtual table method.
*/
static int fts3DisconnectMethod(sqlite3_vtab *pVtab){
  Fts3Table *p = (Fts3Table *)pVtab;
................................................................................
      rc = SQLITE_NOMEM;
    }else{
      rc = sqlite3_prepare(p->db, zSql, -1, &pStmt, 0);
      if( rc==SQLITE_OK ){
        sqlite3_step(pStmt);
        p->nPgsz = sqlite3_column_int(pStmt, 0);
        rc = sqlite3_finalize(pStmt);



      }
    }
    assert( p->nPgsz>0 || rc!=SQLITE_OK );
    sqlite3_free(zSql);
    *pRc = rc;
  }
}
................................................................................
  fts3Appendf(pRc, &zRet, "?");
  for(i=0; i<p->nColumn; i++){
    fts3Appendf(pRc, &zRet, ",%s(?)", zFunction);
  }
  sqlite3_free(zFree);
  return zRet;
}





















































/*
** This function is the implementation of both the xConnect and xCreate
** methods of the FTS3 virtual table.
**
** The argv[] array contains the following:
**
................................................................................
  int iCol;                       /* Column index */
  int nString = 0;                /* Bytes required to hold all column names */
  int nCol = 0;                   /* Number of columns in the FTS table */
  char *zCsr;                     /* Space for holding column names */
  int nDb;                        /* Bytes required to hold database name */
  int nName;                      /* Bytes required to hold table name */
  int isFts4 = (argv[0][3]=='4'); /* True for FTS4, false for FTS3 */
  int bNoDocsize = 0;             /* True to omit %_docsize table */
  const char **aCol;              /* Array of column names */
  sqlite3_tokenizer *pTokenizer = 0;        /* Tokenizer for this table */









  char *zCompress = 0;
  char *zUncompress = 0;

  assert( strlen(argv[0])==4 );
  assert( (sqlite3_strnicmp(argv[0], "fts4", 4)==0 && isFts4)
       || (sqlite3_strnicmp(argv[0], "fts3", 4)==0 && !isFts4)
  );

  nDb = (int)strlen(argv[1]) + 1;
................................................................................
     && 0==sqlite3Fts3IsIdChar(z[8])
    ){
      rc = sqlite3Fts3InitTokenizer(pHash, &z[9], &pTokenizer, pzErr);
    }

    /* Check if it is an FTS4 special argument. */
    else if( isFts4 && fts3IsSpecialColumn(z, &nKey, &zVal) ){













      if( !zVal ){
        rc = SQLITE_NOMEM;
        goto fts3_init_out;





      }
      if( nKey==9 && 0==sqlite3_strnicmp(z, "matchinfo", 9) ){
        if( strlen(zVal)==4 && 0==sqlite3_strnicmp(zVal, "fts3", 4) ){
          bNoDocsize = 1;




        }else{



          *pzErr = sqlite3_mprintf("unrecognized matchinfo: %s", zVal);
          rc = SQLITE_ERROR;
        }
      }else if( nKey==8 && 0==sqlite3_strnicmp(z, "compress", 8) ){











        zCompress = zVal;
        zVal = 0;
      }else if( nKey==10 && 0==sqlite3_strnicmp(z, "uncompress", 10) ){




        zUncompress = zVal;
        zVal = 0;
      }else{






        *pzErr = sqlite3_mprintf("unrecognized parameter: %s", z);
        rc = SQLITE_ERROR;
      }




      sqlite3_free(zVal);

    }

    /* Otherwise, the argument is a column name. */
    else {
      nString += (int)(strlen(z) + 1);
      aCol[nCol++] = z;
    }
................................................................................

  if( pTokenizer==0 ){
    rc = sqlite3Fts3InitTokenizer(pHash, "simple", &pTokenizer, pzErr);
    if( rc!=SQLITE_OK ) goto fts3_init_out;
  }
  assert( pTokenizer );








  /* Allocate and populate the Fts3Table structure. */
  nByte = sizeof(Fts3Table) +              /* Fts3Table */
          nCol * sizeof(char *) +              /* azColumn */

          nName +                              /* zName */
          nDb +                                /* zDb */
          nString;                             /* Space for azColumn strings */
  p = (Fts3Table*)sqlite3_malloc(nByte);
  if( p==0 ){
    rc = SQLITE_NOMEM;
    goto fts3_init_out;
................................................................................
  }
  memset(p, 0, nByte);
  p->db = db;
  p->nColumn = nCol;
  p->nPendingData = 0;
  p->azColumn = (char **)&p[1];
  p->pTokenizer = pTokenizer;
  p->nNodeSize = 1000;
  p->nMaxPendingData = FTS3_MAX_PENDING_DATA;
  p->bHasDocsize = (isFts4 && bNoDocsize==0);
  p->bHasStat = isFts4;

  TESTONLY( p->inTransaction = -1 );
  TESTONLY( p->mxSavepoint = -1 );





  fts3HashInit(&p->pendingTerms, FTS3_HASH_STRING, 1);


  /* Fill in the zName and zDb fields of the vtab structure. */
  zCsr = (char *)&p->azColumn[nCol];
  p->zName = zCsr;
  memcpy(zCsr, argv[2], nName);
  zCsr += nName;
  p->zDb = zCsr;
  memcpy(zCsr, argv[1], nDb);
  zCsr += nDb;

  /* Fill in the azColumn array */
  for(iCol=0; iCol<nCol; iCol++){
    char *z; 
    int n;
    z = (char *)sqlite3Fts3NextToken(aCol[iCol], &n);
    memcpy(zCsr, z, n);
    zCsr[n] = '\0';
    sqlite3Fts3Dequote(zCsr);
    p->azColumn[iCol] = zCsr;
    zCsr += n+1;
    assert( zCsr <= &((char *)p)[nByte] );
................................................................................
  ** database. TODO: For xConnect(), it could verify that said tables exist.
  */
  if( isCreate ){
    rc = fts3CreateTables(p);
  }

  /* Figure out the page-size for the database. This is required in order to
  ** estimate the cost of loading large doclists from the database (see 
  ** function sqlite3Fts3SegReaderCost() for details).
  */
  fts3DatabasePageSize(&rc, p);


  /* Declare the table schema to SQLite. */
  fts3DeclareVtab(&rc, p);

fts3_init_out:


  sqlite3_free(zCompress);
  sqlite3_free(zUncompress);
  sqlite3_free((void *)aCol);
  if( rc!=SQLITE_OK ){
    if( p ){
      fts3DisconnectMethod((sqlite3_vtab *)p);
    }else if( pTokenizer ){
      pTokenizer->pModule->xDestroy(pTokenizer);
    }
  }else{

    *ppVTab = &p->base;
  }
  return rc;
}

/*
** The xConnect() and xCreate() methods for the virtual table. All the
................................................................................
    struct sqlite3_index_orderby *pOrder = &pInfo->aOrderBy[0];
    if( pOrder->iColumn<0 || pOrder->iColumn==p->nColumn+1 ){
      if( pOrder->desc ){
        pInfo->idxStr = "DESC";
      }else{
        pInfo->idxStr = "ASC";
      }
    }
    pInfo->orderByConsumed = 1;
  }



  return SQLITE_OK;
}

/*
** Implementation of xOpen method.
*/
static int fts3OpenMethod(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCsr){
................................................................................
  Fts3Cursor *pCsr = (Fts3Cursor *)pCursor;
  assert( ((Fts3Table *)pCsr->base.pVtab)->pSegments==0 );
  sqlite3_finalize(pCsr->pStmt);
  sqlite3Fts3ExprFree(pCsr->pExpr);
  sqlite3Fts3FreeDeferredTokens(pCsr);
  sqlite3_free(pCsr->aDoclist);
  sqlite3_free(pCsr->aMatchinfo);

  sqlite3_free(pCsr);
  return SQLITE_OK;
}

/*
** Position the pCsr->pStmt statement so that it is on the row
** of the %_content table that contains the last match.  Return
** SQLITE_OK on success.  
*/
static int fts3CursorSeek(sqlite3_context *pContext, Fts3Cursor *pCsr){
  if( pCsr->isRequireSeek ){
    pCsr->isRequireSeek = 0;
    sqlite3_bind_int64(pCsr->pStmt, 1, pCsr->iPrevId);

    if( SQLITE_ROW==sqlite3_step(pCsr->pStmt) ){
      return SQLITE_OK;
    }else{
      int rc = sqlite3_reset(pCsr->pStmt);
      if( rc==SQLITE_OK ){
        /* If no row was found and no error has occured, then the %_content
        ** table is missing a row that is present in the full-text index.
................................................................................
  assert( !piLeaf2 || !piLeaf || rc!=SQLITE_OK || (*piLeaf<=*piLeaf2) );

  if( rc==SQLITE_OK && iHeight>1 ){
    char *zBlob = 0;              /* Blob read from %_segments table */
    int nBlob;                    /* Size of zBlob in bytes */

    if( piLeaf && piLeaf2 && (*piLeaf!=*piLeaf2) ){
      rc = sqlite3Fts3ReadBlock(p, *piLeaf, &zBlob, &nBlob);
      if( rc==SQLITE_OK ){
        rc = fts3SelectLeaf(p, zTerm, nTerm, zBlob, nBlob, piLeaf, 0);
      }
      sqlite3_free(zBlob);
      piLeaf = 0;
      zBlob = 0;
    }

    if( rc==SQLITE_OK ){
      rc = sqlite3Fts3ReadBlock(p, piLeaf ? *piLeaf : *piLeaf2, &zBlob, &nBlob);
    }
    if( rc==SQLITE_OK ){
      rc = fts3SelectLeaf(p, zTerm, nTerm, zBlob, nBlob, piLeaf, piLeaf2);
    }
    sqlite3_free(zBlob);
  }

................................................................................
  }
  *p++ = 0x00;
  *pp = p;
  return 1;
}

/*
** Merge two position-lists as required by the NEAR operator.












*/
static int fts3PoslistNearMerge(
  char **pp,                      /* Output buffer */
  char *aTmp,                     /* Temporary buffer space */
  int nRight,                     /* Maximum difference in token positions */
  int nLeft,                      /* Maximum difference in token positions */
  char **pp1,                     /* IN/OUT: Left input list */
  char **pp2                      /* IN/OUT: Right input list */
){
  char *p1 = *pp1;
  char *p2 = *pp2;

  if( !pp ){
    if( fts3PoslistPhraseMerge(0, nRight, 0, 0, pp1, pp2) ) return 1;
    *pp1 = p1;
    *pp2 = p2;
    return fts3PoslistPhraseMerge(0, nLeft, 0, 0, pp2, pp1);
  }else{
    char *pTmp1 = aTmp;
    char *pTmp2;
    char *aTmp2;
    int res = 1;

    fts3PoslistPhraseMerge(&pTmp1, nRight, 0, 0, pp1, pp2);
    aTmp2 = pTmp2 = pTmp1;
    *pp1 = p1;
    *pp2 = p2;
    fts3PoslistPhraseMerge(&pTmp2, nLeft, 1, 0, pp2, pp1);
    if( pTmp1!=aTmp && pTmp2!=aTmp2 ){
      fts3PoslistMerge(pp, &aTmp, &aTmp2);
    }else if( pTmp1!=aTmp ){
      fts3PoslistCopy(pp, &aTmp);
    }else if( pTmp2!=aTmp2 ){
      fts3PoslistCopy(pp, &aTmp2);
    }else{
      res = 0;
    }

    return res;
  }
}

/*
** Values that may be used as the first parameter to fts3DoclistMerge().


*/
#define MERGE_NOT        2        /* D + D -> D */
#define MERGE_AND        3        /* D + D -> D */
#define MERGE_OR         4        /* D + D -> D */
#define MERGE_POS_OR     5        /* P + P -> P */
#define MERGE_PHRASE     6        /* P + P -> D */
#define MERGE_POS_PHRASE 7        /* P + P -> P */
#define MERGE_NEAR       8        /* P + P -> D */
#define MERGE_POS_NEAR   9        /* P + P -> P */





/*
** Merge the two doclists passed in buffer a1 (size n1 bytes) and a2
** (size n2 bytes). The output is written to pre-allocated buffer aBuffer,
** which is guaranteed to be large enough to hold the results. The number
** of bytes written to aBuffer is stored in *pnBuffer before returning.
**


** If successful, SQLITE_OK is returned. Otherwise, if a malloc error
** occurs while allocating a temporary buffer as part of the merge operation,
** SQLITE_NOMEM is returned.
*/




































static int fts3DoclistMerge(
  int mergetype,                  /* One of the MERGE_XXX constants */
  int nParam1,                    /* Used by MERGE_NEAR and MERGE_POS_NEAR */
  int nParam2,                    /* Used by MERGE_NEAR and MERGE_POS_NEAR */
  char *aBuffer,                  /* Pre-allocated output buffer */
  int *pnBuffer,                  /* OUT: Bytes written to aBuffer */
  char *a1,                       /* Buffer containing first doclist */

  int n1,                         /* Size of buffer a1 */
  char *a2,                       /* Buffer containing second doclist */
  int n2,                         /* Size of buffer a2 */
  int *pnDoc                      /* OUT: Number of docids in output */

){
  sqlite3_int64 i1 = 0;
  sqlite3_int64 i2 = 0;
  sqlite3_int64 iPrev = 0;

  char *p = aBuffer;


  char *p1 = a1;
  char *p2 = a2;
  char *pEnd1 = &a1[n1];
  char *pEnd2 = &a2[n2];
  int nDoc = 0;


  assert( mergetype==MERGE_OR     || mergetype==MERGE_POS_OR 
       || mergetype==MERGE_AND    || mergetype==MERGE_NOT
       || mergetype==MERGE_PHRASE || mergetype==MERGE_POS_PHRASE
       || mergetype==MERGE_NEAR   || mergetype==MERGE_POS_NEAR
  );

  if( !aBuffer ){
    *pnBuffer = 0;


    return SQLITE_NOMEM;
  }

  /* Read the first docid from each doclist */

  fts3GetDeltaVarint2(&p1, pEnd1, &i1);
  fts3GetDeltaVarint2(&p2, pEnd2, &i2);

  switch( mergetype ){
    case MERGE_OR:
    case MERGE_POS_OR:
      while( p1 || p2 ){


        if( p2 && p1 && i1==i2 ){
          fts3PutDeltaVarint(&p, &iPrev, i1);
          if( mergetype==MERGE_POS_OR ) fts3PoslistMerge(&p, &p1, &p2);
          fts3GetDeltaVarint2(&p1, pEnd1, &i1);
          fts3GetDeltaVarint2(&p2, pEnd2, &i2);
        }else if( !p2 || (p1 && i1<i2) ){
          fts3PutDeltaVarint(&p, &iPrev, i1);
          if( mergetype==MERGE_POS_OR ) fts3PoslistCopy(&p, &p1);
          fts3GetDeltaVarint2(&p1, pEnd1, &i1);
        }else{
          fts3PutDeltaVarint(&p, &iPrev, i2);
          if( mergetype==MERGE_POS_OR ) fts3PoslistCopy(&p, &p2);
          fts3GetDeltaVarint2(&p2, pEnd2, &i2);
        }
      }
      break;

    case MERGE_AND:
      while( p1 && p2 ){
        if( i1==i2 ){
          fts3PutDeltaVarint(&p, &iPrev, i1);
          fts3GetDeltaVarint2(&p1, pEnd1, &i1);
          fts3GetDeltaVarint2(&p2, pEnd2, &i2);
          nDoc++;
        }else if( i1<i2 ){
          fts3GetDeltaVarint2(&p1, pEnd1, &i1);
        }else{
          fts3GetDeltaVarint2(&p2, pEnd2, &i2);
        }
      }
      break;

    case MERGE_NOT:
      while( p1 ){
        if( p2 && i1==i2 ){
          fts3GetDeltaVarint2(&p1, pEnd1, &i1);
          fts3GetDeltaVarint2(&p2, pEnd2, &i2);
        }else if( !p2 || i1<i2 ){
          fts3PutDeltaVarint(&p, &iPrev, i1);
          fts3GetDeltaVarint2(&p1, pEnd1, &i1);
        }else{
          fts3GetDeltaVarint2(&p2, pEnd2, &i2);
        }
      }

      break;


    case MERGE_POS_PHRASE:
    case MERGE_PHRASE: {
      char **ppPos = (mergetype==MERGE_PHRASE ? 0 : &p);
      while( p1 && p2 ){
        if( i1==i2 ){
          char *pSave = p;
          sqlite3_int64 iPrevSave = iPrev;
          fts3PutDeltaVarint(&p, &iPrev, i1);
          if( 0==fts3PoslistPhraseMerge(ppPos, nParam1, 0, 1, &p1, &p2) ){
            p = pSave;
            iPrev = iPrevSave;
          }else{
            nDoc++;
          }
          fts3GetDeltaVarint2(&p1, pEnd1, &i1);
          fts3GetDeltaVarint2(&p2, pEnd2, &i2);
        }else if( i1<i2 ){
          fts3PoslistCopy(0, &p1);
          fts3GetDeltaVarint2(&p1, pEnd1, &i1);
        }else{
          fts3PoslistCopy(0, &p2);
          fts3GetDeltaVarint2(&p2, pEnd2, &i2);
        }
      }
      break;
    }

    default: assert( mergetype==MERGE_POS_NEAR || mergetype==MERGE_NEAR ); {


      char *aTmp = 0;

      char **ppPos = 0;



      if( mergetype==MERGE_POS_NEAR ){
        ppPos = &p;
        aTmp = sqlite3_malloc(2*(n1+n2+1));
        if( !aTmp ){
          return SQLITE_NOMEM;

        }



      }

      while( p1 && p2 ){
        if( i1==i2 ){


          char *pSave = p;
          sqlite3_int64 iPrevSave = iPrev;
          fts3PutDeltaVarint(&p, &iPrev, i1);


          if( !fts3PoslistNearMerge(ppPos, aTmp, nParam1, nParam2, &p1, &p2) ){
            iPrev = iPrevSave;


            p = pSave;


          }

          fts3GetDeltaVarint2(&p1, pEnd1, &i1);
          fts3GetDeltaVarint2(&p2, pEnd2, &i2);
        }else if( i1<i2 ){
          fts3PoslistCopy(0, &p1);
          fts3GetDeltaVarint2(&p1, pEnd1, &i1);
        }else{
          fts3PoslistCopy(0, &p2);
          fts3GetDeltaVarint2(&p2, pEnd2, &i2);
        }
      }
      sqlite3_free(aTmp);
      break;
    }

  }

  if( pnDoc ) *pnDoc = nDoc;
  *pnBuffer = (int)(p-aBuffer);
  return SQLITE_OK;
}

/* 
** A pointer to an instance of this structure is used as the context 
** argument to sqlite3Fts3SegReaderIterate()
*/
typedef struct TermSelect TermSelect;
struct TermSelect {
  int isReqPos;
  char *aaOutput[16];             /* Malloc'd output buffer */
  int anOutput[16];               /* Size of output in bytes */
};

/*
** Merge all doclists in the TermSelect.aaOutput[] array into a single
** doclist stored in TermSelect.aaOutput[0]. If successful, delete all
** other doclists (except the aaOutput[0] one) and return SQLITE_OK.
**
** If an OOM error occurs, return SQLITE_NOMEM. In this case it is
** the responsibility of the caller to free any doclists left in the
** TermSelect.aaOutput[] array.
*/
static int fts3TermSelectMerge(TermSelect *pTS){
  int mergetype = (pTS->isReqPos ? MERGE_POS_OR : MERGE_OR);
  char *aOut = 0;
  int nOut = 0;
  int i;

  /* Loop through the doclists in the aaOutput[] array. Merge them all
  ** into a single doclist.
  */
................................................................................
  for(i=0; i<SizeofArray(pTS->aaOutput); i++){
    if( pTS->aaOutput[i] ){
      if( !aOut ){
        aOut = pTS->aaOutput[i];
        nOut = pTS->anOutput[i];
        pTS->aaOutput[i] = 0;
      }else{
        int nNew = nOut + pTS->anOutput[i];
        char *aNew = sqlite3_malloc(nNew);
        if( !aNew ){
          sqlite3_free(aOut);
          return SQLITE_NOMEM;
        }
        fts3DoclistMerge(mergetype, 0, 0,
            aNew, &nNew, pTS->aaOutput[i], pTS->anOutput[i], aOut, nOut, 0
        );


        sqlite3_free(pTS->aaOutput[i]);
        sqlite3_free(aOut);
        pTS->aaOutput[i] = 0;
        aOut = aNew;
        nOut = nNew;
      }
    }
................................................................................

  UNUSED_PARAMETER(p);
  UNUSED_PARAMETER(zTerm);
  UNUSED_PARAMETER(nTerm);

  if( pTS->aaOutput[0]==0 ){
    /* If this is the first term selected, copy the doclist to the output
    ** buffer using memcpy(). TODO: Add a way to transfer control of the
    ** aDoclist buffer from the caller so as to avoid the memcpy().
    */
    pTS->aaOutput[0] = sqlite3_malloc(nDoclist);
    pTS->anOutput[0] = nDoclist;
    if( pTS->aaOutput[0] ){
      memcpy(pTS->aaOutput[0], aDoclist, nDoclist);
    }else{
      return SQLITE_NOMEM;
    }
  }else{
    int mergetype = (pTS->isReqPos ? MERGE_POS_OR : MERGE_OR);
    char *aMerge = aDoclist;
    int nMerge = nDoclist;
    int iOut;

    for(iOut=0; iOut<SizeofArray(pTS->aaOutput); iOut++){
      char *aNew;
      int nNew;
      if( pTS->aaOutput[iOut]==0 ){
        assert( iOut>0 );
        pTS->aaOutput[iOut] = aMerge;
        pTS->anOutput[iOut] = nMerge;
        break;



      }


      nNew = nMerge + pTS->anOutput[iOut];
      aNew = sqlite3_malloc(nNew);
      if( !aNew ){
        if( aMerge!=aDoclist ){
          sqlite3_free(aMerge);
        }
        return SQLITE_NOMEM;
      }
      fts3DoclistMerge(mergetype, 0, 0, aNew, &nNew, 
          pTS->aaOutput[iOut], pTS->anOutput[iOut], aMerge, nMerge, 0
      );

      if( iOut>0 ) sqlite3_free(aMerge);
      sqlite3_free(pTS->aaOutput[iOut]);
      pTS->aaOutput[iOut] = 0;

      aMerge = aNew;
      nMerge = nNew;
      if( (iOut+1)==SizeofArray(pTS->aaOutput) ){
        pTS->aaOutput[iOut] = aMerge;
        pTS->anOutput[iOut] = nMerge;
      }
    }
  }

  return SQLITE_OK;
}




static int fts3DeferredTermSelect(
  Fts3DeferredToken *pToken,      /* Phrase token */
  int isTermPos,                  /* True to include positions */
  int *pnOut,                     /* OUT: Size of list */
  char **ppOut                    /* OUT: Body of list */
){


  char *aSource;
  int nSource;

  aSource = sqlite3Fts3DeferredDoclist(pToken, &nSource);
  if( !aSource ){
    *pnOut = 0;
    *ppOut = 0;
  }else if( isTermPos ){
    *ppOut = sqlite3_malloc(nSource);

    if( !*ppOut ) return SQLITE_NOMEM;
    memcpy(*ppOut, aSource, nSource);
    *pnOut = nSource;
  }else{
    sqlite3_int64 docid;
    *pnOut = sqlite3Fts3GetVarint(aSource, &docid);
    *ppOut = sqlite3_malloc(*pnOut);
    if( !*ppOut ) return SQLITE_NOMEM;
    sqlite3Fts3PutVarint(*ppOut, docid);
  }



  return SQLITE_OK;
}

SQLITE_PRIVATE int sqlite3Fts3SegReaderCursor(
  Fts3Table *p,                   /* FTS3 table handle */

  int iLevel,                     /* Level of segments to scan */
  const char *zTerm,              /* Term to query for */
  int nTerm,                      /* Size of zTerm in bytes */
  int isPrefix,                   /* True for a prefix search */
  int isScan,                     /* True to scan from zTerm to EOF */
  Fts3SegReaderCursor *pCsr       /* Cursor object to populate */
){
  int rc = SQLITE_OK;
  int rc2;
  int iAge = 0;
  sqlite3_stmt *pStmt = 0;
  Fts3SegReader *pPending = 0;

  assert( iLevel==FTS3_SEGCURSOR_ALL 
      ||  iLevel==FTS3_SEGCURSOR_PENDING 
      ||  iLevel>=0
  );
  assert( FTS3_SEGCURSOR_PENDING<0 );
  assert( FTS3_SEGCURSOR_ALL<0 );
  assert( iLevel==FTS3_SEGCURSOR_ALL || (zTerm==0 && isPrefix==1) );
  assert( isPrefix==0 || isScan==0 );


  memset(pCsr, 0, sizeof(Fts3SegReaderCursor));

  /* If iLevel is less than 0, include a seg-reader for the pending-terms. */
  assert( isScan==0 || fts3HashCount(&p->pendingTerms)==0 );





  if( iLevel<0 && isScan==0 ){

    rc = sqlite3Fts3SegReaderPending(p, zTerm, nTerm, isPrefix, &pPending);
    if( rc==SQLITE_OK && pPending ){
      int nByte = (sizeof(Fts3SegReader *) * 16);
      pCsr->apSegment = (Fts3SegReader **)sqlite3_malloc(nByte);
      if( pCsr->apSegment==0 ){
        rc = SQLITE_NOMEM;
      }else{
        pCsr->apSegment[0] = pPending;
        pCsr->nSegment = 1;
        pPending = 0;
      }

    }
  }

  if( iLevel!=FTS3_SEGCURSOR_PENDING ){
    if( rc==SQLITE_OK ){
      rc = sqlite3Fts3AllSegdirs(p, iLevel, &pStmt);
    }

    while( rc==SQLITE_OK && SQLITE_ROW==(rc = sqlite3_step(pStmt)) ){


      /* Read the values returned by the SELECT into local variables. */
      sqlite3_int64 iStartBlock = sqlite3_column_int64(pStmt, 1);
      sqlite3_int64 iLeavesEndBlock = sqlite3_column_int64(pStmt, 2);
      sqlite3_int64 iEndBlock = sqlite3_column_int64(pStmt, 3);
      int nRoot = sqlite3_column_bytes(pStmt, 4);
      char const *zRoot = sqlite3_column_blob(pStmt, 4);

      /* If nSegment is a multiple of 16 the array needs to be extended. */
      if( (pCsr->nSegment%16)==0 ){
        Fts3SegReader **apNew;
        int nByte = (pCsr->nSegment + 16)*sizeof(Fts3SegReader*);
        apNew = (Fts3SegReader **)sqlite3_realloc(pCsr->apSegment, nByte);
        if( !apNew ){
          rc = SQLITE_NOMEM;
          goto finished;
        }
        pCsr->apSegment = apNew;
      }

      /* If zTerm is not NULL, and this segment is not stored entirely on its
      ** root node, the range of leaves scanned can be reduced. Do this. */
      if( iStartBlock && zTerm ){
        sqlite3_int64 *pi = (isPrefix ? &iLeavesEndBlock : 0);
        rc = fts3SelectLeaf(p, zTerm, nTerm, zRoot, nRoot, &iStartBlock, pi);
        if( rc!=SQLITE_OK ) goto finished;
        if( isPrefix==0 && isScan==0 ) iLeavesEndBlock = iStartBlock;
      }
 
      rc = sqlite3Fts3SegReaderNew(iAge, iStartBlock, iLeavesEndBlock,
          iEndBlock, zRoot, nRoot, &pCsr->apSegment[pCsr->nSegment]
      );
      if( rc!=SQLITE_OK ) goto finished;
      pCsr->nSegment++;
      iAge++;
    }
  }

 finished:
  rc2 = sqlite3_reset(pStmt);
  if( rc==SQLITE_DONE ) rc = rc2;
  sqlite3Fts3SegReaderFree(pPending);

  return rc;
}






























static int fts3TermSegReaderCursor(















  Fts3Cursor *pCsr,               /* Virtual table cursor handle */
  const char *zTerm,              /* Term to query for */
  int nTerm,                      /* Size of zTerm in bytes */
  int isPrefix,                   /* True for a prefix search */
  Fts3SegReaderCursor **ppSegcsr  /* OUT: Allocated seg-reader cursor */
){
  Fts3SegReaderCursor *pSegcsr;   /* Object to allocate and return */
  int rc = SQLITE_NOMEM;          /* Return code */

  pSegcsr = sqlite3_malloc(sizeof(Fts3SegReaderCursor));
  if( pSegcsr ){
    Fts3Table *p = (Fts3Table *)pCsr->base.pVtab;
    int i;

    int nCost = 0;





    rc = sqlite3Fts3SegReaderCursor(
        p, FTS3_SEGCURSOR_ALL, zTerm, nTerm, isPrefix, 0, pSegcsr);

  








    for(i=0; rc==SQLITE_OK && i<pSegcsr->nSegment; i++){







      rc = sqlite3Fts3SegReaderCost(pCsr, pSegcsr->apSegment[i], &nCost);



    }
    pSegcsr->nCost = nCost;
  }

  *ppSegcsr = pSegcsr;
  return rc;
}

static void fts3SegReaderCursorFree(Fts3SegReaderCursor *pSegcsr){
  sqlite3Fts3SegReaderFinish(pSegcsr);
  sqlite3_free(pSegcsr);
}

/*
** This function retreives the doclist for the specified term (or term
** prefix) from the database. 
................................................................................
  Fts3PhraseToken *pTok,          /* Token to query for */
  int iColumn,                    /* Column to query (or -ve for all columns) */
  int isReqPos,                   /* True to include position lists in output */
  int *pnOut,                     /* OUT: Size of buffer at *ppOut */
  char **ppOut                    /* OUT: Malloced result buffer */
){
  int rc;                         /* Return code */
  Fts3SegReaderCursor *pSegcsr;   /* Seg-reader cursor for this term */
  TermSelect tsc;                 /* Context object for fts3TermSelectCb() */
  Fts3SegFilter filter;           /* Segment term filter configuration */

  pSegcsr = pTok->pSegcsr;
  memset(&tsc, 0, sizeof(TermSelect));
  tsc.isReqPos = isReqPos;

................................................................................
  ){
    rc = fts3TermSelectCb(p, (void *)&tsc, 
        pSegcsr->zTerm, pSegcsr->nTerm, pSegcsr->aDoclist, pSegcsr->nDoclist
    );
  }

  if( rc==SQLITE_OK ){
    rc = fts3TermSelectMerge(&tsc);
  }
  if( rc==SQLITE_OK ){
    *ppOut = tsc.aaOutput[0];
    *pnOut = tsc.anOutput[0];
  }else{
    int i;
    for(i=0; i<SizeofArray(tsc.aaOutput); i++){
................................................................................
      }
    }
  }

  return nDoc;
}

/*
** Call sqlite3Fts3DeferToken() for each token in the expression pExpr.
*/
static int fts3DeferExpression(Fts3Cursor *pCsr, Fts3Expr *pExpr){
  int rc = SQLITE_OK;
  if( pExpr ){
    rc = fts3DeferExpression(pCsr, pExpr->pLeft);
    if( rc==SQLITE_OK ){
      rc = fts3DeferExpression(pCsr, pExpr->pRight);
    }
    if( pExpr->eType==FTSQUERY_PHRASE ){
      int iCol = pExpr->pPhrase->iColumn;
      int i;
      for(i=0; rc==SQLITE_OK && i<pExpr->pPhrase->nToken; i++){
        Fts3PhraseToken *pToken = &pExpr->pPhrase->aToken[i];
        if( pToken->pDeferred==0 ){
          rc = sqlite3Fts3DeferToken(pCsr, pToken, iCol);
        }
      }
    }
  }
  return rc;
}

/*
** This function removes the position information from a doclist. When
** called, buffer aList (size *pnList bytes) contains a doclist that includes
** position information. This function removes the position information so
** that aList contains only docids, and adjusts *pnList to reflect the new
** (possibly reduced) size of the doclist.
*/
static void fts3DoclistStripPositions(
  char *aList,                    /* IN/OUT: Buffer containing doclist */
  int *pnList                     /* IN/OUT: Size of doclist in bytes */
){
  if( aList ){
    char *aEnd = &aList[*pnList]; /* Pointer to one byte after EOF */
    char *p = aList;              /* Input cursor */
    char *pOut = aList;           /* Output cursor */
  
    while( p<aEnd ){
      sqlite3_int64 delta;
      p += sqlite3Fts3GetVarint(p, &delta);
      fts3PoslistCopy(0, &p);
      pOut += sqlite3Fts3PutVarint(pOut, delta);
    }

    *pnList = (int)(pOut - aList);
  }
}

/* 
** Return a DocList corresponding to the phrase *pPhrase.
**
** If this function returns SQLITE_OK, but *pnOut is set to a negative value,
** then no tokens in the phrase were looked up in the full-text index. This
** is only possible when this function is called from within xFilter(). The
** caller should assume that all documents match the phrase. The actual
** filtering will take place in xNext().
*/
static int fts3PhraseSelect(
  Fts3Cursor *pCsr,               /* Virtual table cursor handle */
  Fts3Phrase *pPhrase,            /* Phrase to return a doclist for */
  int isReqPos,                   /* True if output should contain positions */
  char **paOut,                   /* OUT: Pointer to malloc'd result buffer */
  int *pnOut                      /* OUT: Size of buffer at *paOut */
){
  char *pOut = 0;
  int nOut = 0;
  int rc = SQLITE_OK;
  int ii;
  int iCol = pPhrase->iColumn;
  int isTermPos = (pPhrase->nToken>1 || isReqPos);
  Fts3Table *p = (Fts3Table *)pCsr->base.pVtab;
  int isFirst = 1;

  int iPrevTok = 0;
  int nDoc = 0;

  /* If this is an xFilter() evaluation, create a segment-reader for each
  ** phrase token. Or, if this is an xNext() or snippet/offsets/matchinfo
  ** evaluation, only create segment-readers if there are no Fts3DeferredToken
  ** objects attached to the phrase-tokens.
  */
  for(ii=0; ii<pPhrase->nToken; ii++){
    Fts3PhraseToken *pTok = &pPhrase->aToken[ii];
    if( pTok->pSegcsr==0 ){
      if( (pCsr->eEvalmode==FTS3_EVAL_FILTER)
       || (pCsr->eEvalmode==FTS3_EVAL_NEXT && pCsr->pDeferred==0) 
       || (pCsr->eEvalmode==FTS3_EVAL_MATCHINFO && pTok->bFulltext) 
      ){
        rc = fts3TermSegReaderCursor(
            pCsr, pTok->z, pTok->n, pTok->isPrefix, &pTok->pSegcsr
        );
        if( rc!=SQLITE_OK ) return rc;
      }
    }
  }

  for(ii=0; ii<pPhrase->nToken; ii++){
    Fts3PhraseToken *pTok;        /* Token to find doclist for */
    int iTok = 0;                 /* The token being queried this iteration */
    char *pList = 0;              /* Pointer to token doclist */
    int nList = 0;                /* Size of buffer at pList */

    /* Select a token to process. If this is an xFilter() call, then tokens 
    ** are processed in order from least to most costly. Otherwise, tokens 
    ** are processed in the order in which they occur in the phrase.
    */
    if( pCsr->eEvalmode==FTS3_EVAL_MATCHINFO ){
      assert( isReqPos );
      iTok = ii;
      pTok = &pPhrase->aToken[iTok];
      if( pTok->bFulltext==0 ) continue;
    }else if( pCsr->eEvalmode==FTS3_EVAL_NEXT || isReqPos ){
      iTok = ii;
      pTok = &pPhrase->aToken[iTok];
    }else{
      int nMinCost = 0x7FFFFFFF;
      int jj;

      /* Find the remaining token with the lowest cost. */
      for(jj=0; jj<pPhrase->nToken; jj++){
        Fts3SegReaderCursor *pSegcsr = pPhrase->aToken[jj].pSegcsr;
        if( pSegcsr && pSegcsr->nCost<nMinCost ){
          iTok = jj;
          nMinCost = pSegcsr->nCost;
        }
      }
      pTok = &pPhrase->aToken[iTok];

      /* This branch is taken if it is determined that loading the doclist
      ** for the next token would require more IO than loading all documents
      ** currently identified by doclist pOut/nOut. No further doclists will
      ** be loaded from the full-text index for this phrase.
      */
      if( nMinCost>nDoc && ii>0 ){
        rc = fts3DeferExpression(pCsr, pCsr->pExpr);
        break;
      }
    }

    if( pCsr->eEvalmode==FTS3_EVAL_NEXT && pTok->pDeferred ){
      rc = fts3DeferredTermSelect(pTok->pDeferred, isTermPos, &nList, &pList);
    }else{
      if( pTok->pSegcsr ){
        rc = fts3TermSelect(p, pTok, iCol, isTermPos, &nList, &pList);
      }
      pTok->bFulltext = 1;
    }
    assert( rc!=SQLITE_OK || pCsr->eEvalmode || pTok->pSegcsr==0 );
    if( rc!=SQLITE_OK ) break;

    if( isFirst ){
      pOut = pList;
      nOut = nList;
      if( pCsr->eEvalmode==FTS3_EVAL_FILTER && pPhrase->nToken>1 ){
        nDoc = fts3DoclistCountDocids(1, pOut, nOut);
      }
      isFirst = 0;
      iPrevTok = iTok;
    }else{
      /* Merge the new term list and the current output. */
      char *aLeft, *aRight;
      int nLeft, nRight;
      int nDist;
      int mt;

      /* If this is the final token of the phrase, and positions were not
      ** requested by the caller, use MERGE_PHRASE instead of POS_PHRASE.
      ** This drops the position information from the output list.
      */
      mt = MERGE_POS_PHRASE;
      if( ii==pPhrase->nToken-1 && !isReqPos ) mt = MERGE_PHRASE;

      assert( iPrevTok!=iTok );
      if( iPrevTok<iTok ){
        aLeft = pOut;
        nLeft = nOut;
        aRight = pList;
        nRight = nList;
        nDist = iTok-iPrevTok;
        iPrevTok = iTok;
      }else{
        aRight = pOut;
        nRight = nOut;
        aLeft = pList;
        nLeft = nList;
        nDist = iPrevTok-iTok;
      }
      pOut = aRight;
      fts3DoclistMerge(
          mt, nDist, 0, pOut, &nOut, aLeft, nLeft, aRight, nRight, &nDoc
      );
      sqlite3_free(aLeft);
    }
    assert( nOut==0 || pOut!=0 );
  }

  if( rc==SQLITE_OK ){
    if( ii!=pPhrase->nToken ){
      assert( pCsr->eEvalmode==FTS3_EVAL_FILTER && isReqPos==0 );
      fts3DoclistStripPositions(pOut, &nOut);
    }
    *paOut = pOut;
    *pnOut = nOut;
  }else{
    sqlite3_free(pOut);
  }
  return rc;
}

/*
** This function merges two doclists according to the requirements of a
** NEAR operator.
**
** Both input doclists must include position information. The output doclist 
** includes position information if the first argument to this function
** is MERGE_POS_NEAR, or does not if it is MERGE_NEAR.
*/
static int fts3NearMerge(
  int mergetype,                  /* MERGE_POS_NEAR or MERGE_NEAR */
  int nNear,                      /* Parameter to NEAR operator */
  int nTokenLeft,                 /* Number of tokens in LHS phrase arg */
  char *aLeft,                    /* Doclist for LHS (incl. positions) */
  int nLeft,                      /* Size of LHS doclist in bytes */
  int nTokenRight,                /* As nTokenLeft */
  char *aRight,                   /* As aLeft */
  int nRight,                     /* As nRight */
  char **paOut,                   /* OUT: Results of merge (malloced) */
  int *pnOut                      /* OUT: Sized of output buffer */
){
  char *aOut;                     /* Buffer to write output doclist to */
  int rc;                         /* Return code */

  assert( mergetype==MERGE_POS_NEAR || MERGE_NEAR );

  aOut = sqlite3_malloc(nLeft+nRight+1);
  if( aOut==0 ){
    rc = SQLITE_NOMEM;
  }else{
    rc = fts3DoclistMerge(mergetype, nNear+nTokenRight, nNear+nTokenLeft, 
      aOut, pnOut, aLeft, nLeft, aRight, nRight, 0
    );
    if( rc!=SQLITE_OK ){
      sqlite3_free(aOut);
      aOut = 0;
    }
  }

  *paOut = aOut;
  return rc;
}

/*
** This function is used as part of the processing for the snippet() and
** offsets() functions.
**
** Both pLeft and pRight are expression nodes of type FTSQUERY_PHRASE. Both
** have their respective doclists (including position information) loaded
** in Fts3Expr.aDoclist/nDoclist. This function removes all entries from
** each doclist that are not within nNear tokens of a corresponding entry
** in the other doclist.
*/
SQLITE_PRIVATE int sqlite3Fts3ExprNearTrim(Fts3Expr *pLeft, Fts3Expr *pRight, int nNear){
  int rc;                         /* Return code */

  assert( pLeft->eType==FTSQUERY_PHRASE );
  assert( pRight->eType==FTSQUERY_PHRASE );
  assert( pLeft->isLoaded && pRight->isLoaded );

  if( pLeft->aDoclist==0 || pRight->aDoclist==0 ){
    sqlite3_free(pLeft->aDoclist);
    sqlite3_free(pRight->aDoclist);
    pRight->aDoclist = 0;
    pLeft->aDoclist = 0;
    rc = SQLITE_OK;
  }else{
    char *aOut;                   /* Buffer in which to assemble new doclist */
    int nOut;                     /* Size of buffer aOut in bytes */

    rc = fts3NearMerge(MERGE_POS_NEAR, nNear, 
        pLeft->pPhrase->nToken, pLeft->aDoclist, pLeft->nDoclist,
        pRight->pPhrase->nToken, pRight->aDoclist, pRight->nDoclist,
        &aOut, &nOut
    );
    if( rc!=SQLITE_OK ) return rc;
    sqlite3_free(pRight->aDoclist);
    pRight->aDoclist = aOut;
    pRight->nDoclist = nOut;

    rc = fts3NearMerge(MERGE_POS_NEAR, nNear, 
        pRight->pPhrase->nToken, pRight->aDoclist, pRight->nDoclist,
        pLeft->pPhrase->nToken, pLeft->aDoclist, pLeft->nDoclist,
        &aOut, &nOut
    );
    sqlite3_free(pLeft->aDoclist);
    pLeft->aDoclist = aOut;
    pLeft->nDoclist = nOut;
  }
  return rc;
}


/*
** Allocate an Fts3SegReaderArray for each token in the expression pExpr. 
** The allocated objects are stored in the Fts3PhraseToken.pArray member
** variables of each token structure.
*/
static int fts3ExprAllocateSegReaders(
  Fts3Cursor *pCsr,               /* FTS3 table */
  Fts3Expr *pExpr,                /* Expression to create seg-readers for */
  int *pnExpr                     /* OUT: Number of AND'd expressions */
){
  int rc = SQLITE_OK;             /* Return code */

  assert( pCsr->eEvalmode==FTS3_EVAL_FILTER );
  if( pnExpr && pExpr->eType!=FTSQUERY_AND ){
    (*pnExpr)++;
    pnExpr = 0;
  }

  if( pExpr->eType==FTSQUERY_PHRASE ){
    Fts3Phrase *pPhrase = pExpr->pPhrase;
    int ii;

    for(ii=0; rc==SQLITE_OK && ii<pPhrase->nToken; ii++){
      Fts3PhraseToken *pTok = &pPhrase->aToken[ii];
      if( pTok->pSegcsr==0 ){
        rc = fts3TermSegReaderCursor(
            pCsr, pTok->z, pTok->n, pTok->isPrefix, &pTok->pSegcsr
        );
      }
    }
  }else{ 
    rc = fts3ExprAllocateSegReaders(pCsr, pExpr->pLeft, pnExpr);
    if( rc==SQLITE_OK ){
      rc = fts3ExprAllocateSegReaders(pCsr, pExpr->pRight, pnExpr);
    }
  }
  return rc;
}

/*
** Free the Fts3SegReaderArray objects associated with each token in the
** expression pExpr. In other words, this function frees the resources
** allocated by fts3ExprAllocateSegReaders().
*/
static void fts3ExprFreeSegReaders(Fts3Expr *pExpr){
  if( pExpr ){
    Fts3Phrase *pPhrase = pExpr->pPhrase;
    if( pPhrase ){
      int kk;
      for(kk=0; kk<pPhrase->nToken; kk++){
        fts3SegReaderCursorFree(pPhrase->aToken[kk].pSegcsr);
        pPhrase->aToken[kk].pSegcsr = 0;
      }
    }
    fts3ExprFreeSegReaders(pExpr->pLeft);
    fts3ExprFreeSegReaders(pExpr->pRight);
  }
}

/*
** Return the sum of the costs of all tokens in the expression pExpr. This
** function must be called after Fts3SegReaderArrays have been allocated
** for all tokens using fts3ExprAllocateSegReaders().
*/
static int fts3ExprCost(Fts3Expr *pExpr){
  int nCost;                      /* Return value */
  if( pExpr->eType==FTSQUERY_PHRASE ){
    Fts3Phrase *pPhrase = pExpr->pPhrase;
    int ii;
    nCost = 0;
    for(ii=0; ii<pPhrase->nToken; ii++){
      Fts3SegReaderCursor *pSegcsr = pPhrase->aToken[ii].pSegcsr;
      if( pSegcsr ) nCost += pSegcsr->nCost;
    }
  }else{
    nCost = fts3ExprCost(pExpr->pLeft) + fts3ExprCost(pExpr->pRight);
  }
  return nCost;
}

/*
** The following is a helper function (and type) for fts3EvalExpr(). It
** must be called after Fts3SegReaders have been allocated for every token
** in the expression. See the context it is called from in fts3EvalExpr()
** for further explanation.
*/
typedef struct ExprAndCost ExprAndCost;
struct ExprAndCost {
  Fts3Expr *pExpr;
  int nCost;
};
static void fts3ExprAssignCosts(
  Fts3Expr *pExpr,                /* Expression to create seg-readers for */
  ExprAndCost **ppExprCost        /* OUT: Write to *ppExprCost */
){
  if( pExpr->eType==FTSQUERY_AND ){
    fts3ExprAssignCosts(pExpr->pLeft, ppExprCost);
    fts3ExprAssignCosts(pExpr->pRight, ppExprCost);
  }else{
    (*ppExprCost)->pExpr = pExpr;
    (*ppExprCost)->nCost = fts3ExprCost(pExpr);
    (*ppExprCost)++;
  }
}

/*
** Evaluate the full-text expression pExpr against FTS3 table pTab. Store
** the resulting doclist in *paOut and *pnOut. This routine mallocs for
** the space needed to store the output. The caller is responsible for
** freeing the space when it has finished.
**
** This function is called in two distinct contexts:
**
**   * From within the virtual table xFilter() method. In this case, the
**     output doclist contains entries for all rows in the table, based on
**     data read from the full-text index.
**
**     In this case, if the query expression contains one or more tokens that 
**     are very common, then the returned doclist may contain a superset of 
**     the documents that actually match the expression.
**
**   * From within the virtual table xNext() method. This call is only made
**     if the call from within xFilter() found that there were very common 
**     tokens in the query expression and did return a superset of the 
**     matching documents. In this case the returned doclist contains only
**     entries that correspond to the current row of the table. Instead of
**     reading the data for each token from the full-text index, the data is
**     already available in-memory in the Fts3PhraseToken.pDeferred structures.
**     See fts3EvalDeferred() for how it gets there.
**
** In the first case above, Fts3Cursor.doDeferred==0. In the second (if it is
** required) Fts3Cursor.doDeferred==1.
**
** If the SQLite invokes the snippet(), offsets() or matchinfo() function
** as part of a SELECT on an FTS3 table, this function is called on each
** individual phrase expression in the query. If there were very common tokens
** found in the xFilter() call, then this function is called once for phrase
** for each row visited, and the returned doclist contains entries for the
** current row only. Otherwise, if there were no very common tokens, then this
** function is called once only for each phrase in the query and the returned
** doclist contains entries for all rows of the table.
**
** Fts3Cursor.doDeferred==1 when this function is called on phrases as a
** result of a snippet(), offsets() or matchinfo() invocation.
*/
static int fts3EvalExpr(
  Fts3Cursor *p,                  /* Virtual table cursor handle */
  Fts3Expr *pExpr,                /* Parsed fts3 expression */
  char **paOut,                   /* OUT: Pointer to malloc'd result buffer */
  int *pnOut,                     /* OUT: Size of buffer at *paOut */
  int isReqPos                    /* Require positions in output buffer */
){
  int rc = SQLITE_OK;             /* Return code */

  /* Zero the output parameters. */
  *paOut = 0;
  *pnOut = 0;

  if( pExpr ){
    assert( pExpr->eType==FTSQUERY_NEAR   || pExpr->eType==FTSQUERY_OR     
         || pExpr->eType==FTSQUERY_AND    || pExpr->eType==FTSQUERY_NOT
         || pExpr->eType==FTSQUERY_PHRASE
    );
    assert( pExpr->eType==FTSQUERY_PHRASE || isReqPos==0 );

    if( pExpr->eType==FTSQUERY_PHRASE ){
      rc = fts3PhraseSelect(p, pExpr->pPhrase,
          isReqPos || (pExpr->pParent && pExpr->pParent->eType==FTSQUERY_NEAR),
          paOut, pnOut
      );
      fts3ExprFreeSegReaders(pExpr);
    }else if( p->eEvalmode==FTS3_EVAL_FILTER && pExpr->eType==FTSQUERY_AND ){
      ExprAndCost *aExpr = 0;     /* Array of AND'd expressions and costs */
      int nExpr = 0;              /* Size of aExpr[] */
      char *aRet = 0;             /* Doclist to return to caller */
      int nRet = 0;               /* Length of aRet[] in bytes */
      int nDoc = 0x7FFFFFFF;

      assert( !isReqPos );

      rc = fts3ExprAllocateSegReaders(p, pExpr, &nExpr);
      if( rc==SQLITE_OK ){
        assert( nExpr>1 );
        aExpr = sqlite3_malloc(sizeof(ExprAndCost) * nExpr);
        if( !aExpr ) rc = SQLITE_NOMEM;
      }
      if( rc==SQLITE_OK ){
        int ii;                   /* Used to iterate through expressions */

        fts3ExprAssignCosts(pExpr, &aExpr);
        aExpr -= nExpr;
        for(ii=0; ii<nExpr; ii++){
          char *aNew;
          int nNew;
          int jj;
          ExprAndCost *pBest = 0;
  
          for(jj=0; jj<nExpr; jj++){
            ExprAndCost *pCand = &aExpr[jj];
            if( pCand->pExpr && (pBest==0 || pCand->nCost<pBest->nCost) ){
              pBest = pCand;
            }
          }
  
          if( pBest->nCost>nDoc ){
            rc = fts3DeferExpression(p, p->pExpr);
            break;
          }else{
            rc = fts3EvalExpr(p, pBest->pExpr, &aNew, &nNew, 0);
            if( rc!=SQLITE_OK ) break;
            pBest->pExpr = 0;
            if( ii==0 ){
              aRet = aNew;
              nRet = nNew;
              nDoc = fts3DoclistCountDocids(0, aRet, nRet);
            }else{
              fts3DoclistMerge(
                  MERGE_AND, 0, 0, aRet, &nRet, aRet, nRet, aNew, nNew, &nDoc
              );
              sqlite3_free(aNew);
            }
          }
        }
      }

      if( rc==SQLITE_OK ){
        *paOut = aRet;
        *pnOut = nRet;
      }else{
        assert( *paOut==0 );
        sqlite3_free(aRet);
      }
      sqlite3_free(aExpr);
      fts3ExprFreeSegReaders(pExpr);

    }else{
      char *aLeft;
      char *aRight;
      int nLeft;
      int nRight;

      assert( pExpr->eType==FTSQUERY_NEAR 
           || pExpr->eType==FTSQUERY_OR
           || pExpr->eType==FTSQUERY_NOT
           || (pExpr->eType==FTSQUERY_AND && p->eEvalmode==FTS3_EVAL_NEXT)
      );

      if( 0==(rc = fts3EvalExpr(p, pExpr->pRight, &aRight, &nRight, isReqPos))
       && 0==(rc = fts3EvalExpr(p, pExpr->pLeft, &aLeft, &nLeft, isReqPos))
      ){
        switch( pExpr->eType ){
          case FTSQUERY_NEAR: {
            Fts3Expr *pLeft;
            Fts3Expr *pRight;
            int mergetype = MERGE_NEAR;
            if( pExpr->pParent && pExpr->pParent->eType==FTSQUERY_NEAR ){
              mergetype = MERGE_POS_NEAR;
            }
            pLeft = pExpr->pLeft;
            while( pLeft->eType==FTSQUERY_NEAR ){ 
              pLeft=pLeft->pRight;
            }
            pRight = pExpr->pRight;
            assert( pRight->eType==FTSQUERY_PHRASE );
            assert( pLeft->eType==FTSQUERY_PHRASE );

            rc = fts3NearMerge(mergetype, pExpr->nNear, 
                pLeft->pPhrase->nToken, aLeft, nLeft,
                pRight->pPhrase->nToken, aRight, nRight,
                paOut, pnOut
            );
            sqlite3_free(aLeft);
            break;
          }

          case FTSQUERY_OR: {
            /* Allocate a buffer for the output. The maximum size is the
            ** sum of the sizes of the two input buffers. The +1 term is
            ** so that a buffer of zero bytes is never allocated - this can
            ** cause fts3DoclistMerge() to incorrectly return SQLITE_NOMEM.
            */
            char *aBuffer = sqlite3_malloc(nRight+nLeft+1);
            rc = fts3DoclistMerge(MERGE_OR, 0, 0, aBuffer, pnOut,
                aLeft, nLeft, aRight, nRight, 0
            );
            *paOut = aBuffer;
            sqlite3_free(aLeft);
            break;
          }

          default: {
            assert( FTSQUERY_NOT==MERGE_NOT && FTSQUERY_AND==MERGE_AND );
            fts3DoclistMerge(pExpr->eType, 0, 0, aLeft, pnOut,
                aLeft, nLeft, aRight, nRight, 0
            );
            *paOut = aLeft;
            break;
          }
        }
      }
      sqlite3_free(aRight);
    }
  }

  assert( rc==SQLITE_OK || *paOut==0 );
  return rc;
}

/*
** This function is called from within xNext() for each row visited by
** an FTS3 query. If evaluating the FTS3 query expression within xFilter()
** was able to determine the exact set of matching rows, this function sets
** *pbRes to true and returns SQLITE_IO immediately.
**
** Otherwise, if evaluating the query expression within xFilter() returned a
** superset of the matching documents instead of an exact set (this happens
** when the query includes very common tokens and it is deemed too expensive to
** load their doclists from disk), this function tests if the current row
** really does match the FTS3 query.
**
** If an error occurs, an SQLite error code is returned. Otherwise, SQLITE_OK
** is returned and *pbRes is set to true if the current row matches the
** FTS3 query (and should be included in the results returned to SQLite), or
** false otherwise.
*/
static int fts3EvalDeferred(
  Fts3Cursor *pCsr,               /* FTS3 cursor pointing at row to test */
  int *pbRes                      /* OUT: Set to true if row is a match */
){
  int rc = SQLITE_OK;
  if( pCsr->pDeferred==0 ){
    *pbRes = 1;
  }else{
    rc = fts3CursorSeek(0, pCsr);
    if( rc==SQLITE_OK ){
      sqlite3Fts3FreeDeferredDoclists(pCsr);
      rc = sqlite3Fts3CacheDeferredDoclists(pCsr);
    }
    if( rc==SQLITE_OK ){
      char *a = 0;
      int n = 0;
      rc = fts3EvalExpr(pCsr, pCsr->pExpr, &a, &n, 0);
      assert( n>=0 );
      *pbRes = (n>0);
      sqlite3_free(a);
    }
  }
  return rc;
}

/*
** Advance the cursor to the next row in the %_content table that
** matches the search criteria.  For a MATCH search, this will be
** the next row that matches. For a full-table scan, this will be
** simply the next row in the %_content table.  For a docid lookup,
** this routine simply sets the EOF flag.
**
** Return SQLITE_OK if nothing goes wrong.  SQLITE_OK is returned
** even if we reach end-of-file.  The fts3EofMethod() will be called
** subsequently to determine whether or not an EOF was hit.
*/
static int fts3NextMethod(sqlite3_vtab_cursor *pCursor){
  int res;
  int rc = SQLITE_OK;             /* Return code */
  Fts3Cursor *pCsr = (Fts3Cursor *)pCursor;

  pCsr->eEvalmode = FTS3_EVAL_NEXT;
  do {
    if( pCsr->aDoclist==0 ){

      if( SQLITE_ROW!=sqlite3_step(pCsr->pStmt) ){
        pCsr->isEof = 1;
        rc = sqlite3_reset(pCsr->pStmt);
        break;
      }
      pCsr->iPrevId = sqlite3_column_int64(pCsr->pStmt, 0);
    }else{
      if( pCsr->desc==0 ){
        if( pCsr->pNextId>=&pCsr->aDoclist[pCsr->nDoclist] ){
          pCsr->isEof = 1;
          break;


        }
        fts3GetDeltaVarint(&pCsr->pNextId, &pCsr->iPrevId);
      }else{
        fts3GetReverseDeltaVarint(&pCsr->pNextId,pCsr->aDoclist,&pCsr->iPrevId);
        if( pCsr->pNextId<=pCsr->aDoclist ){
          pCsr->isEof = 1;
          break;

        }
      }
      sqlite3_reset(pCsr->pStmt);
      pCsr->isRequireSeek = 1;
      pCsr->isMatchinfoNeeded = 1;
    }
  }while( SQLITE_OK==(rc = fts3EvalDeferred(pCsr, &res)) && res==0 );


  return rc;
}

/*
** This is the xFilter interface for the virtual table.  See
** the virtual table xFilter method documentation for additional
** information.
................................................................................
static int fts3FilterMethod(
  sqlite3_vtab_cursor *pCursor,   /* The cursor used for this query */
  int idxNum,                     /* Strategy index */
  const char *idxStr,             /* Unused */
  int nVal,                       /* Number of elements in apVal */
  sqlite3_value **apVal           /* Arguments for the indexing scheme */
){
  const char *azSql[] = {
    "SELECT %s FROM %Q.'%q_content' AS x WHERE docid = ?",   /* non-full-scan */
    "SELECT %s FROM %Q.'%q_content' AS x ORDER BY docid %s", /* full-scan */
  };
  int rc;                         /* Return code */
  char *zSql;                     /* SQL statement used to access %_content */
  Fts3Table *p = (Fts3Table *)pCursor->pVtab;
  Fts3Cursor *pCsr = (Fts3Cursor *)pCursor;

  UNUSED_PARAMETER(idxStr);
  UNUSED_PARAMETER(nVal);

................................................................................

  /* In case the cursor has been used before, clear it now. */
  sqlite3_finalize(pCsr->pStmt);
  sqlite3_free(pCsr->aDoclist);
  sqlite3Fts3ExprFree(pCsr->pExpr);
  memset(&pCursor[1], 0, sizeof(Fts3Cursor)-sizeof(sqlite3_vtab_cursor));








  if( idxNum!=FTS3_DOCID_SEARCH && idxNum!=FTS3_FULLSCAN_SEARCH ){
    int iCol = idxNum-FTS3_FULLTEXT_SEARCH;
    const char *zQuery = (const char *)sqlite3_value_text(apVal[0]);

    if( zQuery==0 && sqlite3_value_type(apVal[0])!=SQLITE_NULL ){
      return SQLITE_NOMEM;
    }

    rc = sqlite3Fts3ExprParse(p->pTokenizer, p->azColumn, p->nColumn, 
        iCol, zQuery, -1, &pCsr->pExpr
    );
    if( rc!=SQLITE_OK ){
      if( rc==SQLITE_ERROR ){
        p->base.zErrMsg = sqlite3_mprintf("malformed MATCH expression: [%s]",
                                          zQuery);
      }
      return rc;
    }

    rc = sqlite3Fts3ReadLock(p);
    if( rc!=SQLITE_OK ) return rc;

    rc = fts3EvalExpr(pCsr, pCsr->pExpr, &pCsr->aDoclist, &pCsr->nDoclist, 0);

    sqlite3Fts3SegmentsClose(p);
    if( rc!=SQLITE_OK ) return rc;
    pCsr->pNextId = pCsr->aDoclist;
    pCsr->iPrevId = 0;
  }

  /* Compile a SELECT statement for this cursor. For a full-table-scan, the
  ** statement loops through all rows of the %_content table. For a
  ** full-text query or docid lookup, the statement retrieves a single
  ** row by docid.
  */
  zSql = (char *)azSql[idxNum==FTS3_FULLSCAN_SEARCH];
  zSql = sqlite3_mprintf(

      zSql, p->zReadExprlist, p->zDb, p->zName, (idxStr ? idxStr : "ASC")
  );
  if( !zSql ){
    rc = SQLITE_NOMEM;
  }else{




    rc = sqlite3_prepare_v2(p->db, zSql, -1, &pCsr->pStmt, 0);
    sqlite3_free(zSql);

  }
  if( rc==SQLITE_OK && idxNum==FTS3_DOCID_SEARCH ){
    rc = sqlite3_bind_value(pCsr->pStmt, 1, apVal[0]);
  }
  pCsr->eSearch = (i16)idxNum;

  assert( pCsr->desc==0 );
  if( rc!=SQLITE_OK ) return rc;
  if( rc==SQLITE_OK && pCsr->nDoclist>0 && idxStr && idxStr[0]=='D' ){
    sqlite3_int64 iDocid = 0;
    char *csr = pCsr->aDoclist;
    while( csr<&pCsr->aDoclist[pCsr->nDoclist] ){
      fts3GetDeltaVarint(&csr, &iDocid);
    }
    pCsr->pNextId = csr;
    pCsr->iPrevId = iDocid;
    pCsr->desc = 1;
    pCsr->isRequireSeek = 1;
    pCsr->isMatchinfoNeeded = 1;
    pCsr->eEvalmode = FTS3_EVAL_NEXT;
    return SQLITE_OK;
  }
  return fts3NextMethod(pCursor);
}

/* 
** This is the xEof method of the virtual table. SQLite calls this 
** routine to find out if it has reached the end of a result set.
*/
................................................................................
** This is the xRowid method. The SQLite core calls this routine to
** retrieve the rowid for the current row of the result set. fts3
** exposes %_content.docid as the rowid for the virtual table. The
** rowid should be written to *pRowid.
*/
static int fts3RowidMethod(sqlite3_vtab_cursor *pCursor, sqlite_int64 *pRowid){
  Fts3Cursor *pCsr = (Fts3Cursor *) pCursor;
  if( pCsr->aDoclist ){
    *pRowid = pCsr->iPrevId;
  }else{
    /* This branch runs if the query is implemented using a full-table scan
    ** (not using the full-text index). In this case grab the rowid from the
    ** SELECT statement.
    */
    assert( pCsr->isRequireSeek==0 );
    *pRowid = sqlite3_column_int64(pCsr->pStmt, 0);
  }
  return SQLITE_OK;
}

/* 
** This is the xColumn method, called by SQLite to request a value from
** the row that the supplied cursor currently points to.
*/
static int fts3ColumnMethod(
  sqlite3_vtab_cursor *pCursor,   /* Cursor to retrieve value from */
  sqlite3_context *pContext,      /* Context for sqlite3_result_xxx() calls */
  int iCol                        /* Index of column to read value from */
){
  int rc;                         /* Return Code */
  Fts3Cursor *pCsr = (Fts3Cursor *) pCursor;
  Fts3Table *p = (Fts3Table *)pCursor->pVtab;

  /* The column value supplied by SQLite must be in range. */
  assert( iCol>=0 && iCol<=p->nColumn+1 );

  if( iCol==p->nColumn+1 ){
    /* This call is a request for the "docid" column. Since "docid" is an 
    ** alias for "rowid", use the xRowid() method to obtain the value.
    */
    sqlite3_int64 iRowid;
    rc = fts3RowidMethod(pCursor, &iRowid);
    sqlite3_result_int64(pContext, iRowid);
  }else if( iCol==p->nColumn ){
    /* The extra column whose name is the same as the table.
    ** Return a blob which is a pointer to the cursor.
    */
    sqlite3_result_blob(pContext, &pCsr, sizeof(pCsr), SQLITE_TRANSIENT);
    rc = SQLITE_OK;
  }else{
    rc = fts3CursorSeek(0, pCsr);
    if( rc==SQLITE_OK ){
      sqlite3_result_value(pContext, sqlite3_column_value(pCsr->pStmt, iCol+1));
    }
  }


  return rc;
}

/* 
** This function is the implementation of the xUpdate callback used by 
** FTS3 virtual tables. It is invoked by SQLite each time a row is to be
** inserted, updated or deleted.
................................................................................
  return rc;
}

/*
** Implementation of xBegin() method. This is a no-op.
*/
static int fts3BeginMethod(sqlite3_vtab *pVtab){
  UNUSED_PARAMETER(pVtab);
  TESTONLY( Fts3Table *p = (Fts3Table*)pVtab );


  assert( p->nPendingData==0 );
  assert( p->inTransaction!=1 );
  TESTONLY( p->inTransaction = 1 );
  TESTONLY( p->mxSavepoint = -1; );
  return SQLITE_OK;
}

/*
** Implementation of xCommit() method. This is a no-op. The contents of
** the pending-terms hash-table have already been flushed into the database
** by fts3SyncMethod().
*/
static int fts3CommitMethod(sqlite3_vtab *pVtab){
  UNUSED_PARAMETER(pVtab);
  TESTONLY( Fts3Table *p = (Fts3Table*)pVtab );

  assert( p->nPendingData==0 );
  assert( p->inTransaction!=0 );

  TESTONLY( p->inTransaction = 0 );
  TESTONLY( p->mxSavepoint = -1; );
  return SQLITE_OK;
}

/*
** Implementation of xRollback(). Discard the contents of the pending-terms
................................................................................
  Fts3Table *p = (Fts3Table*)pVtab;
  sqlite3Fts3PendingTermsClear(p);
  assert( p->inTransaction!=0 );
  TESTONLY( p->inTransaction = 0 );
  TESTONLY( p->mxSavepoint = -1; );
  return SQLITE_OK;
}

/*
** Load the doclist associated with expression pExpr to pExpr->aDoclist.
** The loaded doclist contains positions as well as the document ids.
** This is used by the matchinfo(), snippet() and offsets() auxillary
** functions.
*/
SQLITE_PRIVATE int sqlite3Fts3ExprLoadDoclist(Fts3Cursor *pCsr, Fts3Expr *pExpr){
  int rc;
  assert( pExpr->eType==FTSQUERY_PHRASE && pExpr->pPhrase );
  assert( pCsr->eEvalmode==FTS3_EVAL_NEXT );
  rc = fts3EvalExpr(pCsr, pExpr, &pExpr->aDoclist, &pExpr->nDoclist, 1);
  return rc;
}

SQLITE_PRIVATE int sqlite3Fts3ExprLoadFtDoclist(
  Fts3Cursor *pCsr, 
  Fts3Expr *pExpr,
  char **paDoclist,
  int *pnDoclist
){
  int rc;
  assert( pCsr->eEvalmode==FTS3_EVAL_NEXT );
  assert( pExpr->eType==FTSQUERY_PHRASE && pExpr->pPhrase );
  pCsr->eEvalmode = FTS3_EVAL_MATCHINFO;
  rc = fts3EvalExpr(pCsr, pExpr, paDoclist, pnDoclist, 1);
  pCsr->eEvalmode = FTS3_EVAL_NEXT;
  return rc;
}


/*
** When called, *ppPoslist must point to the byte immediately following the
** end of a position-list. i.e. ( (*ppPoslist)[-1]==POS_END ). This function
** moves *ppPoslist so that it instead points to the first byte of the
** same position list.
*/
static void fts3ReversePoslist(char *pStart, char **ppPoslist){
  char *p = &(*ppPoslist)[-3];
  char c = p[1];


  while( p>pStart && (*p & 0x80) | c ){ 
    c = *p--; 
  }
  if( p>pStart ){ p = &p[2]; }
  while( *p++&0x80 );
  *ppPoslist = p;
}


/*
** After ExprLoadDoclist() (see above) has been called, this function is
** used to iterate/search through the position lists that make up the doclist
** stored in pExpr->aDoclist.
*/
SQLITE_PRIVATE char *sqlite3Fts3FindPositions(
  Fts3Cursor *pCursor,            /* Associate FTS3 cursor */
  Fts3Expr *pExpr,                /* Access this expressions doclist */
  sqlite3_int64 iDocid,           /* Docid associated with requested pos-list */
  int iCol                        /* Column of requested pos-list */
){
  assert( pExpr->isLoaded );
  if( pExpr->aDoclist ){
    char *pEnd = &pExpr->aDoclist[pExpr->nDoclist];
    char *pCsr;

    if( pExpr->pCurrent==0 ){
      if( pCursor->desc==0 ){
        pExpr->pCurrent = pExpr->aDoclist;
        pExpr->iCurrent = 0;
        fts3GetDeltaVarint(&pExpr->pCurrent, &pExpr->iCurrent);
      }else{
        pCsr = pExpr->aDoclist;
        while( pCsr<pEnd ){
          fts3GetDeltaVarint(&pCsr, &pExpr->iCurrent);
          fts3PoslistCopy(0, &pCsr);
        }
        fts3ReversePoslist(pExpr->aDoclist, &pCsr);
        pExpr->pCurrent = pCsr;
      }
    }
    pCsr = pExpr->pCurrent;
    assert( pCsr );

    while( (pCursor->desc==0 && pCsr<pEnd) 
        || (pCursor->desc && pCsr>pExpr->aDoclist) 
    ){
      if( pCursor->desc==0 && pExpr->iCurrent<iDocid ){
        fts3PoslistCopy(0, &pCsr);
        if( pCsr<pEnd ){
          fts3GetDeltaVarint(&pCsr, &pExpr->iCurrent);
        }
        pExpr->pCurrent = pCsr;
      }else if( pCursor->desc && pExpr->iCurrent>iDocid ){
        fts3GetReverseDeltaVarint(&pCsr, pExpr->aDoclist, &pExpr->iCurrent);
        fts3ReversePoslist(pExpr->aDoclist, &pCsr);
        pExpr->pCurrent = pCsr;
      }else{
        if( pExpr->iCurrent==iDocid ){
          int iThis = 0;
          if( iCol<0 ){
            /* If iCol is negative, return a pointer to the start of the
            ** position-list (instead of a pointer to the start of a list
            ** of offsets associated with a specific column).
            */
            return pCsr;
          }
          while( iThis<iCol ){
            fts3ColumnlistCopy(0, &pCsr);
            if( *pCsr==0x00 ) return 0;
            pCsr++;
            pCsr += sqlite3Fts3GetVarint32(pCsr, &iThis);
          }
          if( iCol==iThis && (*pCsr&0xFE) ) return pCsr;
        }
        return 0;
      }
    }
  }

  return 0;
}

/*
** Helper function used by the implementation of the overloaded snippet(),
** offsets() and optimize() SQL functions.
**
** If the value passed as the third argument is a blob of size
** sizeof(Fts3Cursor*), then the blob contents are copied to the 
** output variable *ppCsr and SQLITE_OK is returned. Otherwise, an error
................................................................................
    "ALTER TABLE %Q.'%q_segdir'   RENAME TO '%q_segdir';",
    p->zDb, p->zName, zName
  );
  return rc;
}

static int fts3SavepointMethod(sqlite3_vtab *pVtab, int iSavepoint){
  Fts3Table *p = (Fts3Table*)pVtab;
  UNUSED_PARAMETER(iSavepoint);
  assert( p->inTransaction );
  assert( p->mxSavepoint < iSavepoint );
  TESTONLY( p->mxSavepoint = iSavepoint );
  return sqlite3Fts3PendingTermsFlush(p);

}
static int fts3ReleaseMethod(sqlite3_vtab *pVtab, int iSavepoint){
  TESTONLY( Fts3Table *p = (Fts3Table*)pVtab );
  UNUSED_PARAMETER(iSavepoint);
  UNUSED_PARAMETER(pVtab);
  assert( p->inTransaction );
  assert( p->mxSavepoint >= iSavepoint );
................................................................................
  const sqlite3_api_routines *pApi
){
  SQLITE_EXTENSION_INIT2(pApi)
  return sqlite3Fts3Init(db);
}
#endif























































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































#endif

/************** End of fts3.c ************************************************/
/************** Begin file fts3_aux.c ****************************************/
/*
** 2011 Jan 27
**
................................................................................
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
*/

#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)


typedef struct Fts3auxTable Fts3auxTable;
typedef struct Fts3auxCursor Fts3auxCursor;

struct Fts3auxTable {
  sqlite3_vtab base;              /* Base class used by SQLite core */
  Fts3Table *pFts3Tab;
};

struct Fts3auxCursor {
  sqlite3_vtab_cursor base;       /* Base class used by SQLite core */
  Fts3SegReaderCursor csr;        /* Must be right after "base" */
  Fts3SegFilter filter;
  char *zStop;
  int nStop;                      /* Byte-length of string zStop */
  int isEof;                      /* True if cursor is at EOF */
  sqlite3_int64 iRowid;           /* Current rowid */

  int iCol;                       /* Current value of 'col' column */
................................................................................
  if( !p ) return SQLITE_NOMEM;
  memset(p, 0, nByte);

  p->pFts3Tab = (Fts3Table *)&p[1];
  p->pFts3Tab->zDb = (char *)&p->pFts3Tab[1];
  p->pFts3Tab->zName = &p->pFts3Tab->zDb[nDb+1];
  p->pFts3Tab->db = db;


  memcpy((char *)p->pFts3Tab->zDb, zDb, nDb);
  memcpy((char *)p->pFts3Tab->zName, zFts3, nFts3);
  sqlite3Fts3Dequote((char *)p->pFts3Tab->zName);

  *ppVtab = (sqlite3_vtab *)p;
  return SQLITE_OK;
................................................................................
  if( idxNum&FTS4AUX_LE_CONSTRAINT ){
    int iIdx = (idxNum&FTS4AUX_GE_CONSTRAINT) ? 1 : 0;
    pCsr->zStop = sqlite3_mprintf("%s", sqlite3_value_text(apVal[iIdx]));
    pCsr->nStop = sqlite3_value_bytes(apVal[iIdx]);
    if( pCsr->zStop==0 ) return SQLITE_NOMEM;
  }

  rc = sqlite3Fts3SegReaderCursor(pFts3, FTS3_SEGCURSOR_ALL,
      pCsr->filter.zTerm, pCsr->filter.nTerm, 0, isScan, &pCsr->csr
  );
  if( rc==SQLITE_OK ){
    rc = sqlite3Fts3SegReaderStart(pFts3, &pCsr->csr, &pCsr->filter);
  }

  if( rc==SQLITE_OK ) rc = fts3auxNextMethod(pCursor);
................................................................................

/*
** Default span for NEAR operators.
*/
#define SQLITE_FTS3_DEFAULT_NEAR_PARAM 10










typedef struct ParseContext ParseContext;
struct ParseContext {
  sqlite3_tokenizer *pTokenizer;      /* Tokenizer module */
  const char **azCol;                 /* Array of column names for fts3 table */
  int nCol;                           /* Number of entries in azCol[] */
  int iDefaultCol;                    /* Default column to query */

  sqlite3_context *pCtx;              /* Write error message here */
  int nNest;                          /* Number of nested brackets */
};

/*
** This function is equivalent to the standard isspace() function. 
**
................................................................................
        memcpy(pRet->pPhrase->aToken[0].z, zToken, nToken);

        if( iEnd<n && z[iEnd]=='*' ){
          pRet->pPhrase->aToken[0].isPrefix = 1;
          iEnd++;
        }
        if( !sqlite3_fts3_enable_parentheses && iStart>0 && z[iStart-1]=='-' ){
          pRet->pPhrase->isNot = 1;
        }
      }
      nConsumed = iEnd;
    }

    pModule->xClose(pCursor);
  }
................................................................................
  sqlite3_tokenizer_module const *pModule = pTokenizer->pModule;
  int rc;
  Fts3Expr *p = 0;
  sqlite3_tokenizer_cursor *pCursor = 0;
  char *zTemp = 0;
  int nTemp = 0;























  rc = pModule->xOpen(pTokenizer, zInput, nInput, &pCursor);
  if( rc==SQLITE_OK ){
    int ii;
    pCursor->pTokenizer = pTokenizer;
    for(ii=0; rc==SQLITE_OK; ii++){
      const char *zToken;
      int nToken, iBegin, iEnd, iPos;
      rc = pModule->xNext(pCursor, &zToken, &nToken, &iBegin, &iEnd, &iPos);
      if( rc==SQLITE_OK ){
        int nByte = sizeof(Fts3Expr) + sizeof(Fts3Phrase);
        p = fts3ReallocOrFree(p, nByte+ii*sizeof(Fts3PhraseToken));
        zTemp = fts3ReallocOrFree(zTemp, nTemp + nToken);
        if( !p || !zTemp ){
          goto no_mem;
        }
        if( ii==0 ){
          memset(p, 0, nByte);
          p->pPhrase = (Fts3Phrase *)&p[1];
        }
        p->pPhrase = (Fts3Phrase *)&p[1];
        memset(&p->pPhrase->aToken[ii], 0, sizeof(Fts3PhraseToken));
        p->pPhrase->nToken = ii+1;
        p->pPhrase->aToken[ii].n = nToken;
        memcpy(&zTemp[nTemp], zToken, nToken);
        nTemp += nToken;
        if( iEnd<nInput && zInput[iEnd]=='*' ){
          p->pPhrase->aToken[ii].isPrefix = 1;
        }else{
          p->pPhrase->aToken[ii].isPrefix = 0;
        }
      }
    }

    pModule->xClose(pCursor);
    pCursor = 0;
  }

  if( rc==SQLITE_DONE ){
    int jj;
    char *zNew = NULL;
    int nNew = 0;
    int nByte = sizeof(Fts3Expr) + sizeof(Fts3Phrase);
    nByte += (p?(p->pPhrase->nToken-1):0) * sizeof(Fts3PhraseToken);
    p = fts3ReallocOrFree(p, nByte + nTemp);
    if( !p ){
      goto no_mem;
    }
    if( zTemp ){
      zNew = &(((char *)p)[nByte]);
      memcpy(zNew, zTemp, nTemp);
    }else{
      memset(p, 0, nByte+nTemp);
    }
    p->pPhrase = (Fts3Phrase *)&p[1];
    for(jj=0; jj<p->pPhrase->nToken; jj++){
      p->pPhrase->aToken[jj].z = &zNew[nNew];
      nNew += p->pPhrase->aToken[jj].n;
    }
    sqlite3_free(zTemp);
    p->eType = FTSQUERY_PHRASE;
    p->pPhrase->iColumn = pParse->iDefaultCol;
    rc = SQLITE_OK;
  }

  *ppExpr = p;
  return rc;
no_mem:

................................................................................
  int iCol;
  int iColLen;
  int rc;
  Fts3Expr *pRet = 0;

  const char *zInput = z;
  int nInput = n;



  /* Skip over any whitespace before checking for a keyword, an open or
  ** close bracket, or a quoted string. 
  */
  while( nInput>0 && fts3isspace(*zInput) ){
    nInput--;
    zInput++;
................................................................................
    Fts3Expr *p = 0;
    int nByte = 0;
    rc = getNextNode(pParse, zIn, nIn, &p, &nByte);
    if( rc==SQLITE_OK ){
      int isPhrase;

      if( !sqlite3_fts3_enable_parentheses 
       && p->eType==FTSQUERY_PHRASE && p->pPhrase->isNot 
      ){
        /* Create an implicit NOT operator. */
        Fts3Expr *pNot = fts3MallocZero(sizeof(Fts3Expr));
        if( !pNot ){
          sqlite3Fts3ExprFree(p);
          rc = SQLITE_NOMEM;
          goto exprparse_out;
................................................................................
        if( pNotBranch ){
          pNot->pLeft = pNotBranch;
        }
        pNotBranch = pNot;
        p = pPrev;
      }else{
        int eType = p->eType;
        assert( eType!=FTSQUERY_PHRASE || !p->pPhrase->isNot );
        isPhrase = (eType==FTSQUERY_PHRASE || p->pLeft);

        /* The isRequirePhrase variable is set to true if a phrase or
        ** an expression contained in parenthesis is required. If a
        ** binary operator (AND, OR, NOT or NEAR) is encounted when
        ** isRequirePhrase is set, this is a syntax error.
        */
................................................................................
}

/*
** Free a parsed fts3 query expression allocated by sqlite3Fts3ExprParse().
*/
SQLITE_PRIVATE void sqlite3Fts3ExprFree(Fts3Expr *p){
  if( p ){

    sqlite3Fts3ExprFree(p->pLeft);
    sqlite3Fts3ExprFree(p->pRight);

    sqlite3_free(p->aDoclist);
    sqlite3_free(p);
  }
}

/****************************************************************************
*****************************************************************************
** Everything after this point is just test code.
................................................................................
*/
static char *exprToString(Fts3Expr *pExpr, char *zBuf){
  switch( pExpr->eType ){
    case FTSQUERY_PHRASE: {
      Fts3Phrase *pPhrase = pExpr->pPhrase;
      int i;
      zBuf = sqlite3_mprintf(
          "%zPHRASE %d %d", zBuf, pPhrase->iColumn, pPhrase->isNot);
      for(i=0; zBuf && i<pPhrase->nToken; i++){
        zBuf = sqlite3_mprintf("%z %.*s%s", zBuf, 
            pPhrase->aToken[i].n, pPhrase->aToken[i].z,
            (pPhrase->aToken[i].isPrefix?"+":"")
        );
      }
      return zBuf;
................................................................................
**     * The FTS3 module is being built as an extension
**       (in which case SQLITE_CORE is not defined), or
**
**     * The FTS3 module is being built into the core of
**       SQLite (in which case SQLITE_ENABLE_FTS3 is defined).
*/
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)




/*
** Class derived from sqlite3_tokenizer
*/
typedef struct porter_tokenizer {
................................................................................
**
**     * The FTS3 module is being built as an extension
**       (in which case SQLITE_CORE is not defined), or
**
**     * The FTS3 module is being built into the core of
**       SQLite (in which case SQLITE_ENABLE_FTS3 is defined).
*/
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

#ifndef SQLITE_CORE
  SQLITE_EXTENSION_INIT1
#endif




/*
** Implementation of the SQL scalar function for accessing the underlying 
** hash table. This function may be called as follows:
**
**   SELECT <function-name>(<key-name>);
................................................................................
  Fts3Hash *pHash,                /* Tokenizer hash table */
  const char *zArg,               /* Tokenizer name */
  sqlite3_tokenizer **ppTok,      /* OUT: Tokenizer (if applicable) */
  char **pzErr                    /* OUT: Set to malloced error message */
){
  int rc;
  char *z = (char *)zArg;
  int n;
  char *zCopy;
  char *zEnd;                     /* Pointer to nul-term of zCopy */
  sqlite3_tokenizer_module *m;

  zCopy = sqlite3_mprintf("%s", zArg);
  if( !zCopy ) return SQLITE_NOMEM;
  zEnd = &zCopy[strlen(zCopy)];
................................................................................
**     * The FTS3 module is being built into the core of
**       SQLite (in which case SQLITE_ENABLE_FTS3 is defined).
*/
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)




typedef struct simple_tokenizer {
  sqlite3_tokenizer base;
  char delim[128];             /* flag ASCII delimiters */
} simple_tokenizer;

typedef struct simple_tokenizer_cursor {
  sqlite3_tokenizer_cursor base;
................................................................................
**
** This means that if we have a pointer into a buffer containing node data,
** it is always safe to read up to two varints from it without risking an
** overread, even if the node data is corrupted.
*/
#define FTS3_NODE_PADDING (FTS3_VARINT_MAX*2)




























typedef struct PendingList PendingList;
typedef struct SegmentNode SegmentNode;
typedef struct SegmentWriter SegmentWriter;

/*
** Data structure used while accumulating terms in the pending-terms hash
** table. The hash table entry maps from term (a string) to a malloc'd
** instance of this structure.
*/
struct PendingList {
  int nData;
  char *aData;
  int nSpace;
  sqlite3_int64 iLastDocid;
  sqlite3_int64 iLastCol;
................................................................................
** a contiguous set of segment b-tree leaf nodes. Although the details of
** this structure are only manipulated by code in this file, opaque handles
** of type Fts3SegReader* are also used by code in fts3.c to iterate through
** terms when querying the full-text index. See functions:
**
**   sqlite3Fts3SegReaderNew()
**   sqlite3Fts3SegReaderFree()
**   sqlite3Fts3SegReaderCost()
**   sqlite3Fts3SegReaderIterate()
**
** Methods used to manipulate Fts3SegReader structures:
**
**   fts3SegReaderNext()
**   fts3SegReaderFirstDocid()
**   fts3SegReaderNextDocid()
................................................................................
  sqlite3_int64 iStartBlock;      /* Rowid of first leaf block to traverse */
  sqlite3_int64 iLeafEndBlock;    /* Rowid of final leaf block to traverse */
  sqlite3_int64 iEndBlock;        /* Rowid of final block in segment (or 0) */
  sqlite3_int64 iCurrentBlock;    /* Current leaf block (or 0) */

  char *aNode;                    /* Pointer to node data (or NULL) */
  int nNode;                      /* Size of buffer at aNode (or 0) */



  Fts3HashElem **ppNextElem;

  /* Variables set by fts3SegReaderNext(). These may be read directly
  ** by the caller. They are valid from the time SegmentReaderNew() returns
  ** until SegmentReaderNext() returns something other than SQLITE_OK
  ** (i.e. SQLITE_DONE).
  */
  int nTerm;                      /* Number of bytes in current term */
  char *zTerm;                    /* Pointer to current term */
  int nTermAlloc;                 /* Allocated size of zTerm buffer */
  char *aDoclist;                 /* Pointer to doclist of current entry */
  int nDoclist;                   /* Size of doclist in current entry */

  /* The following variables are used to iterate through the current doclist */


  char *pOffsetList;

  sqlite3_int64 iDocid;
};

#define fts3SegReaderIsPending(p) ((p)->ppNextElem!=0)
#define fts3SegReaderIsRootOnly(p) ((p)->aNode==(char *)&(p)[1])

/*
................................................................................
** the interior part of the segment b+-tree structures (everything except
** the leaf nodes). These functions and type are only ever used by code
** within the fts3SegWriterXXX() family of functions described above.
**
**   fts3NodeAddTerm()
**   fts3NodeWrite()
**   fts3NodeFree()








*/
struct SegmentNode {
  SegmentNode *pParent;           /* Parent node (or NULL for root node) */
  SegmentNode *pRight;            /* Pointer to right-sibling */
  SegmentNode *pLeftmost;         /* Pointer to left-most node of this depth */
  int nEntry;                     /* Number of terms written to node so far */
  char *zTerm;                    /* Pointer to previous term buffer */
................................................................................
#define SQL_DELETE_ALL_STAT            6
#define SQL_SELECT_CONTENT_BY_ROWID    7
#define SQL_NEXT_SEGMENT_INDEX         8
#define SQL_INSERT_SEGMENTS            9
#define SQL_NEXT_SEGMENTS_ID          10
#define SQL_INSERT_SEGDIR             11
#define SQL_SELECT_LEVEL              12
#define SQL_SELECT_ALL_LEVEL          13
#define SQL_SELECT_LEVEL_COUNT        14
#define SQL_SELECT_SEGDIR_COUNT_MAX   15
#define SQL_DELETE_SEGDIR_BY_LEVEL    16
#define SQL_DELETE_SEGMENTS_RANGE     17
#define SQL_CONTENT_INSERT            18
#define SQL_DELETE_DOCSIZE            19
#define SQL_REPLACE_DOCSIZE           20
#define SQL_SELECT_DOCSIZE            21
#define SQL_SELECT_DOCTOTAL           22
#define SQL_REPLACE_DOCTOTAL          23






/*
** This function is used to obtain an SQLite prepared statement handle
** for the statement identified by the second argument. If successful,
** *pp is set to the requested statement handle and SQLITE_OK returned.
** Otherwise, an SQLite error code is returned and *pp is set to 0.
**
................................................................................
/* 10 */  "SELECT coalesce((SELECT max(blockid) FROM %Q.'%q_segments') + 1, 1)",
/* 11 */  "INSERT INTO %Q.'%q_segdir' VALUES(?,?,?,?,?,?)",

          /* Return segments in order from oldest to newest.*/ 
/* 12 */  "SELECT idx, start_block, leaves_end_block, end_block, root "
            "FROM %Q.'%q_segdir' WHERE level = ? ORDER BY idx ASC",
/* 13 */  "SELECT idx, start_block, leaves_end_block, end_block, root "

            "FROM %Q.'%q_segdir' ORDER BY level DESC, idx ASC",

/* 14 */  "SELECT count(*) FROM %Q.'%q_segdir' WHERE level = ?",
/* 15 */  "SELECT count(*), max(level) FROM %Q.'%q_segdir'",

/* 16 */  "DELETE FROM %Q.'%q_segdir' WHERE level = ?",
/* 17 */  "DELETE FROM %Q.'%q_segments' WHERE blockid BETWEEN ? AND ?",
/* 18 */  "INSERT INTO %Q.'%q_content' VALUES(%s)",
/* 19 */  "DELETE FROM %Q.'%q_docsize' WHERE docid = ?",
/* 20 */  "REPLACE INTO %Q.'%q_docsize' VALUES(?,?)",
/* 21 */  "SELECT size FROM %Q.'%q_docsize' WHERE docid=?",
/* 22 */  "SELECT value FROM %Q.'%q_stat' WHERE id=0",
/* 23 */  "REPLACE INTO %Q.'%q_stat' VALUES(0,?)",





  };
  int rc = SQLITE_OK;
  sqlite3_stmt *pStmt;

  assert( SizeofArray(azSql)==SizeofArray(p->aStmt) );
  assert( eStmt<SizeofArray(azSql) && eStmt>=0 );
  
................................................................................
**
**   0: idx
**   1: start_block
**   2: leaves_end_block
**   3: end_block
**   4: root
*/
SQLITE_PRIVATE int sqlite3Fts3AllSegdirs(Fts3Table *p, int iLevel, sqlite3_stmt **ppStmt){





  int rc;
  sqlite3_stmt *pStmt = 0;





  if( iLevel<0 ){

    rc = fts3SqlStmt(p, SQL_SELECT_ALL_LEVEL, &pStmt, 0);




  }else{

    rc = fts3SqlStmt(p, SQL_SELECT_LEVEL, &pStmt, 0);

    if( rc==SQLITE_OK ) sqlite3_bind_int(pStmt, 1, iLevel);

  }
  *ppStmt = pStmt;
  return rc;
}


/*
................................................................................
  *pRc = rc;
  if( p!=*pp ){
    *pp = p;
    return 1;
  }
  return 0;
}










































/*
** Tokenize the nul-terminated string zText and add all tokens to the
** pending-terms hash-table. The docid used is that currently stored in
** p->iPrevDocid, and the column is specified by argument iCol.
**
** If successful, SQLITE_OK is returned. Otherwise, an SQLite error code.
................................................................................
  }
  pCsr->pTokenizer = pTokenizer;

  xNext = pModule->xNext;
  while( SQLITE_OK==rc
      && SQLITE_OK==(rc = xNext(pCsr, &zToken, &nToken, &iStart, &iEnd, &iPos))
  ){
    PendingList *pList;
 
    if( iPos>=nWord ) nWord = iPos+1;

    /* Positions cannot be negative; we use -1 as a terminator internally.
    ** Tokens must have a non-zero length.
    */
    if( iPos<0 || !zToken || nToken<=0 ){
      rc = SQLITE_ERROR;
      break;
    }

    pList = (PendingList *)fts3HashFind(&p->pendingTerms, zToken, nToken);
    if( pList ){
      p->nPendingData -= (pList->nData + nToken + sizeof(Fts3HashElem));
    }
    if( fts3PendingListAppend(&pList, p->iPrevDocid, iCol, iPos, &rc) ){
      if( pList==fts3HashInsert(&p->pendingTerms, zToken, nToken, pList) ){
        /* Malloc failed while inserting the new entry. This can only 
        ** happen if there was no previous entry for this token.
        */
        assert( 0==fts3HashFind(&p->pendingTerms, zToken, nToken) );
        sqlite3_free(pList);
        rc = SQLITE_NOMEM;
      }
    }
    if( rc==SQLITE_OK ){
      p->nPendingData += (pList->nData + nToken + sizeof(Fts3HashElem));
    }
  }

  pModule->xClose(pCsr);
  *pnWord = nWord;
  return (rc==SQLITE_DONE ? SQLITE_OK : rc);
}
................................................................................
    if( rc!=SQLITE_OK ) return rc;
  }
  p->iPrevDocid = iDocid;
  return SQLITE_OK;
}

/*
** Discard the contents of the pending-terms hash table. 
*/
SQLITE_PRIVATE void sqlite3Fts3PendingTermsClear(Fts3Table *p){


  Fts3HashElem *pElem;

  for(pElem=fts3HashFirst(&p->pendingTerms); pElem; pElem=fts3HashNext(pElem)){
    sqlite3_free(fts3HashData(pElem));

  }
  fts3HashClear(&p->pendingTerms);

  p->nPendingData = 0;
}

/*
** This function is called by the xUpdate() method as part of an INSERT
** operation. It adds entries for each term in the new record to the
** pendingTerms hash table.
................................................................................
  *pRC = rc;
}

/*
** Forward declaration to account for the circular dependency between
** functions fts3SegmentMerge() and fts3AllocateSegdirIdx().
*/
static int fts3SegmentMerge(Fts3Table *, int);

/* 
** This function allocates a new level iLevel index in the segdir table.
** Usually, indexes are allocated within a level sequentially starting
** with 0, so the allocated index is one greater than the value returned
** by:
**
................................................................................
** However, if there are already FTS3_MERGE_COUNT indexes at the requested
** level, they are merged into a single level (iLevel+1) segment and the 
** allocated index is 0.
**
** If successful, *piIdx is set to the allocated index slot and SQLITE_OK
** returned. Otherwise, an SQLite error code is returned.
*/
static int fts3AllocateSegdirIdx(Fts3Table *p, int iLevel, int *piIdx){





  int rc;                         /* Return Code */
  sqlite3_stmt *pNextIdx;         /* Query for next idx at level iLevel */
  int iNext = 0;                  /* Result of query pNextIdx */

  /* Set variable iNext to the next available segdir index at level iLevel. */
  rc = fts3SqlStmt(p, SQL_NEXT_SEGMENT_INDEX, &pNextIdx, 0);
  if( rc==SQLITE_OK ){
    sqlite3_bind_int(pNextIdx, 1, iLevel);
    if( SQLITE_ROW==sqlite3_step(pNextIdx) ){
      iNext = sqlite3_column_int(pNextIdx, 0);
    }
    rc = sqlite3_reset(pNextIdx);
  }

  if( rc==SQLITE_OK ){
    /* If iNext is FTS3_MERGE_COUNT, indicating that level iLevel is already
    ** full, merge all segments in level iLevel into a single iLevel+1
    ** segment and allocate (newly freed) index 0 at level iLevel. Otherwise,
    ** if iNext is less than FTS3_MERGE_COUNT, allocate index iNext.
    */
    if( iNext>=FTS3_MERGE_COUNT ){
      rc = fts3SegmentMerge(p, iLevel);
      *piIdx = 0;
    }else{
      *piIdx = iNext;
    }
  }

  return rc;
................................................................................
** method (xFilter etc.) that may directly or indirectly call this function
** must call sqlite3Fts3SegmentsClose() before returning.
*/
SQLITE_PRIVATE int sqlite3Fts3ReadBlock(
  Fts3Table *p,                   /* FTS3 table handle */
  sqlite3_int64 iBlockid,         /* Access the row with blockid=$iBlockid */
  char **paBlob,                  /* OUT: Blob data in malloc'd buffer */
  int *pnBlob                     /* OUT: Size of blob data */

){
  int rc;                         /* Return code */

  /* pnBlob must be non-NULL. paBlob may be NULL or non-NULL. */
  assert( pnBlob);

  if( p->pSegments ){
................................................................................
    rc = sqlite3_blob_open(
       p->db, p->zDb, p->zSegmentsTbl, "block", iBlockid, 0, &p->pSegments
    );
  }

  if( rc==SQLITE_OK ){
    int nByte = sqlite3_blob_bytes(p->pSegments);

    if( paBlob ){
      char *aByte = sqlite3_malloc(nByte + FTS3_NODE_PADDING);
      if( !aByte ){
        rc = SQLITE_NOMEM;
      }else{




        rc = sqlite3_blob_read(p->pSegments, aByte, nByte, 0);
        memset(&aByte[nByte], 0, FTS3_NODE_PADDING);
        if( rc!=SQLITE_OK ){
          sqlite3_free(aByte);
          aByte = 0;
        }
      }
      *paBlob = aByte;
    }
    *pnBlob = nByte;
  }

  return rc;
}

/*
** Close the blob handle at p->pSegments, if it is open. See comments above
** the sqlite3Fts3ReadBlock() function for details.
*/
SQLITE_PRIVATE void sqlite3Fts3SegmentsClose(Fts3Table *p){
  sqlite3_blob_close(p->pSegments);
  p->pSegments = 0;
}






































/*
** Move the iterator passed as the first argument to the next term in the
** segment. If successful, SQLITE_OK is returned. If there is no next term,
** SQLITE_DONE. Otherwise, an SQLite error code.
*/
static int fts3SegReaderNext(Fts3Table *p, Fts3SegReader *pReader){





  char *pNext;                    /* Cursor variable */
  int nPrefix;                    /* Number of bytes in term prefix */
  int nSuffix;                    /* Number of bytes in term suffix */

  if( !pReader->aDoclist ){
    pNext = pReader->aNode;
  }else{
    pNext = &pReader->aDoclist[pReader->nDoclist];
  }

  if( !pNext || pNext>=&pReader->aNode[pReader->nNode] ){
    int rc;                       /* Return code from Fts3ReadBlock() */

    if( fts3SegReaderIsPending(pReader) ){
      Fts3HashElem *pElem = *(pReader->ppNextElem);
      if( pElem==0 ){
        pReader->aNode = 0;
      }else{
        PendingList *pList = (PendingList *)fts3HashData(pElem);
................................................................................
        assert( pReader->aNode );
      }
      return SQLITE_OK;
    }

    if( !fts3SegReaderIsRootOnly(pReader) ){
      sqlite3_free(pReader->aNode);


    }
    pReader->aNode = 0;

    /* If iCurrentBlock>=iLeafEndBlock, this is an EOF condition. All leaf 
    ** blocks have already been traversed.  */
    assert( pReader->iCurrentBlock<=pReader->iLeafEndBlock );
    if( pReader->iCurrentBlock>=pReader->iLeafEndBlock ){
      return SQLITE_OK;
    }

    rc = sqlite3Fts3ReadBlock(
        p, ++pReader->iCurrentBlock, &pReader->aNode, &pReader->nNode

    );
    if( rc!=SQLITE_OK ) return rc;





    pNext = pReader->aNode;
  }
  





  /* Because of the FTS3_NODE_PADDING bytes of padding, the following is 
  ** safe (no risk of overread) even if the node data is corrupted.  
  */
  pNext += sqlite3Fts3GetVarint32(pNext, &nPrefix);
  pNext += sqlite3Fts3GetVarint32(pNext, &nSuffix);
  if( nPrefix<0 || nSuffix<=0 
   || &pNext[nSuffix]>&pReader->aNode[pReader->nNode] 
  ){
    return SQLITE_CORRUPT_VTAB;
  }
................................................................................
    char *zNew = sqlite3_realloc(pReader->zTerm, nNew);
    if( !zNew ){
      return SQLITE_NOMEM;
    }
    pReader->zTerm = zNew;
    pReader->nTermAlloc = nNew;
  }




  memcpy(&pReader->zTerm[nPrefix], pNext, nSuffix);
  pReader->nTerm = nPrefix+nSuffix;
  pNext += nSuffix;
  pNext += sqlite3Fts3GetVarint32(pNext, &pReader->nDoclist);
  pReader->aDoclist = pNext;
  pReader->pOffsetList = 0;

  /* Check that the doclist does not appear to extend past the end of the
  ** b-tree node. And that the final byte of the doclist is 0x00. If either 
  ** of these statements is untrue, then the data structure is corrupt.
  */
  if( &pReader->aDoclist[pReader->nDoclist]>&pReader->aNode[pReader->nNode] 
   || pReader->aDoclist[pReader->nDoclist-1]
  ){
    return SQLITE_CORRUPT_VTAB;
  }
  return SQLITE_OK;
}

/*
** Set the SegReader to point to the first docid in the doclist associated
** with the current term.
*/
static void fts3SegReaderFirstDocid(Fts3SegReader *pReader){
  int n;
  assert( pReader->aDoclist );
  assert( !pReader->pOffsetList );











  n = sqlite3Fts3GetVarint(pReader->aDoclist, &pReader->iDocid);
  pReader->pOffsetList = &pReader->aDoclist[n];



}

/*
** Advance the SegReader to point to the next docid in the doclist
** associated with the current term.
** 
** If arguments ppOffsetList and pnOffsetList are not NULL, then 
** *ppOffsetList is set to point to the first column-offset list
** in the doclist entry (i.e. immediately past the docid varint).
** *pnOffsetList is set to the length of the set of column-offset
** lists, not including the nul-terminator byte. For example:
*/
static void fts3SegReaderNextDocid(

  Fts3SegReader *pReader,
  char **ppOffsetList,
  int *pnOffsetList
){

  char *p = pReader->pOffsetList;
  char c = 0;
























  /* Pointer p currently points at the first byte of an offset list. The
  ** following two lines advance it to point one byte past the end of
  ** the same offset list.







  */
  while( *p | c ) c = *p++ & 0x80;






  p++;

  /* If required, populate the output variables with a pointer to and the
  ** size of the previous offset-list.
  */
  if( ppOffsetList ){
    *ppOffsetList = pReader->pOffsetList;
    *pnOffsetList = (int)(p - pReader->pOffsetList - 1);
  }



  /* If there are no more entries in the doclist, set pOffsetList to
  ** NULL. Otherwise, set Fts3SegReader.iDocid to the next docid and
  ** Fts3SegReader.pOffsetList to point to the next offset list before
  ** returning.
  */
  if( p>=&pReader->aDoclist[pReader->nDoclist] ){

    pReader->pOffsetList = 0;
  }else{


    sqlite3_int64 iDelta;
    pReader->pOffsetList = p + sqlite3Fts3GetVarint(p, &iDelta);



    pReader->iDocid += iDelta;
  }
}

/*
** This function is called to estimate the amount of data that will be 
** loaded from the disk If SegReaderIterate() is called on this seg-reader,
** in units of average document size.
** 
** This can be used as follows: If the caller has a small doclist that 
** contains references to N documents, and is considering merging it with
** a large doclist (size X "average documents"), it may opt not to load
** the large doclist if X>N.
*/






SQLITE_PRIVATE int sqlite3Fts3SegReaderCost(
  Fts3Cursor *pCsr,               /* FTS3 cursor handle */
  Fts3SegReader *pReader,         /* Segment-reader handle */
  int *pnCost                     /* IN/OUT: Number of bytes read */


){
  Fts3Table *p = (Fts3Table*)pCsr->base.pVtab;


  int rc = SQLITE_OK;             /* Return code */
  int nCost = 0;                  /* Cost in bytes to return */
  int pgsz = p->nPgsz;            /* Database page size */

  /* If this seg-reader is reading the pending-terms table, or if all data
  ** for the segment is stored on the root page of the b-tree, then the cost
  ** is zero. In this case all required data is already in main memory.
  */
  if( p->bHasStat 




   && !fts3SegReaderIsPending(pReader) 
   && !fts3SegReaderIsRootOnly(pReader) 
  ){
    int nBlob = 0;
    sqlite3_int64 iBlock;

    if( pCsr->nRowAvg==0 ){
      /* The average document size, which is required to calculate the cost
      ** of each doclist, has not yet been determined. Read the required 
      ** data from the %_stat table to calculate it.
      **
      ** Entry 0 of the %_stat table is a blob containing (nCol+1) FTS3 
      ** varints, where nCol is the number of columns in the FTS3 table.
      ** The first varint is the number of documents currently stored in
      ** the table. The following nCol varints contain the total amount of
      ** data stored in all rows of each column of the table, from left
      ** to right.
      */
      sqlite3_stmt *pStmt;
      sqlite3_int64 nDoc = 0;
      sqlite3_int64 nByte = 0;
      const char *pEnd;
      const char *a;

      rc = sqlite3Fts3SelectDoctotal(p, &pStmt);
      if( rc!=SQLITE_OK ) return rc;
      a = sqlite3_column_blob(pStmt, 0);
      assert( a );

      pEnd = &a[sqlite3_column_bytes(pStmt, 0)];
      a += sqlite3Fts3GetVarint(a, &nDoc);
      while( a<pEnd ){
        a += sqlite3Fts3GetVarint(a, &nByte);
      }
      if( nDoc==0 || nByte==0 ){
        sqlite3_reset(pStmt);
        return SQLITE_CORRUPT_VTAB;
      }

      pCsr->nRowAvg = (int)(((nByte / nDoc) + pgsz) / pgsz);
      assert( pCsr->nRowAvg>0 ); 
      rc = sqlite3_reset(pStmt);
      if( rc!=SQLITE_OK ) return rc;
    }

    /* Assume that a blob flows over onto overflow pages if it is larger
    ** than (pgsz-35) bytes in size (the file-format documentation
    ** confirms this).
    */
    for(iBlock=pReader->iStartBlock; iBlock<=pReader->iLeafEndBlock; iBlock++){

      rc = sqlite3Fts3ReadBlock(p, iBlock, 0, &nBlob);
      if( rc!=SQLITE_OK ) break;
      if( (nBlob+35)>pgsz ){
        int nOvfl = (nBlob + 34)/pgsz;
        nCost += ((nOvfl + pCsr->nRowAvg - 1)/pCsr->nRowAvg);
      }
    }
  }

  *pnCost += nCost;

  return rc;
}

/*
** Free all allocations associated with the iterator passed as the 
** second argument.
*/
SQLITE_PRIVATE void sqlite3Fts3SegReaderFree(Fts3SegReader *pReader){
  if( pReader && !fts3SegReaderIsPending(pReader) ){
    sqlite3_free(pReader->zTerm);
    if( !fts3SegReaderIsRootOnly(pReader) ){
      sqlite3_free(pReader->aNode);

    }
  }
  sqlite3_free(pReader);
}

/*
** Allocate a new SegReader object.
................................................................................
  }
  return c;
}

/*
** This function is used to allocate an Fts3SegReader that iterates through
** a subset of the terms stored in the Fts3Table.pendingTerms array.















*/
SQLITE_PRIVATE int sqlite3Fts3SegReaderPending(
  Fts3Table *p,                   /* Virtual table handle */

  const char *zTerm,              /* Term to search for */
  int nTerm,                      /* Size of buffer zTerm */
  int isPrefix,                   /* True for a term-prefix query */
  Fts3SegReader **ppReader        /* OUT: SegReader for pending-terms */
){
  Fts3SegReader *pReader = 0;     /* Fts3SegReader object to return */
  Fts3HashElem **aElem = 0;       /* Array of term hash entries to scan */
  int nElem = 0;                  /* Size of array at aElem */
  int rc = SQLITE_OK;             /* Return Code */



  if( isPrefix ){
    int nAlloc = 0;               /* Size of allocated array at aElem */
    Fts3HashElem *pE = 0;         /* Iterator variable */

    for(pE=fts3HashFirst(&p->pendingTerms); pE; pE=fts3HashNext(pE)){
      char *zKey = (char *)fts3HashKey(pE);
      int nKey = fts3HashKeysize(pE);
      if( nTerm==0 || (nKey>=nTerm && 0==memcmp(zKey, zTerm, nTerm)) ){
        if( nElem==nAlloc ){
          Fts3HashElem **aElem2;
          nAlloc += 16;
          aElem2 = (Fts3HashElem **)sqlite3_realloc(
................................................................................
          if( !aElem2 ){
            rc = SQLITE_NOMEM;
            nElem = 0;
            break;
          }
          aElem = aElem2;
        }

        aElem[nElem++] = pE;
      }
    }

    /* If more than one term matches the prefix, sort the Fts3HashElem
    ** objects in term order using qsort(). This uses the same comparison
    ** callback as is used when flushing terms to disk.
    */
    if( nElem>1 ){
      qsort(aElem, nElem, sizeof(Fts3HashElem *), fts3CompareElemByTerm);
    }

  }else{


    Fts3HashElem *pE = fts3HashFindElem(&p->pendingTerms, zTerm, nTerm);
    if( pE ){
      aElem = &pE;
      nElem = 1;
    }
  }

  if( nElem>0 ){
................................................................................
      memset(pReader, 0, nByte);
      pReader->iIdx = 0x7FFFFFFF;
      pReader->ppNextElem = (Fts3HashElem **)&pReader[1];
      memcpy(pReader->ppNextElem, aElem, nElem*sizeof(Fts3HashElem *));
    }
  }

  if( isPrefix ){
    sqlite3_free(aElem);
  }
  *ppReader = pReader;
  return rc;
}

/*
................................................................................
  int rc = (pLhs->pOffsetList==0)-(pRhs->pOffsetList==0);
  if( rc==0 ){
    if( pLhs->iDocid==pRhs->iDocid ){
      rc = pRhs->iIdx - pLhs->iIdx;
    }else{
      rc = (pLhs->iDocid > pRhs->iDocid) ? 1 : -1;
    }












  }
  assert( pLhs->aNode && pRhs->aNode );
  return rc;
}

/*
** Compare the term that the Fts3SegReader object passed as the first argument
................................................................................
    }
    rc = sqlite3_reset(pStmt);
  }
  return rc;
}

/*
** Set *pnSegment to the total number of segments in the database. Set
** *pnMax to the largest segment level in the database (segment levels


** are stored in the 'level' column of the %_segdir table).
**
** Return SQLITE_OK if successful, or an SQLite error code if not.
*/
static int fts3SegmentCountMax(Fts3Table *p, int *pnSegment, int *pnMax){
  sqlite3_stmt *pStmt;
  int rc;








  rc = fts3SqlStmt(p, SQL_SELECT_SEGDIR_COUNT_MAX, &pStmt, 0);
  if( rc!=SQLITE_OK ) return rc;


  if( SQLITE_ROW==sqlite3_step(pStmt) ){
    *pnSegment = sqlite3_column_int(pStmt, 0);
    *pnMax = sqlite3_column_int(pStmt, 1);
  }
  return sqlite3_reset(pStmt);
}

/*
** This function is used after merging multiple segments into a single large
** segment to delete the old, now redundant, segment b-trees. Specifically,
................................................................................
**   2) deletes all %_segdir entries with level iLevel, or all %_segdir
**      entries regardless of level if (iLevel<0).
**
** SQLITE_OK is returned if successful, otherwise an SQLite error code.
*/
static int fts3DeleteSegdir(
  Fts3Table *p,                   /* Virtual table handle */

  int iLevel,                     /* Level of %_segdir entries to delete */
  Fts3SegReader **apSegment,      /* Array of SegReader objects */
  int nReader                     /* Size of array apSegment */
){
  int rc;                         /* Return Code */
  int i;                          /* Iterator variable */
  sqlite3_stmt *pDelete;          /* SQL statement to delete rows */
................................................................................
      rc = sqlite3_reset(pDelete);
    }
  }
  if( rc!=SQLITE_OK ){
    return rc;
  }

  if( iLevel==FTS3_SEGCURSOR_ALL ){
    fts3SqlExec(&rc, p, SQL_DELETE_ALL_SEGDIR, 0);
  }else if( iLevel==FTS3_SEGCURSOR_PENDING ){

    sqlite3Fts3PendingTermsClear(p);



  }else{
    assert( iLevel>=0 );
    rc = fts3SqlStmt(p, SQL_DELETE_SEGDIR_BY_LEVEL, &pDelete, 0);
    if( rc==SQLITE_OK ){
      sqlite3_bind_int(pDelete, 1, iLevel);




      sqlite3_step(pDelete);
      rc = sqlite3_reset(pDelete);
    }
  }

  return rc;
}

/*
** When this function is called, buffer *ppList (size *pnList bytes) contains 
** a position list that may (or may not) feature multiple columns. This
................................................................................
    p += sqlite3Fts3GetVarint32(p, &iCurrent);
  }

  *ppList = pList;
  *pnList = nList;
}

























SQLITE_PRIVATE int sqlite3Fts3SegReaderStart(
  Fts3Table *p,                   /* Virtual table handle */
  Fts3SegReaderCursor *pCsr,      /* Cursor object */
  Fts3SegFilter *pFilter          /* Restrictions on range of iteration */




){



















  int i;





  /* Initialize the cursor object */
  pCsr->pFilter = pFilter;













































  /* If the Fts3SegFilter defines a specific term (or term prefix) to search 
  ** for, then advance each segment iterator until it points to a term of
  ** equal or greater value than the specified term. This prevents many
  ** unnecessary merge/sort operations for the case where single segment
  ** b-tree leaf nodes contain more than one term.
  */
  for(i=0; i<pCsr->nSegment; i++){
    int nTerm = pFilter->nTerm;
    const char *zTerm = pFilter->zTerm;
    Fts3SegReader *pSeg = pCsr->apSegment[i];
    do {
      int rc = fts3SegReaderNext(p, pSeg);
      if( rc!=SQLITE_OK ) return rc;
    }while( zTerm && fts3SegReaderTermCmp(pSeg, zTerm, nTerm)<0 );
  }

















































  fts3SegReaderSort(
      pCsr->apSegment, pCsr->nSegment, pCsr->nSegment, fts3SegReaderCmp);




  return SQLITE_OK;
}

































SQLITE_PRIVATE int sqlite3Fts3SegReaderStep(
  Fts3Table *p,                   /* Virtual table handle */
  Fts3SegReaderCursor *pCsr       /* Cursor object */
){
  int rc = SQLITE_OK;

  int isIgnoreEmpty =  (pCsr->pFilter->flags & FTS3_SEGMENT_IGNORE_EMPTY);
  int isRequirePos =   (pCsr->pFilter->flags & FTS3_SEGMENT_REQUIRE_POS);
  int isColFilter =    (pCsr->pFilter->flags & FTS3_SEGMENT_COLUMN_FILTER);
  int isPrefix =       (pCsr->pFilter->flags & FTS3_SEGMENT_PREFIX);
  int isScan =         (pCsr->pFilter->flags & FTS3_SEGMENT_SCAN);

  Fts3SegReader **apSegment = pCsr->apSegment;
  int nSegment = pCsr->nSegment;
  Fts3SegFilter *pFilter = pCsr->pFilter;




  if( pCsr->nSegment==0 ) return SQLITE_OK;

  do {
    int nMerge;
    int i;
  
    /* Advance the first pCsr->nAdvance entries in the apSegment[] array
    ** forward. Then sort the list in order of current term again.  
    */
    for(i=0; i<pCsr->nAdvance; i++){
      rc = fts3SegReaderNext(p, apSegment[i]);
      if( rc!=SQLITE_OK ) return rc;
    }
    fts3SegReaderSort(apSegment, nSegment, pCsr->nAdvance, fts3SegReaderCmp);
    pCsr->nAdvance = 0;

    /* If all the seg-readers are at EOF, we're finished. return SQLITE_OK. */
    assert( rc==SQLITE_OK );
................................................................................
        && apSegment[nMerge]->nTerm==pCsr->nTerm 
        && 0==memcmp(pCsr->zTerm, apSegment[nMerge]->zTerm, pCsr->nTerm)
    ){
      nMerge++;
    }

    assert( isIgnoreEmpty || (isRequirePos && !isColFilter) );

    if( nMerge==1 && !isIgnoreEmpty ){


      pCsr->aDoclist = apSegment[0]->aDoclist;




      pCsr->nDoclist = apSegment[0]->nDoclist;

      rc = SQLITE_ROW;
    }else{
      int nDoclist = 0;           /* Size of doclist */
      sqlite3_int64 iPrev = 0;    /* Previous docid stored in doclist */

      /* The current term of the first nMerge entries in the array
      ** of Fts3SegReader objects is the same. The doclists must be merged
      ** and a single term returned with the merged doclist.
      */
      for(i=0; i<nMerge; i++){
        fts3SegReaderFirstDocid(apSegment[i]);
      }
      fts3SegReaderSort(apSegment, nMerge, nMerge, fts3SegReaderDoclistCmp);
      while( apSegment[0]->pOffsetList ){
        int j;                    /* Number of segments that share a docid */
        char *pList;
        int nList;
        int nByte;
        sqlite3_int64 iDocid = apSegment[0]->iDocid;
        fts3SegReaderNextDocid(apSegment[0], &pList, &nList);
        j = 1;
        while( j<nMerge
            && apSegment[j]->pOffsetList
            && apSegment[j]->iDocid==iDocid
        ){
          fts3SegReaderNextDocid(apSegment[j], 0, 0);
          j++;
        }

        if( isColFilter ){
          fts3ColumnFilter(pFilter->iCol, &pList, &nList);
        }

        if( !isIgnoreEmpty || nList>0 ){












          nByte = sqlite3Fts3VarintLen(iDocid-iPrev) + (isRequirePos?nList+1:0);
          if( nDoclist+nByte>pCsr->nBuffer ){
            char *aNew;
            pCsr->nBuffer = (nDoclist+nByte)*2;
            aNew = sqlite3_realloc(pCsr->aBuffer, pCsr->nBuffer);
            if( !aNew ){
              return SQLITE_NOMEM;
            }
            pCsr->aBuffer = aNew;
          }
          nDoclist += sqlite3Fts3PutVarint(
              &pCsr->aBuffer[nDoclist], iDocid-iPrev
          );
          iPrev = iDocid;
          if( isRequirePos ){
            memcpy(&pCsr->aBuffer[nDoclist], pList, nList);
            nDoclist += nList;
            pCsr->aBuffer[nDoclist++] = '\0';
          }
        }

        fts3SegReaderSort(apSegment, nMerge, j, fts3SegReaderDoclistCmp);
      }
      if( nDoclist>0 ){
        pCsr->aDoclist = pCsr->aBuffer;
        pCsr->nDoclist = nDoclist;
        rc = SQLITE_ROW;
      }
    }
    pCsr->nAdvance = nMerge;
  }while( rc==SQLITE_OK );

  return rc;
}


SQLITE_PRIVATE void sqlite3Fts3SegReaderFinish(
  Fts3SegReaderCursor *pCsr       /* Cursor object */
){
  if( pCsr ){
    int i;
    for(i=0; i<pCsr->nSegment; i++){
      sqlite3Fts3SegReaderFree(pCsr->apSegment[i]);
    }
    sqlite3_free(pCsr->apSegment);
................................................................................
** currently present in the database.
**
** If this function is called with iLevel<0, but there is only one
** segment in the database, SQLITE_DONE is returned immediately. 
** Otherwise, if successful, SQLITE_OK is returned. If an error occurs, 
** an SQLite error code is returned.
*/
static int fts3SegmentMerge(Fts3Table *p, int iLevel){
  int rc;                         /* Return code */
  int iIdx = 0;                   /* Index of new segment */
  int iNewLevel = 0;              /* Level to create new segment at */
  SegmentWriter *pWriter = 0;     /* Used to write the new, merged, segment */
  Fts3SegFilter filter;           /* Segment term filter condition */
  Fts3SegReaderCursor csr;        /* Cursor to iterate through level(s) */









  rc = sqlite3Fts3SegReaderCursor(p, iLevel, 0, 0, 1, 0, &csr);
  if( rc!=SQLITE_OK || csr.nSegment==0 ) goto finished;

  if( iLevel==FTS3_SEGCURSOR_ALL ){
    /* This call is to merge all segments in the database to a single
    ** segment. The level of the new segment is equal to the the numerically 
    ** greatest segment level currently present in the database. The index
    ** of the new segment is always 0.  */
    int nDummy; /* TODO: Remove this */
    if( csr.nSegment==1 ){
      rc = SQLITE_DONE;
      goto finished;
    }
    rc = fts3SegmentCountMax(p, &nDummy, &iNewLevel);





  }else{
    /* This call is to merge all segments at level iLevel. Find the next
    ** available segment index at level iLevel+1. The call to
    ** fts3AllocateSegdirIdx() will merge the segments at level iLevel+1 to 
    ** a single iLevel+2 segment if necessary.  */
    iNewLevel = iLevel+1;
    rc = fts3AllocateSegdirIdx(p, iNewLevel, &iIdx);
  }
  if( rc!=SQLITE_OK ) goto finished;
  assert( csr.nSegment>0 );
  assert( iNewLevel>=0 );


  memset(&filter, 0, sizeof(Fts3SegFilter));
  filter.flags = FTS3_SEGMENT_REQUIRE_POS;
  filter.flags |= (iLevel==FTS3_SEGCURSOR_ALL ? FTS3_SEGMENT_IGNORE_EMPTY : 0);

  rc = sqlite3Fts3SegReaderStart(p, &csr, &filter);
  while( SQLITE_OK==rc ){
    rc = sqlite3Fts3SegReaderStep(p, &csr);
    if( rc!=SQLITE_ROW ) break;
    rc = fts3SegWriterAdd(p, &pWriter, 1, 
        csr.zTerm, csr.nTerm, csr.aDoclist, csr.nDoclist);
  }
  if( rc!=SQLITE_OK ) goto finished;
  assert( pWriter );


  rc = fts3DeleteSegdir(p, iLevel, csr.apSegment, csr.nSegment);
  if( rc!=SQLITE_OK ) goto finished;

  rc = fts3SegWriterFlush(p, pWriter, iNewLevel, iIdx);

 finished:
  fts3SegWriterFree(pWriter);
  sqlite3Fts3SegReaderFinish(&csr);
  return rc;
}


/* 
** Flush the contents of pendingTerms to a level 0 segment.
*/
SQLITE_PRIVATE int sqlite3Fts3PendingTermsFlush(Fts3Table *p){



  return fts3SegmentMerge(p, FTS3_SEGCURSOR_PENDING);




}

/*
** Encode N integers as varints into a blob.
*/
static void fts3EncodeIntArray(
  int N,             /* The number of integers to encode */
................................................................................
    return;
  }
  sqlite3_bind_blob(pStmt, 1, pBlob, nBlob, SQLITE_STATIC);
  sqlite3_step(pStmt);
  *pRC = sqlite3_reset(pStmt);
  sqlite3_free(a);
}


















/*
** Handle a 'special' INSERT of the form:
**
**   "INSERT INTO tbl(tbl) VALUES(<expr>)"
**
** Argument pVal contains the result of <expr>. Currently the only 
................................................................................
  int rc;                         /* Return Code */
  const char *zVal = (const char *)sqlite3_value_text(pVal);
  int nVal = sqlite3_value_bytes(pVal);

  if( !zVal ){
    return SQLITE_NOMEM;
  }else if( nVal==8 && 0==sqlite3_strnicmp(zVal, "optimize", 8) ){
    rc = fts3SegmentMerge(p, FTS3_SEGCURSOR_ALL);
    if( rc==SQLITE_DONE ){
      rc = SQLITE_OK;
    }else{
      sqlite3Fts3PendingTermsClear(p);
    }
#ifdef SQLITE_TEST
  }else if( nVal>9 && 0==sqlite3_strnicmp(zVal, "nodesize=", 9) ){
    p->nNodeSize = atoi(&zVal[9]);
    rc = SQLITE_OK;
  }else if( nVal>11 && 0==sqlite3_strnicmp(zVal, "maxpending=", 9) ){
    p->nMaxPendingData = atoi(&zVal[11]);
    rc = SQLITE_OK;
#endif
  }else{
    rc = SQLITE_ERROR;
  }

  sqlite3Fts3SegmentsClose(p);
  return rc;
}

/*
** Return the deferred doclist associated with deferred token pDeferred.
** This function assumes that sqlite3Fts3CacheDeferredDoclists() has already
** been called to allocate and populate the doclist.
*/
SQLITE_PRIVATE char *sqlite3Fts3DeferredDoclist(Fts3DeferredToken *pDeferred, int *pnByte){
  if( pDeferred->pList ){
    *pnByte = pDeferred->pList->nData;
    return pDeferred->pList->aData;
  }
  *pnByte = 0;
  return 0;
}

/*
** Helper fucntion for FreeDeferredDoclists(). This function removes all
** references to deferred doclists from within the tree of Fts3Expr 
** structures headed by 
*/
static void fts3DeferredDoclistClear(Fts3Expr *pExpr){
  if( pExpr ){
    fts3DeferredDoclistClear(pExpr->pLeft);
    fts3DeferredDoclistClear(pExpr->pRight);
    if( pExpr->isLoaded ){
      sqlite3_free(pExpr->aDoclist);
      pExpr->isLoaded = 0;
      pExpr->aDoclist = 0;
      pExpr->nDoclist = 0;
      pExpr->pCurrent = 0;
      pExpr->iCurrent = 0;
    }
  }
}

/*
** Delete all cached deferred doclists. Deferred doclists are cached
** (allocated) by the sqlite3Fts3CacheDeferredDoclists() function.
*/
SQLITE_PRIVATE void sqlite3Fts3FreeDeferredDoclists(Fts3Cursor *pCsr){
  Fts3DeferredToken *pDef;
  for(pDef=pCsr->pDeferred; pDef; pDef=pDef->pNext){
    sqlite3_free(pDef->pList);
    pDef->pList = 0;
  }
  if( pCsr->pDeferred ){
    fts3DeferredDoclistClear(pCsr->pExpr);
  }
}

/*
** Free all entries in the pCsr->pDeffered list. Entries are added to 
** this list using sqlite3Fts3DeferToken().
*/
SQLITE_PRIVATE void sqlite3Fts3FreeDeferredTokens(Fts3Cursor *pCsr){
  Fts3DeferredToken *pDef;
  Fts3DeferredToken *pNext;
  for(pDef=pCsr->pDeferred; pDef; pDef=pNext){
    pNext = pDef->pNext;
    sqlite3_free(pDef->pList);
    sqlite3_free(pDef);
  }
  pCsr->pDeferred = 0;
}

/*
** Generate deferred-doclists for all tokens in the pCsr->pDeferred list
................................................................................
        rc = fts3PendingListAppendVarint(&pDef->pList, 0);
      }
    }
  }

  return rc;
}




























/*
** Add an entry for token pToken to the pCsr->pDeferred list.
*/
SQLITE_PRIVATE int sqlite3Fts3DeferToken(
  Fts3Cursor *pCsr,               /* Fts3 table cursor */
  Fts3PhraseToken *pToken,        /* Token to defer */
................................................................................
  sqlite3_value **apVal,          /* Array of arguments */
  sqlite_int64 *pRowid            /* OUT: The affected (or effected) rowid */
){
  Fts3Table *p = (Fts3Table *)pVtab;
  int rc = SQLITE_OK;             /* Return Code */
  int isRemove = 0;               /* True for an UPDATE or DELETE */
  sqlite3_int64 iRemove = 0;      /* Rowid removed by UPDATE or DELETE */
  u32 *aSzIns;                    /* Sizes of inserted documents */
  u32 *aSzDel;                    /* Sizes of deleted documents */
  int nChng = 0;                  /* Net change in number of documents */
  int bInsertDone = 0;

  assert( p->pSegments==0 );

  /* Check for a "special" INSERT operation. One of the form:
................................................................................
  **
  **   INSERT INTO xyz(xyz) VALUES('command');
  */
  if( nArg>1 
   && sqlite3_value_type(apVal[0])==SQLITE_NULL 
   && sqlite3_value_type(apVal[p->nColumn+2])!=SQLITE_NULL 
  ){
    return fts3SpecialInsert(p, apVal[p->nColumn+2]);

  }

  /* Allocate space to hold the change in document sizes */
  aSzIns = sqlite3_malloc( sizeof(aSzIns[0])*(p->nColumn+1)*2 );
  if( aSzIns==0 ) return SQLITE_NOMEM;



  aSzDel = &aSzIns[p->nColumn+1];
  memset(aSzIns, 0, sizeof(aSzIns[0])*(p->nColumn+1)*2);

  /* If this is an INSERT operation, or an UPDATE that modifies the rowid
  ** value, then this operation requires constraint handling.
  **
  ** If the on-conflict mode is REPLACE, this means that the existing row
................................................................................
      }else{
        rc = fts3InsertData(p, apVal, pRowid);
        bInsertDone = 1;
      }
    }
  }
  if( rc!=SQLITE_OK ){
    sqlite3_free(aSzIns);
    return rc;
  }

  /* If this is a DELETE or UPDATE operation, remove the old record. */
  if( sqlite3_value_type(apVal[0])!=SQLITE_NULL ){
    assert( sqlite3_value_type(apVal[0])==SQLITE_INTEGER );
    rc = fts3DeleteByRowid(p, apVal[0], &nChng, aSzDel);
    isRemove = 1;
................................................................................
    nChng++;
  }

  if( p->bHasStat ){
    fts3UpdateDocTotals(&rc, p, aSzIns, aSzDel, nChng);
  }


  sqlite3_free(aSzIns);
  sqlite3Fts3SegmentsClose(p);
  return rc;
}

/* 
** Flush any data in the pending-terms hash table to disk. If successful,
................................................................................
** merge all segments in the database (including the new segment, if 
** there was any data to flush) into a single segment. 
*/
SQLITE_PRIVATE int sqlite3Fts3Optimize(Fts3Table *p){
  int rc;
  rc = sqlite3_exec(p->db, "SAVEPOINT fts3", 0, 0, 0);
  if( rc==SQLITE_OK ){
    rc = fts3SegmentMerge(p, FTS3_SEGCURSOR_ALL);
    if( rc==SQLITE_OK ){
      rc = sqlite3_exec(p->db, "RELEASE fts3", 0, 0, 0);
      if( rc==SQLITE_OK ){
        sqlite3Fts3PendingTermsClear(p);
      }
    }else{
      sqlite3_exec(p->db, "ROLLBACK TO fts3", 0, 0, 0);
      sqlite3_exec(p->db, "RELEASE fts3", 0, 0, 0);
    }
  }
  sqlite3Fts3SegmentsClose(p);
  return rc;
................................................................................
  int (*x)(Fts3Expr*,int,void*),  /* Callback function to invoke for phrases */
  void *pCtx                      /* Second argument to pass to callback */
){
  int iPhrase = 0;                /* Variable used as the phrase counter */
  return fts3ExprIterate2(pExpr, &iPhrase, x, pCtx);
}

/*
** The argument to this function is always a phrase node. Its doclist 
** (Fts3Expr.aDoclist[]) and the doclists associated with all phrase nodes
** to the left of this one in the query tree have already been loaded.
**
** If this phrase node is part of a series of phrase nodes joined by 
** NEAR operators (and is not the left-most of said series), then elements are
** removed from the phrases doclist consistent with the NEAR restriction. If
** required, elements may be removed from the doclists of phrases to the
** left of this one that are part of the same series of NEAR operator 
** connected phrases.
**
** If an OOM error occurs, SQLITE_NOMEM is returned. Otherwise, SQLITE_OK.
*/
static int fts3ExprNearTrim(Fts3Expr *pExpr){
  int rc = SQLITE_OK;
  Fts3Expr *pParent = pExpr->pParent;

  assert( pExpr->eType==FTSQUERY_PHRASE );
  while( rc==SQLITE_OK
   && pParent 
   && pParent->eType==FTSQUERY_NEAR 
   && pParent->pRight==pExpr 
  ){
    /* This expression (pExpr) is the right-hand-side of a NEAR operator. 
    ** Find the expression to the left of the same operator.
    */
    int nNear = pParent->nNear;
    Fts3Expr *pLeft = pParent->pLeft;

    if( pLeft->eType!=FTSQUERY_PHRASE ){
      assert( pLeft->eType==FTSQUERY_NEAR );
      assert( pLeft->pRight->eType==FTSQUERY_PHRASE );
      pLeft = pLeft->pRight;
    }

    rc = sqlite3Fts3ExprNearTrim(pLeft, pExpr, nNear);

    pExpr = pLeft;
    pParent = pExpr->pParent;
  }

  return rc;
}

/*
** This is an fts3ExprIterate() callback used while loading the doclists
** for each phrase into Fts3Expr.aDoclist[]/nDoclist. See also
** fts3ExprLoadDoclists().
*/
static int fts3ExprLoadDoclistsCb(Fts3Expr *pExpr, int iPhrase, void *ctx){
  int rc = SQLITE_OK;

  LoadDoclistCtx *p = (LoadDoclistCtx *)ctx;

  UNUSED_PARAMETER(iPhrase);

  p->nPhrase++;
  p->nToken += pExpr->pPhrase->nToken;

  if( pExpr->isLoaded==0 ){
    rc = sqlite3Fts3ExprLoadDoclist(p->pCsr, pExpr);
    pExpr->isLoaded = 1;
    if( rc==SQLITE_OK ){
      rc = fts3ExprNearTrim(pExpr);
    }
  }

  return rc;
}

/*
** Load the doclists for each phrase in the query associated with FTS3 cursor
** pCsr. 
................................................................................
static int fts3SnippetFindPositions(Fts3Expr *pExpr, int iPhrase, void *ctx){
  SnippetIter *p = (SnippetIter *)ctx;
  SnippetPhrase *pPhrase = &p->aPhrase[iPhrase];
  char *pCsr;

  pPhrase->nToken = pExpr->pPhrase->nToken;

  pCsr = sqlite3Fts3FindPositions(p->pCsr, pExpr, p->pCsr->iPrevId, p->iCol);
  if( pCsr ){
    int iFirst = 0;
    pPhrase->pList = pCsr;
    fts3GetDeltaPosition(&pCsr, &iFirst);
    pPhrase->pHead = pCsr;
    pPhrase->pTail = pCsr;
    pPhrase->iHead = iFirst;
................................................................................
    if( !c ) nEntry++;
  }

  *ppCollist = pEnd;
  return nEntry;
}

static void fts3LoadColumnlistCounts(char **pp, u32 *aOut, int isGlobal){
  char *pCsr = *pp;
  while( *pCsr ){
    int nHit;
    sqlite3_int64 iCol = 0;
    if( *pCsr==0x01 ){
      pCsr++;
      pCsr += sqlite3Fts3GetVarint(pCsr, &iCol);
    }
    nHit = fts3ColumnlistCount(&pCsr);
    assert( nHit>0 );
    if( isGlobal ){
      aOut[iCol*3+1]++;
    }
    aOut[iCol*3] += nHit;
  }
  pCsr++;
  *pp = pCsr;
}

/*
** fts3ExprIterate() callback used to collect the "global" matchinfo stats
** for a single query. 
**
** fts3ExprIterate() callback to load the 'global' elements of a
** FTS3_MATCHINFO_HITS matchinfo array. The global stats are those elements 
** of the matchinfo array that are constant for all rows returned by the 
................................................................................
*/
static int fts3ExprGlobalHitsCb(
  Fts3Expr *pExpr,                /* Phrase expression node */
  int iPhrase,                    /* Phrase number (numbered from zero) */
  void *pCtx                      /* Pointer to MatchInfo structure */
){
  MatchInfo *p = (MatchInfo *)pCtx;
  Fts3Cursor *pCsr = p->pCursor;
  char *pIter;
  char *pEnd;
  char *pFree = 0;
  u32 *aOut = &p->aMatchinfo[3*iPhrase*p->nCol];

  assert( pExpr->isLoaded );
  assert( pExpr->eType==FTSQUERY_PHRASE );

  if( pCsr->pDeferred ){
    Fts3Phrase *pPhrase = pExpr->pPhrase;
    int ii;
    for(ii=0; ii<pPhrase->nToken; ii++){
      if( pPhrase->aToken[ii].bFulltext ) break;
    }
    if( ii<pPhrase->nToken ){
      int nFree = 0;
      int rc = sqlite3Fts3ExprLoadFtDoclist(pCsr, pExpr, &pFree, &nFree);
      if( rc!=SQLITE_OK ) return rc;
      pIter = pFree;
      pEnd = &pFree[nFree];
    }else{
      int iCol;                   /* Column index */
      for(iCol=0; iCol<p->nCol; iCol++){
        aOut[iCol*3 + 1] = (u32)p->nDoc;
        aOut[iCol*3 + 2] = (u32)p->nDoc;
      }
      return SQLITE_OK;
    }
  }else{
    pIter = pExpr->aDoclist;
    pEnd = &pExpr->aDoclist[pExpr->nDoclist];
  }

  /* Fill in the global hit count matrix row for this phrase. */
  while( pIter<pEnd ){
    while( *pIter++ & 0x80 );      /* Skip past docid. */
    fts3LoadColumnlistCounts(&pIter, &aOut[1], 1);
  }

  sqlite3_free(pFree);
  return SQLITE_OK;

}

/*
** fts3ExprIterate() callback used to collect the "local" part of the
** FTS3_MATCHINFO_HITS array. The local stats are those elements of the 
** array that are different for each row returned by the query.
*/
................................................................................
  int iPhrase,                    /* Phrase number */
  void *pCtx                      /* Pointer to MatchInfo structure */
){
  MatchInfo *p = (MatchInfo *)pCtx;
  int iStart = iPhrase * p->nCol * 3;
  int i;

  for(i=0; i<p->nCol; i++) p->aMatchinfo[iStart+i*3] = 0;

  if( pExpr->aDoclist ){
    char *pCsr;

    pCsr = sqlite3Fts3FindPositions(p->pCursor, pExpr, p->pCursor->iPrevId, -1);
    if( pCsr ){
      fts3LoadColumnlistCounts(&pCsr, &p->aMatchinfo[iStart], 0);
    }
  }

  return SQLITE_OK;
}

static int fts3MatchinfoCheck(
................................................................................
** iterating through a multi-column position-list corresponding to the
** hits for a single phrase on a single row in order to calculate the
** values for a matchinfo() FTS3_MATCHINFO_LCS request.
*/
typedef struct LcsIterator LcsIterator;
struct LcsIterator {
  Fts3Expr *pExpr;                /* Pointer to phrase expression */
  char *pRead;                    /* Cursor used to iterate through aDoclist */
  int iPosOffset;                 /* Tokens count up to end of this phrase */
  int iCol;                       /* Current column number */

  int iPos;                       /* Current position */
};

/* 
** If LcsIterator.iCol is set to the following value, the iterator has
** finished iterating through all offsets for all columns.
*/
................................................................................
*/
static int fts3LcsIteratorAdvance(LcsIterator *pIter){
  char *pRead = pIter->pRead;
  sqlite3_int64 iRead;
  int rc = 0;

  pRead += sqlite3Fts3GetVarint(pRead, &iRead);
  if( iRead==0 ){
    pIter->iCol = LCS_ITERATOR_FINISHED;
    rc = 1;
  }else{
    if( iRead==1 ){
      pRead += sqlite3Fts3GetVarint(pRead, &iRead);
      pIter->iCol = (int)iRead;
      pIter->iPos = pIter->iPosOffset;
      pRead += sqlite3Fts3GetVarint(pRead, &iRead);
      rc = 1;
    }
    pIter->iPos += (int)(iRead-2);
  }

  pIter->pRead = pRead;
  return rc;
}
  
................................................................................
  /* Allocate and populate the array of LcsIterator objects. The array
  ** contains one element for each matchable phrase in the query.
  **/
  aIter = sqlite3_malloc(sizeof(LcsIterator) * pCsr->nPhrase);
  if( !aIter ) return SQLITE_NOMEM;
  memset(aIter, 0, sizeof(LcsIterator) * pCsr->nPhrase);
  (void)fts3ExprIterate(pCsr->pExpr, fts3MatchinfoLcsCb, (void*)aIter);

  for(i=0; i<pInfo->nPhrase; i++){
    LcsIterator *pIter = &aIter[i];
    nToken -= pIter->pExpr->pPhrase->nToken;
    pIter->iPosOffset = nToken;
    pIter->pRead = sqlite3Fts3FindPositions(pCsr,pIter->pExpr,pCsr->iPrevId,-1);
    if( pIter->pRead ){
      pIter->iPos = pIter->iPosOffset;
      fts3LcsIteratorAdvance(&aIter[i]);
    }else{
      pIter->iCol = LCS_ITERATOR_FINISHED;
    }
  }

  for(iCol=0; iCol<pInfo->nCol; iCol++){
    int nLcs = 0;                 /* LCS value for this column */
    int nLive = 0;                /* Number of iterators in aIter not at EOF */

    /* Loop through the iterators in aIter[]. Set nLive to the number of
    ** iterators that point to a position-list corresponding to column iCol.
    */
    for(i=0; i<pInfo->nPhrase; i++){
      assert( aIter[i].iCol>=iCol );
      if( aIter[i].iCol==iCol ) nLive++;
    }

    /* The following loop runs until all iterators in aIter[] have finished
    ** iterating through positions in column iCol. Exactly one of the 
    ** iterators is advanced each time the body of the loop is run.
    */
    while( nLive>0 ){
      LcsIterator *pAdv = 0;      /* The iterator to advance by one position */
      int nThisLcs = 0;           /* LCS for the current iterator positions */

      for(i=0; i<pInfo->nPhrase; i++){
        LcsIterator *pIter = &aIter[i];
        if( iCol!=pIter->iCol ){  
          /* This iterator is already at EOF for this column. */
          nThisLcs = 0;
        }else{
          if( pAdv==0 || pIter->iPos<pAdv->iPos ){
            pAdv = pIter;
          }
          if( nThisLcs==0 || pIter->iPos==pIter[-1].iPos ){
................................................................................

      case FTS3_MATCHINFO_NCOL:
        if( bGlobal ) pInfo->aMatchinfo[0] = pInfo->nCol;
        break;
        
      case FTS3_MATCHINFO_NDOC:
        if( bGlobal ){
          sqlite3_int64 nDoc;
          rc = fts3MatchinfoSelectDoctotal(pTab, &pSelect, &nDoc, 0);
          pInfo->aMatchinfo[0] = (u32)nDoc;
        }
        break;

      case FTS3_MATCHINFO_AVGLENGTH: 
        if( bGlobal ){
................................................................................
  TermOffsetCtx *p = (TermOffsetCtx *)ctx;
  int nTerm;                      /* Number of tokens in phrase */
  int iTerm;                      /* For looping through nTerm phrase terms */
  char *pList;                    /* Pointer to position list for phrase */
  int iPos = 0;                   /* First position in position-list */

  UNUSED_PARAMETER(iPhrase);
  pList = sqlite3Fts3FindPositions(p->pCsr, pExpr, p->iDocid, p->iCol);
  nTerm = pExpr->pPhrase->nToken;
  if( pList ){
    fts3GetDeltaPosition(&pList, &iPos);
    assert( iPos>=0 );
  }

  for(iTerm=0; iTerm<nTerm; iTerm++){
................................................................................
/*
** Return the N-dimensional volumn of the cell stored in *p.
*/
static float cellArea(Rtree *pRtree, RtreeCell *p){
  float area = 1.0;
  int ii;
  for(ii=0; ii<(pRtree->nDim*2); ii+=2){
    area = area * (DCOORD(p->aCoord[ii+1]) - DCOORD(p->aCoord[ii]));
  }
  return area;
}

/*
** Return the margin length of cell p. The margin length is the sum
** of the objects size in each dimension.
*/
static float cellMargin(Rtree *pRtree, RtreeCell *p){
  float margin = 0.0;
  int ii;
  for(ii=0; ii<(pRtree->nDim*2); ii+=2){
    margin += (DCOORD(p->aCoord[ii+1]) - DCOORD(p->aCoord[ii]));
  }
  return margin;
}

/*
** Store the union of cells p1 and p2 in p1.
*/
................................................................................
        x1 = MAX(DCOORD(p->aCoord[jj]), DCOORD(aCell[ii].aCoord[jj]));
        x2 = MIN(DCOORD(p->aCoord[jj+1]), DCOORD(aCell[ii].aCoord[jj+1]));

        if( x2<x1 ){
          o = 0.0;
          break;
        }else{
          o = o * (x2-x1);
        }
      }
      overlap += o;
    }
  }
  return overlap;
}
................................................................................
  Rtree *pRtree, 
  RtreeCell *p, 
  RtreeCell *pInsert, 
  RtreeCell *aCell, 
  int nCell, 
  int iExclude
){
  float before;
  float after;
  before = cellOverlap(pRtree, p, aCell, nCell, iExclude);
  cellUnion(pRtree, p, pInsert);
  after = cellOverlap(pRtree, p, aCell, nCell, iExclude);
  return after-before;
}
#endif


/*
** This function implements the ChooseLeaf algorithm from Gutman[84].
** ChooseSubTree in r*tree terminology.
................................................................................
  int rc;
  int ii;
  RtreeNode *pNode;
  rc = nodeAcquire(pRtree, 1, 0, &pNode);

  for(ii=0; rc==SQLITE_OK && ii<(pRtree->iDepth-iHeight); ii++){
    int iCell;
    sqlite3_int64 iBest;

    float fMinGrowth;
    float fMinArea;
    float fMinOverlap;

    int nCell = NCELL(pNode);
    RtreeCell cell;
    RtreeNode *pChild;

    RtreeCell *aCell = 0;

................................................................................
  RtreeCell *pBboxLeft,
  RtreeCell *pBboxRight
){
  int **aaSorted;
  int *aSpare;
  int ii;

  int iBestDim;
  int iBestSplit;
  float fBestMargin;

  int nByte = (pRtree->nDim+1)*(sizeof(int*)+nCell*sizeof(int));

  aaSorted = (int **)sqlite3_malloc(nByte);
  if( !aaSorted ){
    return SQLITE_NOMEM;
  }
................................................................................
      aaSorted[ii][jj] = jj;
    }
    SortByDimension(pRtree, aaSorted[ii], nCell, ii, aCell, aSpare);
  }

  for(ii=0; ii<pRtree->nDim; ii++){
    float margin = 0.0;
    float fBestOverlap;
    float fBestArea;
    int iBestLeft;
    int nLeft;

    for(
      nLeft=RTREE_MINCELLS(pRtree); 
      nLeft<=(nCell-RTREE_MINCELLS(pRtree)); 
      nLeft++
    ){
................................................................................
}

static int deleteCell(Rtree *, RtreeNode *, int, int);

static int removeNode(Rtree *pRtree, RtreeNode *pNode, int iHeight){
  int rc;
  int rc2;
  RtreeNode *pParent;
  int iCell;

  assert( pNode->nRef==1 );

  /* Remove the entry in the parent cell. */
  rc = nodeParentIndex(pRtree, pNode, &iCell);
  if( rc==SQLITE_OK ){
................................................................................
    if( ii==(nCell-1) ){
      memcpy(&aCell[ii], pCell, sizeof(RtreeCell));
    }else{
      nodeGetCell(pRtree, pNode, ii, &aCell[ii]);
    }
    aOrder[ii] = ii;
    for(iDim=0; iDim<pRtree->nDim; iDim++){
      aCenterCoord[iDim] += DCOORD(aCell[ii].aCoord[iDim*2]);
      aCenterCoord[iDim] += DCOORD(aCell[ii].aCoord[iDim*2+1]);
    }
  }
  for(iDim=0; iDim<pRtree->nDim; iDim++){
    aCenterCoord[iDim] = aCenterCoord[iDim]/((float)nCell*2.0);
  }

  for(ii=0; ii<nCell; ii++){
    aDistance[ii] = 0.0;
    for(iDim=0; iDim<pRtree->nDim; iDim++){
      float coord = DCOORD(aCell[ii].aCoord[iDim*2+1]) - 
          DCOORD(aCell[ii].aCoord[iDim*2]);
      aDistance[ii] += (coord-aCenterCoord[iDim])*(coord-aCenterCoord[iDim]);
    }
  }

  SortByDistance(aOrder, nCell, aDistance, aSpare);
  nodeZero(pRtree, pNode);

................................................................................
    RtreeNode *pInsert;
    RtreeCell cell;
    nodeGetCell(pRtree, pNode, ii, &cell);

    /* Find a node to store this cell in. pNode->iNode currently contains
    ** the height of the sub-tree headed by the cell.
    */
    rc = ChooseLeaf(pRtree, &cell, pNode->iNode, &pInsert);
    if( rc==SQLITE_OK ){
      int rc2;
      rc = rtreeInsertCell(pRtree, pInsert, &cell, pNode->iNode);
      rc2 = nodeRelease(pRtree, pInsert);
      if( rc==SQLITE_OK ){
        rc = rc2;
      }
    }
  }
  return rc;
................................................................................
  sqlite3 *db,                    /* Database handle */
  Rtree *pRtree,                  /* Rtree handle */
  int isCreate                    /* True for xCreate, false for xConnect */
){
  int rc;
  char *zSql;
  if( isCreate ){
    int iPageSize;
    zSql = sqlite3_mprintf("PRAGMA %Q.page_size", pRtree->zDb);
    rc = getIntFromStmt(db, zSql, &iPageSize);
    if( rc==SQLITE_OK ){
      pRtree->iNodeSize = iPageSize-64;
      if( (4+pRtree->nBytesPerCell*RTREE_MAXCELLS)<pRtree->iNodeSize ){
        pRtree->iNodeSize = 4+pRtree->nBytesPerCell*RTREE_MAXCELLS;
      }
................................................................................
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file implements a tokenizer for fts3 based on the ICU library.
** 
** $Id: fts3_icu.c,v 1.3 2008/09/01 18:34:20 danielk1977 Exp $
*/

#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
#ifdef SQLITE_ENABLE_ICU


#include <unicode/ubrk.h>
#include <unicode/utf16.h>

**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.7.7"
#define SQLITE_VERSION_NUMBER 3007007
#define SQLITE_SOURCE_ID      "2011-06-23 17:29:33 b61a76a53af04f731fe7617f7b6b4fb2aef6587b"

/*
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version, sqlite3_sourceid
**
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
................................................................................
**
** ^The sqlite3_exec() interface runs zero or more UTF-8 encoded,
** semicolon-separate SQL statements passed into its 2nd argument,
** in the context of the [database connection] passed in as its 1st
** argument.  ^If the callback function of the 3rd argument to
** sqlite3_exec() is not NULL, then it is invoked for each result row
** coming out of the evaluated SQL statements.  ^The 4th argument to
** sqlite3_exec() is relayed through to the 1st argument of each
** callback invocation.  ^If the callback pointer to sqlite3_exec()
** is NULL, then no callback is ever invoked and result rows are
** ignored.
**
** ^If an error occurs while evaluating the SQL statements passed into
** sqlite3_exec(), then execution of the current statement stops and
** subsequent statements are skipped.  ^If the 5th parameter to sqlite3_exec()
................................................................................
#define SQLITE_IOERR_SHMLOCK           (SQLITE_IOERR | (20<<8))
#define SQLITE_IOERR_SHMMAP            (SQLITE_IOERR | (21<<8))
#define SQLITE_IOERR_SEEK              (SQLITE_IOERR | (22<<8))
#define SQLITE_LOCKED_SHAREDCACHE      (SQLITE_LOCKED |  (1<<8))
#define SQLITE_BUSY_RECOVERY           (SQLITE_BUSY   |  (1<<8))
#define SQLITE_CANTOPEN_NOTEMPDIR      (SQLITE_CANTOPEN | (1<<8))
#define SQLITE_CORRUPT_VTAB            (SQLITE_CORRUPT | (1<<8))
#define SQLITE_READONLY_RECOVERY       (SQLITE_READONLY | (1<<8))
#define SQLITE_READONLY_CANTLOCK       (SQLITE_READONLY | (2<<8))

/*
** CAPI3REF: Flags For File Open Operations
**
** These bit values are intended for use in the
** 3rd parameter to the [sqlite3_open_v2()] interface and
** in the 4th parameter to the [sqlite3_vfs.xOpen] method.
................................................................................
** of good-quality randomness into zOut.  The return value is
** the actual number of bytes of randomness obtained.
** The xSleep() method causes the calling thread to sleep for at
** least the number of microseconds given.  ^The xCurrentTime()
** method returns a Julian Day Number for the current date and time as
** a floating point value.
** ^The xCurrentTimeInt64() method returns, as an integer, the Julian
** Day Number multiplied by 86400000 (the number of milliseconds in 
** a 24-hour day).  
** ^SQLite will use the xCurrentTimeInt64() method to get the current
** date and time if that method is available (if iVersion is 2 or 
** greater and the function pointer is not NULL) and will fall back
** to xCurrentTime() if xCurrentTimeInt64() is unavailable.
**
** ^The xSetSystemCall(), xGetSystemCall(), and xNestSystemCall() interfaces
................................................................................
** ^SQLite will never require a scratch buffer that is more than 6
** times the database page size. ^If SQLite needs needs additional
** scratch memory beyond what is provided by this configuration option, then 
** [sqlite3_malloc()] will be used to obtain the memory needed.</dd>
**
** [[SQLITE_CONFIG_PAGECACHE]] <dt>SQLITE_CONFIG_PAGECACHE</dt>
** <dd> ^This option specifies a static memory buffer that SQLite can use for
** the database page cache with the default page cache implementation.  
** This configuration should not be used if an application-define page
** cache implementation is loaded using the SQLITE_CONFIG_PCACHE option.
** There are three arguments to this option: A pointer to 8-byte aligned
** memory, the size of each page buffer (sz), and the number of pages (N).
** The sz argument should be the size of the largest database page
** (a power of two between 512 and 32768) plus a little extra for each
** page header.  ^The page header size is 20 to 40 bytes depending on
................................................................................
** automatically deleted as soon as the database connection is closed.
**
** [[URI filenames in sqlite3_open()]] <h3>URI Filenames</h3>
**
** ^If [URI filename] interpretation is enabled, and the filename argument
** begins with "file:", then the filename is interpreted as a URI. ^URI
** filename interpretation is enabled if the [SQLITE_OPEN_URI] flag is
** set in the fourth argument to sqlite3_open_v2(), or if it has
** been enabled globally using the [SQLITE_CONFIG_URI] option with the
** [sqlite3_config()] method or by the [SQLITE_USE_URI] compile-time option.
** As of SQLite version 3.7.7, URI filename interpretation is turned off
** by default, but future releases of SQLite might enable URI filename
** interpretation by default.  See "[URI filenames]" for additional
** information.
**
** URI filenames are parsed according to RFC 3986. ^If the URI contains an
** authority, then it must be either an empty string or the string 
** "localhost". ^If the authority is not an empty string or "localhost", an 
** error is returned to the caller. ^The fragment component of a URI, if 
** present, is ignored.
................................................................................
** [SQLITE_DONE], [SQLITE_ROW], [SQLITE_ERROR], or [SQLITE_MISUSE].
** ^With the "v2" interface, any of the other [result codes] or
** [extended result codes] might be returned as well.
**
** ^[SQLITE_BUSY] means that the database engine was unable to acquire the
** database locks it needs to do its job.  ^If the statement is a [COMMIT]
** or occurs outside of an explicit transaction, then you can retry the
** statement.  If the statement is not a [COMMIT] and occurs within an
** explicit transaction then you should rollback the transaction before
** continuing.
**
** ^[SQLITE_DONE] means that the statement has finished executing
** successfully.  sqlite3_step() should not be called again on this virtual
** machine without first calling [sqlite3_reset()] to reset the virtual
** machine back to its initial state.
................................................................................
SQLITE_API int sqlite3_column_type(sqlite3_stmt*, int iCol);
SQLITE_API sqlite3_value *sqlite3_column_value(sqlite3_stmt*, int iCol);

/*
** CAPI3REF: Destroy A Prepared Statement Object
**
** ^The sqlite3_finalize() function is called to delete a [prepared statement].
** ^If the most recent evaluation of the statement encountered no errors
** or if the statement is never been evaluated, then sqlite3_finalize() returns
** SQLITE_OK.  ^If the most recent evaluation of statement S failed, then
** sqlite3_finalize(S) returns the appropriate [error code] or
** [extended error code].
**
** ^The sqlite3_finalize(S) routine can be called at any point during
** the life cycle of [prepared statement] S:
................................................................................
** ^The implementation is not required to provided versions of these
** routines that actually work. If the implementation does not provide working
** versions of these routines, it should at least provide stubs that always
** return true so that one does not get spurious assertion failures.
**
** ^If the argument to sqlite3_mutex_held() is a NULL pointer then
** the routine should return 1.   This seems counter-intuitive since
** clearly the mutex cannot be held if it does not exist.  But
** the reason the mutex does not exist is because the build is not
** using mutexes.  And we do not want the assert() containing the
** call to sqlite3_mutex_held() to fail, so a non-zero return is
** the appropriate thing to do.  ^The sqlite3_mutex_notheld()
** interface should also return 1 when given a NULL pointer.
*/
#ifndef NDEBUG
................................................................................
#define SQLITE_TESTCTRL_ASSERT                  12
#define SQLITE_TESTCTRL_ALWAYS                  13
#define SQLITE_TESTCTRL_RESERVE                 14
#define SQLITE_TESTCTRL_OPTIMIZATIONS           15
#define SQLITE_TESTCTRL_ISKEYWORD               16
#define SQLITE_TESTCTRL_PGHDRSZ                 17
#define SQLITE_TESTCTRL_SCRATCHMALLOC           18
#define SQLITE_TESTCTRL_LOCALTIME_FAULT         19
#define SQLITE_TESTCTRL_LAST                    19

/*
** CAPI3REF: SQLite Runtime Status
**
** ^This interface is used to retrieve runtime status information
** about the performance of SQLite, and optionally to reset various
** highwater marks.  ^The first argument is an integer code for
................................................................................
** stored in the cache, both pinned and unpinned.
** 
** [[the xFetch() page cache methods]]
** The xFetch() method locates a page in the cache and returns a pointer to 
** the page, or a NULL pointer.
** A "page", in this context, means a buffer of szPage bytes aligned at an
** 8-byte boundary. The page to be fetched is determined by the key. ^The
** minimum key value is 1.  After it has been retrieved using xFetch, the page 
** is considered to be "pinned".
**
** If the requested page is already in the page cache, then the page cache
** implementation must return a pointer to the page buffer with its content
** intact.  If the requested page is not already in the cache, then the
** cache implementation should use the value of the createFlag
** parameter to help it determined what action to take:
................................................................................
SQLITE_PRIVATE int sqlite3VdbeAddOp0(Vdbe*,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp1(Vdbe*,int,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp2(Vdbe*,int,int,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp3(Vdbe*,int,int,int,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp4(Vdbe*,int,int,int,int,const char *zP4,int);
SQLITE_PRIVATE int sqlite3VdbeAddOp4Int(Vdbe*,int,int,int,int,int);
SQLITE_PRIVATE int sqlite3VdbeAddOpList(Vdbe*, int nOp, VdbeOpList const *aOp);
SQLITE_PRIVATE void sqlite3VdbeAddParseSchemaOp(Vdbe*,int,char*);
SQLITE_PRIVATE void sqlite3VdbeChangeP1(Vdbe*, int addr, int P1);
SQLITE_PRIVATE void sqlite3VdbeChangeP2(Vdbe*, int addr, int P2);
SQLITE_PRIVATE void sqlite3VdbeChangeP3(Vdbe*, int addr, int P3);
SQLITE_PRIVATE void sqlite3VdbeChangeP5(Vdbe*, u8 P5);
SQLITE_PRIVATE void sqlite3VdbeJumpHere(Vdbe*, int addr);
SQLITE_PRIVATE void sqlite3VdbeChangeToNoop(Vdbe*, int addr, int N);
SQLITE_PRIVATE void sqlite3VdbeChangeP4(Vdbe*, int addr, const char *zP4, int N);
SQLITE_PRIVATE void sqlite3VdbeUsesBtree(Vdbe*, int);
SQLITE_PRIVATE VdbeOp *sqlite3VdbeGetOp(Vdbe*, int);
SQLITE_PRIVATE int sqlite3VdbeMakeLabel(Vdbe*);
SQLITE_PRIVATE void sqlite3VdbeRunOnlyOnce(Vdbe*);
SQLITE_PRIVATE void sqlite3VdbeDelete(Vdbe*);
SQLITE_PRIVATE void sqlite3VdbeDeleteObject(sqlite3*,Vdbe*);
SQLITE_PRIVATE void sqlite3VdbeMakeReady(Vdbe*,Parse*);
SQLITE_PRIVATE int sqlite3VdbeFinalize(Vdbe*);
SQLITE_PRIVATE void sqlite3VdbeResolveLabel(Vdbe*, int);
SQLITE_PRIVATE int sqlite3VdbeCurrentAddr(Vdbe*);
#ifdef SQLITE_DEBUG
SQLITE_PRIVATE   int sqlite3VdbeAssertMayAbort(Vdbe *, int);
SQLITE_PRIVATE   void sqlite3VdbeTrace(Vdbe*,FILE*);
#endif
SQLITE_PRIVATE void sqlite3VdbeResetStepResult(Vdbe*);
SQLITE_PRIVATE void sqlite3VdbeRewind(Vdbe*);
SQLITE_PRIVATE int sqlite3VdbeReset(Vdbe*);
SQLITE_PRIVATE void sqlite3VdbeSetNumCols(Vdbe*,int);
SQLITE_PRIVATE int sqlite3VdbeSetColName(Vdbe*, int, int, const char *, void(*)(void*));
SQLITE_PRIVATE void sqlite3VdbeCountChanges(Vdbe*);
SQLITE_PRIVATE sqlite3 *sqlite3VdbeDb(Vdbe*);
SQLITE_PRIVATE void sqlite3VdbeSetSql(Vdbe*, const char *z, int n, int);
SQLITE_PRIVATE void sqlite3VdbeSwap(Vdbe*,Vdbe*);
................................................................................
** Schema objects are automatically deallocated when the last Btree that
** references them is destroyed.   The TEMP Schema is manually freed by
** sqlite3_close().
*
** A thread must be holding a mutex on the corresponding Btree in order
** to access Schema content.  This implies that the thread must also be
** holding a mutex on the sqlite3 connection pointer that owns the Btree.
** For a TEMP Schema, only the connection mutex is required.
*/
struct Schema {
  int schema_cookie;   /* Database schema version number for this file */
  int iGeneration;     /* Generation counter.  Incremented with each change */
  Hash tblHash;        /* All tables indexed by name */
  Hash idxHash;        /* All (named) indices indexed by name */
  Hash trigHash;       /* All triggers indexed by name */
................................................................................
#define SQLITE_QueryFlattener 0x01        /* Disable query flattening */
#define SQLITE_ColumnCache    0x02        /* Disable the column cache */
#define SQLITE_IndexSort      0x04        /* Disable indexes for sorting */
#define SQLITE_IndexSearch    0x08        /* Disable indexes for searching */
#define SQLITE_IndexCover     0x10        /* Disable index covering table */
#define SQLITE_GroupByOrder   0x20        /* Disable GROUPBY cover of ORDERBY */
#define SQLITE_FactorOutConst 0x40        /* Disable factoring out constants */
#define SQLITE_IdxRealAsInt   0x80        /* Store REAL as INT in indices */
#define SQLITE_OptMask        0xff        /* Mask of all disablable opts */

/*
** Possible values for the sqlite.magic field.
** The numbers are obtained at random and have no special meaning, other
** than being distinct from one another.
*/
................................................................................
  u8 disableTriggers;  /* True to disable triggers */
  double nQueryLoop;   /* Estimated number of iterations of a query */

  /* Above is constant between recursions.  Below is reset before and after
  ** each recursion */

  int nVar;            /* Number of '?' variables seen in the SQL so far */
  int nzVar;           /* Number of available slots in azVar[] */
  char **azVar;        /* Pointers to names of parameters */

  Vdbe *pReprepare;    /* VM being reprepared (sqlite3Reprepare()) */
  int nAlias;          /* Number of aliased result set columns */
  int nAliasAlloc;     /* Number of allocated slots for aAlias[] */
  int *aAlias;         /* Register used to hold aliased result */
  u8 explain;          /* True if the EXPLAIN flag is found on the query */
  Token sNameToken;    /* Token with unqualified schema object name */
  Token sLastToken;    /* The last token parsed */
................................................................................
  int isMutexInit;                  /* True after mutexes are initialized */
  int isMallocInit;                 /* True after malloc is initialized */
  int isPCacheInit;                 /* True after malloc is initialized */
  sqlite3_mutex *pInitMutex;        /* Mutex used by sqlite3_initialize() */
  int nRefInitMutex;                /* Number of users of pInitMutex */
  void (*xLog)(void*,int,const char*); /* Function for logging */
  void *pLogArg;                       /* First argument to xLog() */
  int bLocaltimeFault;              /* True to fail localtime() calls */
};

/*
** Context pointer passed down through the tree-walk.
*/
struct Walker {
  int (*xExprCallback)(Walker*, Expr*);     /* Callback for expressions */
................................................................................
SQLITE_PRIVATE int sqlite3FixExprList(DbFixer*, ExprList*);
SQLITE_PRIVATE int sqlite3FixTriggerStep(DbFixer*, TriggerStep*);
SQLITE_PRIVATE int sqlite3AtoF(const char *z, double*, int, u8);
SQLITE_PRIVATE int sqlite3GetInt32(const char *, int*);
SQLITE_PRIVATE int sqlite3Atoi(const char*);
SQLITE_PRIVATE int sqlite3Utf16ByteLen(const void *pData, int nChar);
SQLITE_PRIVATE int sqlite3Utf8CharLen(const char *pData, int nByte);
SQLITE_PRIVATE u32 sqlite3Utf8Read(const u8*, const u8**);

/*
** Routines to read and write variable-length integers.  These used to
** be defined locally, but now we use the varint routines in the util.c
** file.  Code should use the MACRO forms below, as the Varint32 versions
** are coded to assume the single byte case is already handled (which 
** the MACRO form does).
................................................................................
   0,                         /* isMutexInit */
   0,                         /* isMallocInit */
   0,                         /* isPCacheInit */
   0,                         /* pInitMutex */
   0,                         /* nRefInitMutex */
   0,                         /* xLog */
   0,                         /* pLogArg */
   0,                         /* bLocaltimeFault */
};


/*
** Hash table for global functions - functions common to all
** database connections.  After initialization, this table is
** read-only.
................................................................................
  u32 magic;              /* Magic number for sanity checking */
  char *zErrMsg;          /* Error message written here */
  Vdbe *pPrev,*pNext;     /* Linked list of VDBEs with the same Vdbe.db */
  VdbeCursor **apCsr;     /* One element of this array for each open cursor */
  Mem *aVar;              /* Values for the OP_Variable opcode. */
  char **azVar;           /* Name of variables */
  ynVar nVar;             /* Number of entries in aVar[] */
  ynVar nzVar;            /* Number of entries in azVar[] */
  u32 cacheCtr;           /* VdbeCursor row cache generation counter */
  int pc;                 /* The program counter */
  int rc;                 /* Value to return */
  u8 errorAction;         /* Recovery action to do in case of an error */

  u8 explain;             /* True if EXPLAIN present on SQL command */
  u8 changeCntOn;         /* True to update the change-counter */
  u8 expired;             /* True if the VM needs to be recompiled */
  u8 runOnlyOnce;         /* Automatically expire on reset */
  u8 minWriteFileFormat;  /* Minimum file format for writable database files */
  u8 inVtabMethod;        /* See comments above */
  u8 usesStmtJournal;     /* True if uses a statement journal */
................................................................................
**      Willmann-Bell, Inc
**      Richmond, Virginia (USA)
*/
#include <time.h>

#ifndef SQLITE_OMIT_DATETIME_FUNCS


















/*
** A structure for holding a single date and time.
*/
typedef struct DateTime DateTime;
struct DateTime {
  sqlite3_int64 iJD; /* The julian day number times 86400000 */
................................................................................
** Clear the YMD and HMS and the TZ
*/
static void clearYMD_HMS_TZ(DateTime *p){
  p->validYMD = 0;
  p->validHMS = 0;
  p->validTZ = 0;
}

/*
** On recent Windows platforms, the localtime_s() function is available
** as part of the "Secure CRT". It is essentially equivalent to 
** localtime_r() available under most POSIX platforms, except that the 
** order of the parameters is reversed.
**
** See http://msdn.microsoft.com/en-us/library/a442x3ye(VS.80).aspx.
**
** If the user has not indicated to use localtime_r() or localtime_s()
** already, check for an MSVC build environment that provides 
** localtime_s().
*/
#if !defined(HAVE_LOCALTIME_R) && !defined(HAVE_LOCALTIME_S) && \
     defined(_MSC_VER) && defined(_CRT_INSECURE_DEPRECATE)
#define HAVE_LOCALTIME_S 1
#endif

#ifndef SQLITE_OMIT_LOCALTIME
/*
** The following routine implements the rough equivalent of localtime_r()
** using whatever operating-system specific localtime facility that
** is available.  This routine returns 0 on success and
** non-zero on any kind of error.
**
** If the sqlite3GlobalConfig.bLocaltimeFault variable is true then this
** routine will always fail.
*/
static int osLocaltime(time_t *t, struct tm *pTm){
  int rc;
#if (!defined(HAVE_LOCALTIME_R) || !HAVE_LOCALTIME_R) \
      && (!defined(HAVE_LOCALTIME_S) || !HAVE_LOCALTIME_S)
  struct tm *pX;
  sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
  sqlite3_mutex_enter(mutex);
  pX = localtime(t);
#ifndef SQLITE_OMIT_BUILTIN_TEST
  if( sqlite3GlobalConfig.bLocaltimeFault ) pX = 0;
#endif
  if( pX ) *pTm = *pX;
  sqlite3_mutex_leave(mutex);
  rc = pX==0;
#else
#ifndef SQLITE_OMIT_BUILTIN_TEST
  if( sqlite3GlobalConfig.bLocaltimeFault ) return 1;
#endif
#if defined(HAVE_LOCALTIME_R) && HAVE_LOCALTIME_R
  rc = localtime_r(t, pTm)==0;
#else
  rc = localtime_s(pTm, t);
#endif /* HAVE_LOCALTIME_R */
#endif /* HAVE_LOCALTIME_R || HAVE_LOCALTIME_S */
  return rc;
}
#endif /* SQLITE_OMIT_LOCALTIME */


#ifndef SQLITE_OMIT_LOCALTIME
/*
** Compute the difference (in milliseconds) between localtime and UTC

** (a.k.a. GMT) for the time value p where p is in UTC. If no error occurs,
** return this value and set *pRc to SQLITE_OK. 
**
** Or, if an error does occur, set *pRc to SQLITE_ERROR. The returned value
** is undefined in this case.
*/
static sqlite3_int64 localtimeOffset(
  DateTime *p,                    /* Date at which to calculate offset */
  sqlite3_context *pCtx,          /* Write error here if one occurs */
  int *pRc                        /* OUT: Error code. SQLITE_OK or ERROR */
){
  DateTime x, y;
  time_t t;
  struct tm sLocal;

  /* Initialize the contents of sLocal to avoid a compiler warning. */
  memset(&sLocal, 0, sizeof(sLocal));

  x = *p;
  computeYMD_HMS(&x);
  if( x.Y<1971 || x.Y>=2038 ){
    x.Y = 2000;
    x.M = 1;
    x.D = 1;
    x.h = 0;
................................................................................
    int s = (int)(x.s + 0.5);
    x.s = s;
  }
  x.tz = 0;
  x.validJD = 0;
  computeJD(&x);
  t = (time_t)(x.iJD/1000 - 21086676*(i64)10000);



  if( osLocaltime(&t, &sLocal) ){






    sqlite3_result_error(pCtx, "local time unavailable", -1);
    *pRc = SQLITE_ERROR;
    return 0;
  }




  y.Y = sLocal.tm_year + 1900;
  y.M = sLocal.tm_mon + 1;
  y.D = sLocal.tm_mday;
  y.h = sLocal.tm_hour;
  y.m = sLocal.tm_min;
  y.s = sLocal.tm_sec;















  y.validYMD = 1;
  y.validHMS = 1;
  y.validJD = 0;
  y.validTZ = 0;
  computeJD(&y);
  *pRc = SQLITE_OK;
  return y.iJD - x.iJD;
}
#endif /* SQLITE_OMIT_LOCALTIME */

/*
** Process a modifier to a date-time stamp.  The modifiers are
** as follows:
................................................................................
**     start of week
**     start of day
**     weekday N
**     unixepoch
**     localtime
**     utc
**
** Return 0 on success and 1 if there is any kind of error. If the error
** is in a system call (i.e. localtime()), then an error message is written
** to context pCtx. If the error is an unrecognized modifier, no error is
** written to pCtx.
*/
static int parseModifier(sqlite3_context *pCtx, const char *zMod, DateTime *p){
  int rc = 1;
  int n;
  double r;
  char *z, zBuf[30];
  z = zBuf;
  for(n=0; n<ArraySize(zBuf)-1 && zMod[n]; n++){
    z[n] = (char)sqlite3UpperToLower[(u8)zMod[n]];
................................................................................
      /*    localtime
      **
      ** Assuming the current time value is UTC (a.k.a. GMT), shift it to
      ** show local time.
      */
      if( strcmp(z, "localtime")==0 ){
        computeJD(p);
        p->iJD += localtimeOffset(p, pCtx, &rc);
        clearYMD_HMS_TZ(p);

      }
      break;
    }
#endif
    case 'u': {
      /*
      **    unixepoch
................................................................................
        clearYMD_HMS_TZ(p);
        rc = 0;
      }
#ifndef SQLITE_OMIT_LOCALTIME
      else if( strcmp(z, "utc")==0 ){
        sqlite3_int64 c1;
        computeJD(p);
        c1 = localtimeOffset(p, pCtx, &rc);
        if( rc==SQLITE_OK ){
          p->iJD -= c1;
          clearYMD_HMS_TZ(p);
          p->iJD += c1 - localtimeOffset(p, pCtx, &rc);

        }
      }
#endif
      break;
    }
    case 'w': {
      /*
      **    weekday N
................................................................................
  }else{
    z = sqlite3_value_text(argv[0]);
    if( !z || parseDateOrTime(context, (char*)z, p) ){
      return 1;
    }
  }
  for(i=1; i<argc; i++){
    z = sqlite3_value_text(argv[i]);
    if( z==0 || parseModifier(context, (char*)z, p) ) return 1;

  }
  return 0;
}


/*
** The following routines implement the various date and time functions
................................................................................
    while( zIn!=zTerm && (*zIn & 0xc0)==0x80 ){            \
      c = (c<<6) + (0x3f & *(zIn++));                      \
    }                                                      \
    if( c<0x80                                             \
        || (c&0xFFFFF800)==0xD800                          \
        || (c&0xFFFFFFFE)==0xFFFE ){  c = 0xFFFD; }        \
  }
SQLITE_PRIVATE u32 sqlite3Utf8Read(
  const unsigned char *zIn,       /* First byte of UTF-8 character */
  const unsigned char **pzNext    /* Write first byte past UTF-8 char here */
){
  unsigned int c;

  /* Same as READ_UTF8() above but without the zTerm parameter.
  ** For this routine, we assume the UTF8 string is always zero-terminated.
................................................................................
# endif
#endif /* SQLITE_ENABLE_LOCKING_STYLE */

#if defined(__APPLE__) || (SQLITE_ENABLE_LOCKING_STYLE && !OS_VXWORKS)
# include <sys/mount.h>
#endif

#ifdef HAVE_UTIME
# include <utime.h>
#endif

/*
** Allowed values of unixFile.fsFlags
*/
#define SQLITE_FSFLAGS_IS_MSDOS     0x1

/*
** If we are to be thread-safe, include the pthreads header and define
................................................................................


  /* If we have any lock, then the lock file already exists.  All we have
  ** to do is adjust our internal record of the lock level.
  */
  if( pFile->eFileLock > NO_LOCK ){
    pFile->eFileLock = eFileLock;

    /* Always update the timestamp on the old file */
#ifdef HAVE_UTIME
    utime(zLockFile, NULL);
#else
    utimes(zLockFile, NULL);
#endif
    return SQLITE_OK;
  }
  
  /* grab an exclusive lock */
  fd = robust_open(zLockFile,O_RDONLY|O_CREAT|O_EXCL,0600);
................................................................................
*/
struct unixShmNode {
  unixInodeInfo *pInode;     /* unixInodeInfo that owns this SHM node */
  sqlite3_mutex *mutex;      /* Mutex to access this object */
  char *zFilename;           /* Name of the mmapped file */
  int h;                     /* Open file descriptor */
  int szRegion;              /* Size of shared-memory regions */
  u16 nRegion;               /* Size of array apRegion */
  u8 isReadonly;             /* True if read-only */
  char **apRegion;           /* Array of mapped shared-memory regions */
  int nRef;                  /* Number of unixShm objects pointing to this */
  unixShm *pFirst;           /* All unixShm objects pointing to this */
#ifdef SQLITE_DEBUG
  u8 exclMask;               /* Mask of exclusive locks held */
  u8 sharedMask;             /* Mask of shared locks held */
  u8 nextShmId;              /* Next available unixShm.id value */
................................................................................
      goto shm_open_err;
    }

    if( pInode->bProcessLock==0 ){
      pShmNode->h = robust_open(zShmFilename, O_RDWR|O_CREAT,
                               (sStat.st_mode & 0777));
      if( pShmNode->h<0 ){
        const char *zRO;
        zRO = sqlite3_uri_parameter(pDbFd->zPath, "readonly_shm");
        if( zRO && sqlite3GetBoolean(zRO) ){
          pShmNode->h = robust_open(zShmFilename, O_RDONLY,
                                    (sStat.st_mode & 0777));
          pShmNode->isReadonly = 1;
        }
        if( pShmNode->h<0 ){
          rc = unixLogError(SQLITE_CANTOPEN_BKPT, "open", zShmFilename);
          goto shm_open_err;
        }
      }
  
      /* Check to see if another process is holding the dead-man switch.
      ** If not, truncate the file to zero length. 
      */
      rc = SQLITE_OK;
      if( unixShmSystemLock(pShmNode, F_WRLCK, UNIX_SHM_DMS, 1)==SQLITE_OK ){
................................................................................
      rc = SQLITE_IOERR_NOMEM;
      goto shmpage_out;
    }
    pShmNode->apRegion = apNew;
    while(pShmNode->nRegion<=iRegion){
      void *pMem;
      if( pShmNode->h>=0 ){
        pMem = mmap(0, szRegion,
            pShmNode->isReadonly ? PROT_READ : PROT_READ|PROT_WRITE, 
            MAP_SHARED, pShmNode->h, pShmNode->nRegion*szRegion
        );
        if( pMem==MAP_FAILED ){
          rc = unixLogError(SQLITE_IOERR_SHMMAP, "mmap", pShmNode->zFilename);
          goto shmpage_out;
        }
      }else{
................................................................................

shmpage_out:
  if( pShmNode->nRegion>iRegion ){
    *pp = pShmNode->apRegion[iRegion];
  }else{
    *pp = 0;
  }
  if( pShmNode->isReadonly && rc==SQLITE_OK ) rc = SQLITE_READONLY;
  sqlite3_mutex_leave(pShmNode->mutex);
  return rc;
}

/*
** Change the lock state for a shared-memory segment.
**
................................................................................
    if( nRem>0 ){
      pFile->lastErrno = GetLastError();
      rc = 1;
    }
  }

  if( rc ){
    if(   ( pFile->lastErrno==ERROR_HANDLE_DISK_FULL )
       || ( pFile->lastErrno==ERROR_DISK_FULL )){
      return SQLITE_FULL;
    }
    return winLogError(SQLITE_IOERR_WRITE, "winWrite", pFile->zPath);
  }
  return SQLITE_OK;
}

................................................................................
    );
    pCache->pSynced = pPg;
    if( !pPg ){
      for(pPg=pCache->pDirtyTail; pPg && pPg->nRef; pPg=pPg->pDirtyPrev);
    }
    if( pPg ){
      int rc;
#ifdef SQLITE_LOG_CACHE_SPILL
      sqlite3_log(SQLITE_FULL, 
                  "spill page %d making room for %d - cache used: %d/%d",
                  pPg->pgno, pgno,
                  sqlite3GlobalConfig.pcache.xPagecount(pCache->pCache),
                  pCache->nMax);
#endif
      rc = pCache->xStress(pCache->pStress, pPg);
      if( rc!=SQLITE_OK && rc!=SQLITE_BUSY ){
        return rc;
      }
    }

    pPage = sqlite3GlobalConfig.pcache.xFetch(pCache->pCache, pgno, 2);
................................................................................
  pCache = (PCache1 *)sqlite3_malloc(sz);
  if( pCache ){
    memset(pCache, 0, sz);
    if( separateCache ){
      pGroup = (PGroup*)&pCache[1];
      pGroup->mxPinned = 10;
    }else{
      pGroup = &pcache1.grp;
    }
    pCache->pGroup = pGroup;
    pCache->szPage = szPage;
    pCache->bPurgeable = (bPurgeable ? 1 : 0);
    if( bPurgeable ){
      pCache->nMin = 10;
      pcache1EnterMutex(pGroup);
................................................................................
  int nWiData;               /* Size of array apWiData */
  volatile u32 **apWiData;   /* Pointer to wal-index content in memory */
  u32 szPage;                /* Database page size */
  i16 readLock;              /* Which read lock is being held.  -1 for none */
  u8 exclusiveMode;          /* Non-zero if connection is in exclusive mode */
  u8 writeLock;              /* True if in a write transaction */
  u8 ckptLock;               /* True if holding a checkpoint lock */
  u8 readOnly;               /* WAL_RDWR, WAL_RDONLY, or WAL_SHM_RDONLY */
  WalIndexHdr hdr;           /* Wal-index header for current transaction */
  const char *zWalName;      /* Name of WAL file */
  u32 nCkpt;                 /* Checkpoint sequence counter in the wal-header */
#ifdef SQLITE_DEBUG
  u8 lockError;              /* True if a locking error has occurred */
#endif
};
................................................................................
/*
** Candidate values for Wal.exclusiveMode.
*/
#define WAL_NORMAL_MODE     0
#define WAL_EXCLUSIVE_MODE  1     
#define WAL_HEAPMEMORY_MODE 2

/*
** Possible values for WAL.readOnly
*/
#define WAL_RDWR        0    /* Normal read/write connection */
#define WAL_RDONLY      1    /* The WAL file is readonly */
#define WAL_SHM_RDONLY  2    /* The SHM file is readonly */

/*
** Each page of the wal-index mapping contains a hash-table made up of
** an array of HASHTABLE_NSLOT elements of the following type.
*/
typedef u16 ht_slot;

/*
................................................................................
    if( pWal->exclusiveMode==WAL_HEAPMEMORY_MODE ){
      pWal->apWiData[iPage] = (u32 volatile *)sqlite3MallocZero(WALINDEX_PGSZ);
      if( !pWal->apWiData[iPage] ) rc = SQLITE_NOMEM;
    }else{
      rc = sqlite3OsShmMap(pWal->pDbFd, iPage, WALINDEX_PGSZ, 
          pWal->writeLock, (void volatile **)&pWal->apWiData[iPage]
      );
      if( rc==SQLITE_READONLY ){
        pWal->readOnly |= WAL_SHM_RDONLY;
        rc = SQLITE_OK;
      }
    }
  }

  *ppPage = pWal->apWiData[iPage];
  assert( iPage==0 || *ppPage || rc!=SQLITE_OK );
  return rc;
}
................................................................................
  pRet->zWalName = zWalName;
  pRet->exclusiveMode = (bNoShm ? WAL_HEAPMEMORY_MODE: WAL_NORMAL_MODE);

  /* Open file handle on the write-ahead log file. */
  flags = (SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|SQLITE_OPEN_WAL);
  rc = sqlite3OsOpen(pVfs, zWalName, pRet->pWalFd, flags, &flags);
  if( rc==SQLITE_OK && flags&SQLITE_OPEN_READONLY ){
    pRet->readOnly = WAL_RDONLY;
  }

  if( rc!=SQLITE_OK ){
    walIndexClose(pRet, 0);
    sqlite3OsClose(pRet->pWalFd);
    sqlite3_free(pRet);
  }else{
................................................................................
  */
  badHdr = (page0 ? walIndexTryHdr(pWal, pChanged) : 1);

  /* If the first attempt failed, it might have been due to a race
  ** with a writer.  So get a WRITE lock and try again.
  */
  assert( badHdr==0 || pWal->writeLock==0 );
  if( badHdr ){
    if( pWal->readOnly & WAL_SHM_RDONLY ){
      if( SQLITE_OK==(rc = walLockShared(pWal, WAL_WRITE_LOCK)) ){
        walUnlockShared(pWal, WAL_WRITE_LOCK);
        rc = SQLITE_READONLY_RECOVERY;
      }
    }else if( SQLITE_OK==(rc = walLockExclusive(pWal, WAL_WRITE_LOCK, 1)) ){
      pWal->writeLock = 1;
      if( SQLITE_OK==(rc = walIndexPage(pWal, 0, &page0)) ){
        badHdr = walIndexTryHdr(pWal, pChanged);
        if( badHdr ){
          /* If the wal-index header is still malformed even while holding
          ** a WRITE lock, it can only mean that the header is corrupted and
          ** needs to be reconstructed.  So run recovery to do exactly that.
          */
          rc = walIndexRecover(pWal);
          *pChanged = 1;
        }
      }
      pWal->writeLock = 0;
      walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1);
    }
  }

  /* If the header is read successfully, check the version number to make
  ** sure the wal-index was not constructed with some future format that
  ** this version of SQLite cannot understand.
  */
  if( badHdr==0 && pWal->hdr.iVersion!=WALINDEX_MAX_VERSION ){
................................................................................
      assert( thisMark!=READMARK_NOT_USED );
      mxReadMark = thisMark;
      mxI = i;
    }
  }
  /* There was once an "if" here. The extra "{" is to preserve indentation. */
  {
    if( (pWal->readOnly & WAL_SHM_RDONLY)==0
     && (mxReadMark<pWal->hdr.mxFrame || mxI==0)
    ){
      for(i=1; i<WAL_NREADER; i++){
        rc = walLockExclusive(pWal, WAL_READ_LOCK(i), 1);
        if( rc==SQLITE_OK ){
          mxReadMark = pInfo->aReadMark[i] = pWal->hdr.mxFrame;
          mxI = i;
          walUnlockExclusive(pWal, WAL_READ_LOCK(i), 1);
          break;
        }else if( rc!=SQLITE_BUSY ){
          return rc;
        }
      }
    }
    if( mxI==0 ){
      assert( rc==SQLITE_BUSY || (pWal->readOnly & WAL_SHM_RDONLY)!=0 );
      return rc==SQLITE_BUSY ? WAL_RETRY : SQLITE_READONLY_CANTLOCK;
    }

    rc = walLockShared(pWal, WAL_READ_LOCK(mxI));
    if( rc ){
      return rc==SQLITE_BUSY ? WAL_RETRY : rc;
    }
    /* Now that the read-lock has been obtained, check that neither the
................................................................................
  int rc;                         /* Return code */
  int isChanged = 0;              /* True if a new wal-index header is loaded */
  int eMode2 = eMode;             /* Mode to pass to walCheckpoint() */

  assert( pWal->ckptLock==0 );
  assert( pWal->writeLock==0 );

  if( pWal->readOnly ) return SQLITE_READONLY;
  WALTRACE(("WAL%p: checkpoint begins\n", pWal));
  rc = walLockExclusive(pWal, WAL_CKPT_LOCK, 1);
  if( rc ){
    /* Usually this is SQLITE_BUSY meaning that another thread or process
    ** is already running a checkpoint, or maybe a recovery.  But it might
    ** also be SQLITE_IOERR. */
    return rc;
................................................................................
** the page, 1 means the second cell, and so forth) return a pointer
** to the cell content.
**
** This routine works only for pages that do not contain overflow cells.
*/
#define findCell(P,I) \
  ((P)->aData + ((P)->maskPage & get2byte(&(P)->aData[(P)->cellOffset+2*(I)])))
#define findCellv2(D,M,O,I) (D+(M&get2byte(D+(O+2*(I)))))


/*
** This a more complex version of findCell() that works for
** pages that do contain overflow cells.
*/
static u8 *findOverflowCell(MemPage *pPage, int iCell){
  int i;
................................................................................
  if( pCur->eState==CURSOR_INVALID ){
    *pRes = -1;
    assert( pCur->apPage[pCur->iPage]->nCell==0 );
    return SQLITE_OK;
  }
  assert( pCur->apPage[0]->intKey || pIdxKey );
  for(;;){
    int lwr, upr, idx;
    Pgno chldPg;
    MemPage *pPage = pCur->apPage[pCur->iPage];
    int c;

    /* pPage->nCell must be greater than zero. If this is the root-page
    ** the cursor would have been INVALID above and this for(;;) loop
    ** not run. If this is not the root-page, then the moveToChild() routine
................................................................................
    ** be the right kind (index or table) of b-tree page. Otherwise
    ** a moveToChild() or moveToRoot() call would have detected corruption.  */
    assert( pPage->nCell>0 );
    assert( pPage->intKey==(pIdxKey==0) );
    lwr = 0;
    upr = pPage->nCell-1;
    if( biasRight ){
      pCur->aiIdx[pCur->iPage] = (u16)(idx = upr);
    }else{
      pCur->aiIdx[pCur->iPage] = (u16)(idx = (upr+lwr)/2);
    }
    for(;;){

      u8 *pCell;                          /* Pointer to current cell in pPage */

      assert( idx==pCur->aiIdx[pCur->iPage] );
      pCur->info.nSize = 0;
      pCell = findCell(pPage, idx) + pPage->childPtrSize;
      if( pPage->intKey ){
        i64 nCellKey;
        if( pPage->hasData ){
          u32 dummy;
          pCell += getVarint32(pCell, dummy);
................................................................................
        lwr = idx+1;
      }else{
        upr = idx-1;
      }
      if( lwr>upr ){
        break;
      }
      pCur->aiIdx[pCur->iPage] = (u16)(idx = (lwr+upr)/2);
    }
    assert( lwr==upr+1 );
    assert( pPage->isInit );
    if( pPage->leaf ){
      chldPg = 0;
    }else if( lwr>=pPage->nCell ){
      chldPg = get4byte(&pPage->aData[pPage->hdrOffset+8]);
................................................................................
** The cell content is not freed or deallocated.  It is assumed that
** the cell content has been copied someplace else.  This routine just
** removes the reference to the cell from pPage.
**
** "sz" must be the number of bytes in the cell.
*/
static void dropCell(MemPage *pPage, int idx, int sz, int *pRC){

  u32 pc;         /* Offset to cell content of cell being deleted */
  u8 *data;       /* pPage->aData */
  u8 *ptr;        /* Used to move bytes around within data[] */
  u8 *endPtr;     /* End of loop */
  int rc;         /* The return code */
  int hdr;        /* Beginning of the header.  0 most pages.  100 page 1 */

  if( *pRC ) return;

  assert( idx>=0 && idx<pPage->nCell );
  assert( sz==cellSize(pPage, idx) );
................................................................................
    return;
  }
  rc = freeSpace(pPage, pc, sz);
  if( rc ){
    *pRC = rc;
    return;
  }
  endPtr = &data[pPage->cellOffset + 2*pPage->nCell - 2];
  assert( (SQLITE_PTR_TO_INT(ptr)&1)==0 );  /* ptr is always 2-byte aligned */
  while( ptr<endPtr ){
    *(u16*)ptr = *(u16*)&ptr[2];
    ptr += 2;
  }
  pPage->nCell--;
  put2byte(&data[hdr+3], pPage->nCell);
  pPage->nFree += 2;
}

/*
................................................................................
  int idx = 0;      /* Where to write new cell content in data[] */
  int j;            /* Loop counter */
  int end;          /* First byte past the last cell pointer in data[] */
  int ins;          /* Index in data[] where new cell pointer is inserted */
  int cellOffset;   /* Address of first cell pointer in data[] */
  u8 *data;         /* The content of the whole page */
  u8 *ptr;          /* Used for moving information around in data[] */
  u8 *endPtr;       /* End of the loop */

  int nSkip = (iChild ? 4 : 0);

  if( *pRC ) return;

  assert( i>=0 && i<=pPage->nCell+pPage->nOverflow );
  assert( pPage->nCell<=MX_CELL(pPage->pBt) && MX_CELL(pPage->pBt)<=10921 );
................................................................................
    assert( idx+sz <= (int)pPage->pBt->usableSize );
    pPage->nCell++;
    pPage->nFree -= (u16)(2 + sz);
    memcpy(&data[idx+nSkip], pCell+nSkip, sz-nSkip);
    if( iChild ){
      put4byte(&data[idx], iChild);
    }
    ptr = &data[end];
    endPtr = &data[ins];
    assert( (SQLITE_PTR_TO_INT(ptr)&1)==0 );  /* ptr is always 2-byte aligned */
    while( ptr>endPtr ){
      *(u16*)ptr = *(u16*)&ptr[-2];
      ptr -= 2;
    }
    put2byte(&data[ins], idx);
    put2byte(&data[pPage->hdrOffset+3], pPage->nCell);
#ifndef SQLITE_OMIT_AUTOVACUUM
    if( pPage->pBt->autoVacuum ){
      /* The cell may contain a pointer to an overflow page. If so, write
      ** the entry for the overflow page into the pointer map.
................................................................................
  /* Check that the page has just been zeroed by zeroPage() */
  assert( pPage->nCell==0 );
  assert( get2byteNotZero(&data[hdr+5])==nUsable );

  pCellptr = &data[pPage->cellOffset + nCell*2];
  cellbody = nUsable;
  for(i=nCell-1; i>=0; i--){
    u16 sz = aSize[i];
    pCellptr -= 2;
    cellbody -= sz;
    put2byte(pCellptr, cellbody);
    memcpy(&data[cellbody], apCell[i], sz);
  }
  put2byte(&data[hdr+3], nCell);
  put2byte(&data[hdr+5], cellbody);
  pPage->nFree -= (nCell*2 + nUsable - cellbody);
  pPage->nCell = (u16)nCell;
}

................................................................................
    ** process of being overwritten.  */
    MemPage *pOld = apCopy[i] = (MemPage*)&aSpace1[pBt->pageSize + k*i];
    memcpy(pOld, apOld[i], sizeof(MemPage));
    pOld->aData = (void*)&pOld[1];
    memcpy(pOld->aData, apOld[i]->aData, pBt->pageSize);

    limit = pOld->nCell+pOld->nOverflow;
    if( pOld->nOverflow>0 ){
      for(j=0; j<limit; j++){
        assert( nCell<nMaxCells );
        apCell[nCell] = findOverflowCell(pOld, j);
        szCell[nCell] = cellSizePtr(pOld, apCell[nCell]);
        nCell++;
      }
    }else{
      u8 *aData = pOld->aData;
      u16 maskPage = pOld->maskPage;
      u16 cellOffset = pOld->cellOffset;
      for(j=0; j<limit; j++){
        assert( nCell<nMaxCells );
        apCell[nCell] = findCellv2(aData, maskPage, cellOffset, j);
        szCell[nCell] = cellSizePtr(pOld, apCell[nCell]);
        nCell++;
      }
    }       
    if( i<nOld-1 && !leafData){
      u16 sz = (u16)szNew[i];
      u8 *pTemp;
      assert( nCell<nMaxCells );
      szCell[nCell] = sz;
      pTemp = &aSpace1[iSpace1];
      iSpace1 += sz;
................................................................................
  pOp->opcode = (u8)op;
  pOp->p5 = 0;
  pOp->p1 = p1;
  pOp->p2 = p2;
  pOp->p3 = p3;
  pOp->p4.p = 0;
  pOp->p4type = P4_NOTUSED;







#ifdef SQLITE_DEBUG
  pOp->zComment = 0;
  if( sqlite3VdbeAddopTrace ) sqlite3VdbePrintOp(0, i, &p->aOp[i]);
#endif
#ifdef VDBE_PROFILE
  pOp->cycles = 0;
  pOp->cnt = 0;
................................................................................
  const char *zP4,    /* The P4 operand */
  int p4type          /* P4 operand type */
){
  int addr = sqlite3VdbeAddOp3(p, op, p1, p2, p3);
  sqlite3VdbeChangeP4(p, addr, zP4, p4type);
  return addr;
}

/*
** Add an OP_ParseSchema opcode.  This routine is broken out from
** sqlite3VdbeAddOp4() since it needs to also local all btrees.
**
** The zWhere string must have been obtained from sqlite3_malloc().
** This routine will take ownership of the allocated memory.
*/
SQLITE_PRIVATE void sqlite3VdbeAddParseSchemaOp(Vdbe *p, int iDb, char *zWhere){
  int j;
  int addr = sqlite3VdbeAddOp3(p, OP_ParseSchema, iDb, 0, 0);
  sqlite3VdbeChangeP4(p, addr, zWhere, P4_DYNAMIC);
  for(j=0; j<p->db->nDb; j++) sqlite3VdbeUsesBtree(p, j);
}

/*
** Add an opcode that includes the p4 value as an integer.
*/
SQLITE_PRIVATE int sqlite3VdbeAddOp4Int(
  Vdbe *p,            /* Add the opcode to this VM */
  int op,             /* The new opcode */
................................................................................
  }else{
    *pnByte += nByte;
  }
  return pBuf;
}

/*
** Rewind the VDBE back to the beginning in preparation for
** running it.
*/
SQLITE_PRIVATE void sqlite3VdbeRewind(Vdbe *p){
#if defined(SQLITE_DEBUG) || defined(VDBE_PROFILE)
  int i;
#endif
  assert( p!=0 );
  assert( p->magic==VDBE_MAGIC_INIT );

  /* There should be at least one opcode.
  */
  assert( p->nOp>0 );

  /* Set the magic to VDBE_MAGIC_RUN sooner rather than later. */
  p->magic = VDBE_MAGIC_RUN;

#ifdef SQLITE_DEBUG
  for(i=1; i<p->nMem; i++){
    assert( p->aMem[i].db==p->db );
  }
#endif
  p->pc = -1;
  p->rc = SQLITE_OK;
  p->errorAction = OE_Abort;
  p->magic = VDBE_MAGIC_RUN;
  p->nChange = 0;
  p->cacheCtr = 1;
  p->minWriteFileFormat = 255;
  p->iStatement = 0;
  p->nFkConstraint = 0;
#ifdef VDBE_PROFILE
  for(i=0; i<p->nOp; i++){
    p->aOp[i].cnt = 0;
    p->aOp[i].cycles = 0;
  }
#endif
}

/*
** Prepare a virtual machine for execution for the first time after
** creating the virtual machine.  This involves things such
** as allocating stack space and initializing the program counter.
** After the VDBE has be prepped, it can be executed by one or more
** calls to sqlite3VdbeExec().  
**


** This function may be called exact once on a each virtual machine.
** After this routine is called the VM has been "packaged" and is ready
** to run.  After this routine is called, futher calls to 
** sqlite3VdbeAddOp() functions are prohibited.  This routine disconnects
** the Vdbe from the Parse object that helped generate it so that the
** the Vdbe becomes an independent entity and the Parse object can be
** destroyed.
**







** Use the sqlite3VdbeRewind() procedure to restore a virtual machine back
** to its initial state after it has been run.
*/
SQLITE_PRIVATE void sqlite3VdbeMakeReady(
  Vdbe *p,                       /* The VDBE */






  Parse *pParse                  /* Parsing context */
){


  sqlite3 *db;                   /* The database connection */
  int nVar;                      /* Number of parameters */
  int nMem;                      /* Number of VM memory registers */
  int nCursor;                   /* Number of cursors required */
  int nArg;                      /* Number of arguments in subprograms */
  int n;                         /* Loop counter */
  u8 *zCsr;                      /* Memory available for allocation */
  u8 *zEnd;                      /* First byte past allocated memory */
  int nByte;                     /* How much extra memory is needed */

  assert( p!=0 );
  assert( p->nOp>0 );
  assert( pParse!=0 );
  assert( p->magic==VDBE_MAGIC_INIT );
  db = p->db;
  assert( db->mallocFailed==0 );
  nVar = pParse->nVar;
  nMem = pParse->nMem;
  nCursor = pParse->nTab;
  nArg = pParse->nMaxArg;
  







  /* For each cursor required, also allocate a memory cell. Memory
  ** cells (nMem+1-nCursor)..nMem, inclusive, will never be used by
  ** the vdbe program. Instead they are used to allocate space for
  ** VdbeCursor/BtCursor structures. The blob of memory associated with 
  ** cursor 0 is stored in memory cell nMem. Memory cell (nMem-1)
  ** stores the blob of memory associated with cursor 1, etc.
  **
  ** See also: allocateCursor().
  */
  nMem += nCursor;

  /* Allocate space for memory registers, SQL variables, VDBE cursors and 
  ** an array to marshal SQL function arguments in.


  */

  zCsr = (u8*)&p->aOp[p->nOp];       /* Memory avaliable for allocation */
  zEnd = (u8*)&p->aOp[p->nOpAlloc];  /* First byte past end of zCsr[] */


  resolveP2Values(p, &nArg);
  p->usesStmtJournal = (u8)(pParse->isMultiWrite && pParse->mayAbort);
  if( pParse->explain && nMem<10 ){
    nMem = 10;
  }
  memset(zCsr, 0, zEnd-zCsr);
  zCsr += (zCsr - (u8*)0)&7;
  assert( EIGHT_BYTE_ALIGNMENT(zCsr) );

  /* Memory for registers, parameters, cursor, etc, is allocated in two
  ** passes.  On the first pass, we try to reuse unused space at the 
  ** end of the opcode array.  If we are unable to satisfy all memory
  ** requirements by reusing the opcode array tail, then the second
  ** pass will fill in the rest using a fresh allocation.  
  **
  ** This two-pass approach that reuses as much memory as possible from
  ** the leftover space at the end of the opcode array can significantly
  ** reduce the amount of memory held by a prepared statement.
  */
  do {
    nByte = 0;
    p->aMem = allocSpace(p->aMem, nMem*sizeof(Mem), &zCsr, zEnd, &nByte);
    p->aVar = allocSpace(p->aVar, nVar*sizeof(Mem), &zCsr, zEnd, &nByte);
    p->apArg = allocSpace(p->apArg, nArg*sizeof(Mem*), &zCsr, zEnd, &nByte);
    p->azVar = allocSpace(p->azVar, nVar*sizeof(char*), &zCsr, zEnd, &nByte);
    p->apCsr = allocSpace(p->apCsr, nCursor*sizeof(VdbeCursor*),
                          &zCsr, zEnd, &nByte);
    if( nByte ){
      p->pFree = sqlite3DbMallocZero(db, nByte);
    }
    zCsr = p->pFree;
    zEnd = &zCsr[nByte];
  }while( nByte && !db->mallocFailed );

  p->nCursor = (u16)nCursor;
  if( p->aVar ){
    p->nVar = (ynVar)nVar;
    for(n=0; n<nVar; n++){
      p->aVar[n].flags = MEM_Null;
      p->aVar[n].db = db;
    }
  }
  if( p->azVar ){
    p->nzVar = pParse->nzVar;
    memcpy(p->azVar, pParse->azVar, p->nzVar*sizeof(p->azVar[0]));
    memset(pParse->azVar, 0, pParse->nzVar*sizeof(pParse->azVar[0]));
  }
  if( p->aMem ){
    p->aMem--;                      /* aMem[] goes from 1..nMem */
    p->nMem = nMem;                 /*       not from 0..nMem-1 */
    for(n=1; n<=nMem; n++){
      p->aMem[n].flags = MEM_Null;
      p->aMem[n].db = db;
    }
  }










  p->explain = pParse->explain;















  sqlite3VdbeRewind(p);
}

/*
** Close a VDBE cursor and release all the resources that cursor 
** happens to hold.
*/
SQLITE_PRIVATE void sqlite3VdbeFreeCursor(Vdbe *p, VdbeCursor *pCx){
................................................................................
** Free all memory associated with the Vdbe passed as the second argument.
** The difference between this function and sqlite3VdbeDelete() is that
** VdbeDelete() also unlinks the Vdbe from the list of VMs associated with
** the database connection.
*/
SQLITE_PRIVATE void sqlite3VdbeDeleteObject(sqlite3 *db, Vdbe *p){
  SubProgram *pSub, *pNext;
  int i;
  assert( p->db==0 || p->db==db );
  releaseMemArray(p->aVar, p->nVar);
  releaseMemArray(p->aColName, p->nResColumn*COLNAME_N);
  for(pSub=p->pProgram; pSub; pSub=pNext){
    pNext = pSub->pNext;
    vdbeFreeOpArray(db, pSub->aOp, pSub->nOp);
    sqlite3DbFree(db, pSub);
  }
  for(i=p->nzVar-1; i>=0; i--) sqlite3DbFree(db, p->azVar[i]);
  vdbeFreeOpArray(db, p->aOp, p->nOp);
  sqlite3DbFree(db, p->aLabel);
  sqlite3DbFree(db, p->aColName);
  sqlite3DbFree(db, p->zSql);
  sqlite3DbFree(db, p->pFree);
  sqlite3DbFree(db, p);
}
................................................................................
  u = 0;
  while( idx<szHdr && u<p->nField && d<=nKey ){
    u32 serial_type;

    idx += getVarint32(&aKey[idx], serial_type);
    pMem->enc = pKeyInfo->enc;
    pMem->db = pKeyInfo->db;
    /* pMem->flags = 0; // sqlite3VdbeSerialGet() will set this for us */
    pMem->zMalloc = 0;
    d += sqlite3VdbeSerialGet(&aKey[d], serial_type, pMem);
    pMem++;
    u++;
  }
  assert( u<=pKeyInfo->nField + 1 );
  p->nField = u;
................................................................................
  return (void*)p;
}

/*
** This routine destroys a UnpackedRecord object.
*/
SQLITE_PRIVATE void sqlite3VdbeDeleteUnpackedRecord(UnpackedRecord *p){
#ifdef SQLITE_DEBUG
  int i;
  Mem *pMem;

  assert( p!=0 );
  assert( p->flags & UNPACKED_NEED_DESTROY );
  for(i=0, pMem=p->aMem; i<p->nField; i++, pMem++){
    /* The unpacked record is always constructed by the
    ** sqlite3VdbeUnpackRecord() function above, which makes all
    ** strings and blobs static.  And none of the elements are
    ** ever transformed, so there is never anything to delete.
    */
    if( NEVER(pMem->zMalloc) ) sqlite3VdbeMemRelease(pMem);
  }
#endif
  if( p->flags & UNPACKED_NEED_FREE ){
    sqlite3DbFree(p->pKeyInfo->db, p);
  }
}

/*
** This function compares the two table rows or index records
................................................................................
  int rc;
  if( pStmt==0 ){
    rc = SQLITE_OK;
  }else{
    Vdbe *v = (Vdbe*)pStmt;
    sqlite3_mutex_enter(v->db->mutex);
    rc = sqlite3VdbeReset(v);
    sqlite3VdbeRewind(v);
    assert( (rc & (v->db->errMask))==rc );
    rc = sqlite3ApiExit(v->db, rc);
    sqlite3_mutex_leave(v->db->mutex);
  }
  return rc;
}

................................................................................
    ** caller. Set the error code in the database handle to the same value.
    */ 
    rc = db->errCode = p->rc;
  }
  return (rc&db->errMask);
}

/*
** The maximum number of times that a statement will try to reparse
** itself before giving up and returning SQLITE_SCHEMA.
*/
#ifndef SQLITE_MAX_SCHEMA_RETRY
# define SQLITE_MAX_SCHEMA_RETRY 5
#endif

/*
** This is the top-level implementation of sqlite3_step().  Call
** sqlite3Step() to do most of the work.  If a schema error occurs,
** call sqlite3Reprepare() and try again.
*/
SQLITE_API int sqlite3_step(sqlite3_stmt *pStmt){
  int rc = SQLITE_OK;      /* Result from sqlite3Step() */
................................................................................

  if( vdbeSafetyNotNull(v) ){
    return SQLITE_MISUSE_BKPT;
  }
  db = v->db;
  sqlite3_mutex_enter(db->mutex);
  while( (rc = sqlite3Step(v))==SQLITE_SCHEMA
         && cnt++ < SQLITE_MAX_SCHEMA_RETRY
         && (rc2 = rc = sqlite3Reprepare(v))==SQLITE_OK ){
    sqlite3_reset(pStmt);
    v->expired = 0;
  }
  if( rc2!=SQLITE_OK && ALWAYS(v->isPrepareV2) && ALWAYS(db->pErr) ){
    /* This case occurs after failing to recompile an sql statement. 
    ** The error message from the SQL compiler has already been loaded 
................................................................................
** This routine is added to support DBD::SQLite.  
*/
SQLITE_API int sqlite3_bind_parameter_count(sqlite3_stmt *pStmt){
  Vdbe *p = (Vdbe*)pStmt;
  return p ? p->nVar : 0;
}



























/*
** Return the name of a wildcard parameter.  Return NULL if the index
** is out of range or if the wildcard is unnamed.
**
** The result is always UTF-8.
*/
SQLITE_API const char *sqlite3_bind_parameter_name(sqlite3_stmt *pStmt, int i){
  Vdbe *p = (Vdbe*)pStmt;
  if( p==0 || i<1 || i>p->nzVar ){
    return 0;
  }

  return p->azVar[i-1];
}

/*
** Given a wildcard parameter name, return the index of the variable
** with that name.  If there is no variable with the given name,
** return 0.
*/
SQLITE_PRIVATE int sqlite3VdbeParameterIndex(Vdbe *p, const char *zName, int nName){
  int i;
  if( p==0 ){
    return 0;
  }

  if( zName ){
    for(i=0; i<p->nzVar; i++){
      const char *z = p->azVar[i];
      if( z && memcmp(z,zName,nName)==0 && z[nName]==0 ){
        return i+1;
      }
    }
  }
  return 0;
................................................................................
      int i;
      sqlite_int64 rowid;
      Mem **apArg;
      Mem *pX;
    } cm;
    struct OP_Trace_stack_vars {
      char *zTrace;
      char *z;
    } cn;
  } u;
  /* End automatically generated code
  ********************************************************************/

  assert( p->magic==VDBE_MAGIC_RUN );  /* sqlite3_step() verifies this */
  sqlite3VdbeEnter(p);
................................................................................
  REGISTER_TRACE(pOp->p1, pIn1);
  pc = u.aa.pcDest;
  break;
}

/* Opcode:  HaltIfNull  P1 P2 P3 P4 *
**
** Check the value in register P3.  If it is NULL then Halt using
** parameter P1, P2, and P4 as if this were a Halt instruction.  If the
** value in register P3 is not NULL, then this routine is a no-op.
*/
case OP_HaltIfNull: {      /* in3 */
  pIn3 = &aMem[pOp->p3];
  if( (pIn3->flags & MEM_Null)==0 ) break;
  /* Fall through into OP_Halt */
................................................................................
*/
case OP_Variable: {            /* out2-prerelease */
#if 0  /* local variables moved into u.ab */
  Mem *pVar;       /* Value being transferred */
#endif /* local variables moved into u.ab */

  assert( pOp->p1>0 && pOp->p1<=p->nVar );
  assert( pOp->p4.z==0 || pOp->p4.z==p->azVar[pOp->p1-1] );
  u.ab.pVar = &p->aVar[pOp->p1 - 1];
  if( sqlite3VdbeMemTooBig(u.ab.pVar) ){
    goto too_big;
  }
  sqlite3VdbeMemShallowCopy(pOut, u.ab.pVar, MEM_Static);
  UPDATE_MAX_BLOBSIZE(pOut);
  break;
................................................................................
    assert( pOp[-1].p4type==P4_COLLSEQ );
    assert( pOp[-1].opcode==OP_CollSeq );
    u.ag.ctx.pColl = pOp[-1].p4.pColl;
  }
  db->lastRowid = lastRowid;
  (*u.ag.ctx.pFunc->xFunc)(&u.ag.ctx, u.ag.n, u.ag.apVal); /* IMP: R-24505-23230 */
  lastRowid = db->lastRowid;

  /* If any auxiliary data functions have been called by this user function,
  ** immediately call the destructor for any non-static values.
  */
  if( u.ag.ctx.pVdbeFunc ){
    sqlite3VdbeDeleteAuxData(u.ag.ctx.pVdbeFunc, pOp->p1);
    pOp->p4.pVdbeFunc = u.ag.ctx.pVdbeFunc;
    pOp->p4type = P4_VDBEFUNC;
  }

  if( db->mallocFailed ){
    /* Even though a malloc() has failed, the implementation of the
    ** user function may have called an sqlite3_result_XXX() function
    ** to return a value. The following call releases any resources
    ** associated with such a value.
    */
    sqlite3VdbeMemRelease(&u.ag.ctx.s);
    goto no_mem;
  }










  /* If the function returned an error, throw an exception */
  if( u.ag.ctx.isError ){
    sqlite3SetString(&p->zErrMsg, db, "%s", sqlite3_value_text(&u.ag.ctx.s));
    rc = u.ag.ctx.isError;
  }

  /* Copy the result of the function into register P3 */
................................................................................
** This works just like the Lt opcode except that the jump is taken if
** the operands in registers P1 and P3 are not equal.  See the Lt opcode for
** additional information.
**
** If SQLITE_NULLEQ is set in P5 then the result of comparison is always either
** true or false and is never NULL.  If both operands are NULL then the result
** of comparison is false.  If either operand is NULL then the result is true.
** If neither operand is NULL the result is the same as it would be if
** the SQLITE_NULLEQ flag were omitted from P5.
*/
/* Opcode: Eq P1 P2 P3 P4 P5
**
** This works just like the Lt opcode except that the jump is taken if
** the operands in registers P1 and P3 are equal.
** See the Lt opcode for additional information.
**
** If SQLITE_NULLEQ is set in P5 then the result of comparison is always either
** true or false and is never NULL.  If both operands are NULL then the result
** of comparison is true.  If either operand is NULL then the result is false.
** If neither operand is NULL the result is the same as it would be if
** the SQLITE_NULLEQ flag were omitted from P5.
*/
/* Opcode: Le P1 P2 P3 P4 P5
**
** This works just like the Lt opcode except that the jump is taken if
** the content of register P3 is less than or equal to the content of
** register P1.  See the Lt opcode for additional information.
................................................................................
  u16 flags3;         /* Copy of initial value of pIn3->flags */
#endif /* local variables moved into u.ai */

  pIn1 = &aMem[pOp->p1];
  pIn3 = &aMem[pOp->p3];
  u.ai.flags1 = pIn1->flags;
  u.ai.flags3 = pIn3->flags;
  if( (u.ai.flags1 | u.ai.flags3)&MEM_Null ){
    /* One or both operands are NULL */
    if( pOp->p5 & SQLITE_NULLEQ ){
      /* If SQLITE_NULLEQ is set (which will only happen if the operator is
      ** OP_Eq or OP_Ne) then take the jump or not depending on whether
      ** or not both operands are null.
      */
      assert( pOp->opcode==OP_Eq || pOp->opcode==OP_Ne );
      u.ai.res = (u.ai.flags1 & u.ai.flags3 & MEM_Null)==0;
    }else{
      /* SQLITE_NULLEQ is clear and at least one operand is NULL,
      ** then the result is always NULL.
      ** The jump is taken if the SQLITE_JUMPIFNULL bit is set.
      */
      if( pOp->p5 & SQLITE_STOREP2 ){
        pOut = &aMem[pOp->p2];
................................................................................
    sqlite3VdbeMemSetInt64(pOut, ~sqlite3VdbeIntValue(pIn1));
  }
  break;
}

/* Opcode: If P1 P2 P3 * *
**
** Jump to P2 if the value in register P1 is true.  The value
** is considered true if it is numeric and non-zero.  If the value
** in P1 is NULL then take the jump if P3 is true.
*/
/* Opcode: IfNot P1 P2 P3 * *
**
** Jump to P2 if the value in register P1 is False.  The value
** is considered true if it has a numeric value of zero.  If the value
** in P1 is NULL then take the jump if P3 is true.
*/
case OP_If:                 /* jump, in1 */
case OP_IfNot: {            /* jump, in1 */
#if 0  /* local variables moved into u.al */
  int c;
................................................................................
      */
      sqlite3SetString(&p->zErrMsg, db, "cannot open savepoint - "
        "SQL statements in progress");
      rc = SQLITE_BUSY;
    }else{
      u.aq.nName = sqlite3Strlen30(u.aq.zName);

#ifndef SQLITE_OMIT_VIRTUALTABLE
      /* This call is Ok even if this savepoint is actually a transaction
      ** savepoint (and therefore should not prompt xSavepoint()) callbacks.
      ** If this is a transaction savepoint being opened, it is guaranteed
      ** that the db->aVTrans[] array is empty.  */
      assert( db->autoCommit==0 || db->nVTrans==0 );
      rc = sqlite3VtabSavepoint(db, SAVEPOINT_BEGIN,
                                db->nStatement+db->nSavepoint);
      if( rc!=SQLITE_OK ) goto abort_due_to_error;
#endif

      /* Create a new savepoint structure. */
      u.aq.pNew = sqlite3DbMallocRaw(db, sizeof(Savepoint)+u.aq.nName+1);
      if( u.aq.pNew ){
        u.aq.pNew->zName = (char *)&u.aq.pNew[1];
        memcpy(u.aq.pNew->zName, u.aq.zName, u.aq.nName+1);

................................................................................
    }
  }
  break;
}

/* Opcode: NotExists P1 P2 P3 * *
**
** Use the content of register P3 as an integer key.  If a record 
** with that key does not exist in table of P1, then jump to P2. 
** If the record does exist, then fall through.  The cursor is left 
** pointing to the record if it exists.
**
** The difference between this operation and NotFound is that this
** operation assumes the key is an integer and that P1 is a table whereas
** NotFound assumes key is a blob constructed from MakeRecord and
................................................................................
** The record number is not previously used as a key in the database
** table that cursor P1 points to.  The new record number is written
** written to register P2.
**
** If P3>0 then P3 is a register in the root frame of this VDBE that holds 
** the largest previously generated record number. No new record numbers are
** allowed to be less than this value. When this value reaches its maximum, 
** an SQLITE_FULL error is generated. The P3 register is updated with the '
** generated record number. This P3 mechanism is used to help implement the
** AUTOINCREMENT feature.
*/
case OP_NewRowid: {           /* out2-prerelease */
#if 0  /* local variables moved into u.be */
  i64 v;                 /* The new rowid */
  VdbeCursor *pC;        /* Cursor of table to get the new rowid */
................................................................................
  }
  u.bm.pC->rowidIsValid = 0;
  break;
}

/* Opcode: IdxInsert P1 P2 P3 * P5
**
** Register P2 holds an SQL index key made using the
** MakeRecord instructions.  This opcode writes that key
** into the index P1.  Data for the entry is nil.
**
** P3 is a flag that provides a hint to the b-tree layer that this
** insert is likely to be an append.
**
** This instruction only works for indices.  The equivalent instruction
................................................................................
**
** If tracing is enabled (by the sqlite3_trace()) interface, then
** the UTF-8 string contained in P4 is emitted on the trace callback.
*/
case OP_Trace: {
#if 0  /* local variables moved into u.cn */
  char *zTrace;
  char *z;
#endif /* local variables moved into u.cn */

  if( db->xTrace && (u.cn.zTrace = (pOp->p4.z ? pOp->p4.z : p->zSql))!=0 ){


    u.cn.z = sqlite3VdbeExpandSql(p, u.cn.zTrace);
    db->xTrace(db->pTraceArg, u.cn.z);
    sqlite3DbFree(db, u.cn.z);
  }
#ifdef SQLITE_DEBUG
  if( (db->flags & SQLITE_SqlTrace)!=0
   && (u.cn.zTrace = (pOp->p4.z ? pOp->p4.z : p->zSql))!=0
  ){
    sqlite3DebugPrintf("SQL-trace: %s\n", u.cn.zTrace);
  }
#endif /* SQLITE_DEBUG */

  break;
}
#endif


/* Opcode: Noop * * * * *
**
................................................................................
      ** always return an SQL NULL. This is useful because it means
      ** we can invoke OP_Column to fill in the vdbe cursors type 
      ** and offset cache without causing any IO.
      */
      sqlite3VdbeChangeP4(v, 3+flags, SQLITE_INT_TO_PTR(pTab->nCol+1),P4_INT32);
      sqlite3VdbeChangeP2(v, 7, pTab->nCol);
      if( !db->mallocFailed ){
        pParse->nVar = 1;
        pParse->nMem = 1;
        pParse->nTab = 1;
        sqlite3VdbeMakeReady(v, pParse);
      }
    }
   
    pBlob->flags = flags;
    pBlob->iCol = iCol;
    pBlob->db = db;
    sqlite3BtreeLeaveAll(db);
................................................................................
  z = pExpr->u.zToken;
  assert( z!=0 );
  assert( z[0]!=0 );
  if( z[1]==0 ){
    /* Wildcard of the form "?".  Assign the next variable number */
    assert( z[0]=='?' );
    pExpr->iColumn = (ynVar)(++pParse->nVar);
  }else{
    ynVar x = 0;
    u32 n = sqlite3Strlen30(z);
    if( z[0]=='?' ){
      /* Wildcard of the form "?nnn".  Convert "nnn" to an integer and
      ** use it as the variable number */
      i64 i;
      int bOk = 0==sqlite3Atoi64(&z[1], &i, n-1, SQLITE_UTF8);
      pExpr->iColumn = x = (ynVar)i;
      testcase( i==0 );
      testcase( i==1 );
      testcase( i==db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER]-1 );
      testcase( i==db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER] );
      if( bOk==0 || i<1 || i>db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER] ){
        sqlite3ErrorMsg(pParse, "variable number must be between ?1 and ?%d",
            db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER]);
        x = 0;
      }
      if( i>pParse->nVar ){
        pParse->nVar = (int)i;
      }
    }else{
      /* Wildcards like ":aaa", "$aaa" or "@aaa".  Reuse the same variable
      ** number as the prior appearance of the same name, or if the name
      ** has never appeared before, reuse the same variable number
      */
      ynVar i;


      for(i=0; i<pParse->nzVar; i++){


        if( pParse->azVar[i] && memcmp(pParse->azVar[i],z,n+1)==0 ){
          pExpr->iColumn = x = (ynVar)i+1;
          break;
        }
      }

      if( x==0 ) x = pExpr->iColumn = (ynVar)(++pParse->nVar);
    }
    if( x>0 ){

      if( x>pParse->nzVar ){
        char **a;
        a = sqlite3DbRealloc(db, pParse->azVar, x*sizeof(a[0]));
        if( a==0 ) return;  /* Error reported through db->mallocFailed */
        pParse->azVar = a;
        memset(&a[pParse->nzVar], 0, (x-pParse->nzVar)*sizeof(a[0]));

        pParse->nzVar = x;
      }
      if( z[0]!='?' || pParse->azVar[x-1]==0 ){
        sqlite3DbFree(db, pParse->azVar[x-1]);
        pParse->azVar[x-1] = sqlite3DbStrNDup(db, z, n);
      }
    }
  } 
  if( !pParse->nErr && pParse->nVar>db->aLimit[SQLITE_LIMIT_VARIABLE_NUMBER] ){
    sqlite3ErrorMsg(pParse, "too many SQL variables");
  }
}
................................................................................
#endif
    case TK_VARIABLE: {
      assert( !ExprHasProperty(pExpr, EP_IntValue) );
      assert( pExpr->u.zToken!=0 );
      assert( pExpr->u.zToken[0]!=0 );
      sqlite3VdbeAddOp2(v, OP_Variable, pExpr->iColumn, target);
      if( pExpr->u.zToken[1]!=0 ){
        assert( pExpr->u.zToken[0]=='?' 
             || strcmp(pExpr->u.zToken, pParse->azVar[pExpr->iColumn-1])==0 );
        sqlite3VdbeChangeP4(v, -1, pParse->azVar[pExpr->iColumn-1], P4_STATIC);
      }
      break;
    }
    case TK_REGISTER: {
      inReg = pExpr->iTable;
      break;
    }
................................................................................

  /* Drop the table and index from the internal schema.  */
  sqlite3VdbeAddOp4(v, OP_DropTable, iDb, 0, 0, pTab->zName, 0);

  /* Reload the table, index and permanent trigger schemas. */
  zWhere = sqlite3MPrintf(pParse->db, "tbl_name=%Q", zName);
  if( !zWhere ) return;
  sqlite3VdbeAddParseSchemaOp(v, iDb, zWhere);

#ifndef SQLITE_OMIT_TRIGGER
  /* Now, if the table is not stored in the temp database, reload any temp 
  ** triggers. Don't use IN(...) in case SQLITE_OMIT_SUBQUERY is defined. 
  */
  if( (zWhere=whereTempTriggers(pParse, pTab))!=0 ){
    sqlite3VdbeAddParseSchemaOp(v, 1, zWhere);
  }
#endif
}

/*
** Parameter zName is the name of a table that is about to be altered
** (either with ALTER TABLE ... RENAME TO or ALTER TABLE ... ADD COLUMN).
................................................................................
    FILE *trace = (db->flags & SQLITE_VdbeTrace)!=0 ? stdout : 0;
    sqlite3VdbeTrace(v, trace);
#endif
    assert( pParse->iCacheLevel==0 );  /* Disables and re-enables match */
    /* A minimum of one cursor is required if autoincrement is used
    *  See ticket [a696379c1f08866] */
    if( pParse->pAinc!=0 && pParse->nTab==0 ) pParse->nTab = 1;
    sqlite3VdbeMakeReady(v, pParse);


    pParse->rc = SQLITE_DONE;
    pParse->colNamesSet = 0;
  }else{
    pParse->rc = SQLITE_ERROR;
  }
  pParse->nTab = 0;
  pParse->nMem = 0;
................................................................................
          pDb->zName
        );
      }
    }
#endif

    /* Reparse everything to update our internal data structures */
    sqlite3VdbeAddParseSchemaOp(v, iDb,
               sqlite3MPrintf(db, "tbl_name='%q'", p->zName));
  }


  /* Add the table to the in-memory representation of the database.
  */
  if( db->init.busy ){
    Table *pOld;
................................................................................

    /* Fill the index with data and reparse the schema. Code an OP_Expire
    ** to invalidate all pre-compiled statements.
    */
    if( pTblName ){
      sqlite3RefillIndex(pParse, pIndex, iMem);
      sqlite3ChangeCookie(pParse, iDb);
      sqlite3VdbeAddParseSchemaOp(v, iDb,
         sqlite3MPrintf(db, "name='%q' AND type='index'", pIndex->zName));

      sqlite3VdbeAddOp1(v, OP_Expire, 0);
    }
  }

  /* When adding an index to the list of indices for a table, make
  ** sure all indices labeled OE_Replace come after all those labeled
  ** OE_Ignore.  This is necessary for the correct constraint check
................................................................................

    /* Delete the row */
#ifndef SQLITE_OMIT_VIRTUALTABLE
    if( IsVirtual(pTab) ){
      const char *pVTab = (const char *)sqlite3GetVTable(db, pTab);
      sqlite3VtabMakeWritable(pParse, pTab);
      sqlite3VdbeAddOp4(v, OP_VUpdate, 0, 1, iRowid, pVTab, P4_VTAB);
      sqlite3VdbeChangeP5(v, OE_Abort);
      sqlite3MayAbort(pParse);
    }else
#endif
    {
      int count = (pParse->nested==0);    /* True to count changes */
      sqlite3GenerateRowDelete(pParse, pTab, iCur, iRowid, count, pTrigger, OE_Default);
    }
................................................................................
      sqlite3VdbeAddOp2(v, OP_SCopy, regBase+nCol, regBase+j);
    }else{
      sqlite3VdbeAddOp3(v, OP_Column, iCur, idx, regBase+j);
      sqlite3ColumnDefault(v, pTab, idx, -1);
    }
  }
  if( doMakeRec ){
    const char *zAff;
    if( pTab->pSelect || (pParse->db->flags & SQLITE_IdxRealAsInt)!=0 ){
      zAff = 0;
    }else{
      zAff = sqlite3IndexAffinityStr(v, pIdx);
    }
    sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol+1, regOut);
    sqlite3VdbeChangeP4(v, -1, zAff, P4_TRANSIENT);
  }
  sqlite3ReleaseTempRange(pParse, regBase, nCol+1);
  return regBase;
}

/************** End of delete.c **********************************************/
/************** Begin file func.c ********************************************/
................................................................................
/*
** For LIKE and GLOB matching on EBCDIC machines, assume that every
** character is exactly one byte in size.  Also, all characters are
** able to participate in upper-case-to-lower-case mappings in EBCDIC
** whereas only characters less than 0x80 do in ASCII.
*/
#if defined(SQLITE_EBCDIC)
# define sqlite3Utf8Read(A,C)  (*(A++))
# define GlogUpperToLower(A)   A = sqlite3UpperToLower[A]
#else
# define GlogUpperToLower(A)   if( !((A)&~0x7f) ){ A = sqlite3UpperToLower[A]; }
#endif

static const struct compareInfo globInfo = { '*', '?', '[', 0 };
/* The correct SQL-92 behavior is for the LIKE operator to ignore
** case.  Thus  'a' LIKE 'A' would be true. */
static const struct compareInfo likeInfoNorm = { '%', '_',   0, 1 };
/* If SQLITE_CASE_SENSITIVE_LIKE is defined, then the LIKE operator
................................................................................
**
**         abc[*]xyz        Matches "abc*xyz" only
*/
static int patternCompare(
  const u8 *zPattern,              /* The glob pattern */
  const u8 *zString,               /* The string to compare against the glob */
  const struct compareInfo *pInfo, /* Information about how to do the compare */
  u32 esc                          /* The escape character */
){
  u32 c, c2;
  int invert;
  int seen;
  u8 matchOne = pInfo->matchOne;
  u8 matchAll = pInfo->matchAll;
  u8 matchSet = pInfo->matchSet;
  u8 noCase = pInfo->noCase; 
  int prevEscape = 0;     /* True if the previous character was 'escape' */
................................................................................
      }
      return 0;
    }else if( !prevEscape && c==matchOne ){
      if( sqlite3Utf8Read(zString, &zString)==0 ){
        return 0;
      }
    }else if( c==matchSet ){
      u32 prior_c = 0;
      assert( esc==0 );    /* This only occurs for GLOB, not LIKE */
      seen = 0;
      invert = 0;
      c = sqlite3Utf8Read(zString, &zString);
      if( c==0 ) return 0;
      c2 = sqlite3Utf8Read(zPattern, &zPattern);
      if( c2=='^' ){
................................................................................
*/
static void likeFunc(
  sqlite3_context *context, 
  int argc, 
  sqlite3_value **argv
){
  const unsigned char *zA, *zB;
  u32 escape = 0;
  int nPat;
  sqlite3 *db = sqlite3_context_db_handle(context);

  zB = sqlite3_value_text(argv[0]);
  zA = sqlite3_value_text(argv[1]);

  /* Limit the length of the LIKE or GLOB pattern to avoid problems
................................................................................
      for(i=0; i<nCol; i++){
        sqlite3VdbeAddOp2(v, OP_Copy, aiCol[i]+1+regData, regTemp+i);
      }
  
      /* If the parent table is the same as the child table, and we are about
      ** to increment the constraint-counter (i.e. this is an INSERT operation),
      ** then check if the row being inserted matches itself. If so, do not
      ** increment the constraint-counter. 
      **
      ** If any of the parent-key values are NULL, then the row cannot match 
      ** itself. So set JUMPIFNULL to make sure we do the OP_Found if any
      ** of the parent-key values are NULL (at this point it is known that
      ** none of the child key values are).
      */
      if( pTab==pFKey->pFrom && nIncr==1 ){
        int iJump = sqlite3VdbeCurrentAddr(v) + nCol + 1;
        for(i=0; i<nCol; i++){
          int iChild = aiCol[i]+1+regData;
          int iParent = pIdx->aiColumn[i]+1+regData;
          assert( aiCol[i]!=pTab->iPKey );
          if( pIdx->aiColumn[i]==pTab->iPKey ){
            /* The parent key is a composite key that includes the IPK column */
            iParent = regData;
          }
          sqlite3VdbeAddOp3(v, OP_Ne, iChild, iJump, iParent);
          sqlite3VdbeChangeP5(v, SQLITE_JUMPIFNULL);
        }
        sqlite3VdbeAddOp2(v, OP_Goto, 0, iOk);
      }
  
      sqlite3VdbeAddOp3(v, OP_MakeRecord, regTemp, nCol, regRec);
      sqlite3VdbeChangeP4(v, -1, sqlite3IndexAffinityStr(v,pIdx), P4_TRANSIENT);
      sqlite3VdbeAddOp4Int(v, OP_Found, iCur, iOk, regRec, 0);
................................................................................
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code used to implement the PRAGMA command.
*/





/*
** Interpret the given string as a safety level.  Return 0 for OFF,
** 1 for ON or NORMAL and 2 for FULL.  Return 1 for an empty or 
** unrecognized string argument.
**
** Note that the values returned are one less that the values that
** should be passed into sqlite3BtreeSetSafetyLevel().  The is done
................................................................................

/*
** Interpret the given string as a boolean value.
*/
SQLITE_PRIVATE u8 sqlite3GetBoolean(const char *z){
  return getSafetyLevel(z)&1;
}

/* The sqlite3GetBoolean() function is used by other modules but the
** remainder of this file is specific to PRAGMA processing.  So omit
** the rest of the file if PRAGMAs are omitted from the build.
*/
#if !defined(SQLITE_OMIT_PRAGMA)

/*
** Interpret the given string as a locking mode value.
*/
static int getLockingMode(const char *z){
  if( z ){
    if( 0==sqlite3StrICmp(z, "exclusive") ) return PAGER_LOCKINGMODE_EXCLUSIVE;
................................................................................
    z = sqlite3DbStrNDup(db, (char*)pAll->z, pAll->n);
    sqlite3NestedParse(pParse,
       "INSERT INTO %Q.%s VALUES('trigger',%Q,%Q,0,'CREATE TRIGGER %q')",
       db->aDb[iDb].zName, SCHEMA_TABLE(iDb), zName,
       pTrig->table, z);
    sqlite3DbFree(db, z);
    sqlite3ChangeCookie(pParse, iDb);
    sqlite3VdbeAddParseSchemaOp(v, iDb,
        sqlite3MPrintf(db, "type='trigger' AND name='%q'", zName));

  }

  if( db->init.busy ){
    Trigger *pLink = pTrig;
    Hash *pHash = &db->aDb[iDb].pSchema->trigHash;
    assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
    pTrig = sqlite3HashInsert(pHash, zName, sqlite3Strlen30(zName), pTrig);
................................................................................
  for(nIdx=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nIdx++){}
  if( nIdx>0 ){
    aRegIdx = sqlite3DbMallocRaw(db, sizeof(Index*) * nIdx );
    if( aRegIdx==0 ) goto update_cleanup;
  }
  for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
    int reg;
    if( hasFK || chngRowid ){
      reg = ++pParse->nMem;
    }else{
      reg = 0;
      for(i=0; i<pIdx->nColumn; i++){
        if( aXRef[pIdx->aiColumn[i]]>=0 ){
          reg = ++pParse->nMem;
          break;
................................................................................
    );
    sqlite3DbFree(db, zStmt);
    v = sqlite3GetVdbe(pParse);
    sqlite3ChangeCookie(pParse, iDb);

    sqlite3VdbeAddOp2(v, OP_Expire, 0, 0);
    zWhere = sqlite3MPrintf(db, "name='%q' AND type='table'", pTab->zName);
    sqlite3VdbeAddParseSchemaOp(v, iDb, zWhere);
    sqlite3VdbeAddOp4(v, OP_VCreate, iDb, 0, 0, 
                         pTab->zName, sqlite3Strlen30(pTab->zName) + 1);
  }

  /* If we are rereading the sqlite_master table create the in-memory
  ** record of the table. The xConnect() method is not called until
  ** the first time the virtual table is used in an SQL statement. This
................................................................................
      return i;
    }
#ifndef SQLITE_OMIT_BLOB_LITERAL
    case 'x': case 'X': {
      testcase( z[0]=='x' ); testcase( z[0]=='X' );
      if( z[1]=='\'' ){
        *tokenType = TK_BLOB;
        for(i=2; sqlite3Isxdigit(z[i]); i++){}
        if( z[i]!='\'' || i%2 ){
          *tokenType = TK_ILLEGAL;
          while( z[i] && z[i]!='\'' ){ i++; }
        }
        if( z[i] ) i++;

        return i;
      }
      /* Otherwise fall through to the next case */
    }
#endif
    default: {
      if( !IdChar(*z) ){
................................................................................
  if( pEngine==0 ){
    db->mallocFailed = 1;
    return SQLITE_NOMEM;
  }
  assert( pParse->pNewTable==0 );
  assert( pParse->pNewTrigger==0 );
  assert( pParse->nVar==0 );
  assert( pParse->nzVar==0 );

  assert( pParse->azVar==0 );
  enableLookaside = db->lookaside.bEnabled;
  if( db->lookaside.pStart ) db->lookaside.bEnabled = 1;
  while( !db->mallocFailed && zSql[i]!=0 ){
    assert( i>=0 );
    pParse->sLastToken.z = &zSql[i];
    pParse->sLastToken.n = sqlite3GetToken((unsigned char*)&zSql[i],&tokenType);
    i += pParse->sLastToken.n;
................................................................................
    ** structure built up in pParse->pNewTable. The calling code (see vtab.c)
    ** will take responsibility for freeing the Table structure.
    */
    sqlite3DeleteTable(db, pParse->pNewTable);
  }

  sqlite3DeleteTrigger(db, pParse->pNewTrigger);
  for(i=pParse->nzVar-1; i>=0; i--) sqlite3DbFree(db, pParse->azVar[i]);
  sqlite3DbFree(db, pParse->azVar);
  sqlite3DbFree(db, pParse->aAlias);
  while( pParse->pAinc ){
    AutoincInfo *p = pParse->pAinc;
    pParse->pAinc = p->pNext;
    sqlite3DbFree(db, p);
  }
  while( pParse->pZombieTab ){
................................................................................
      if( nOpt==3 && memcmp("vfs", zOpt, 3)==0 ){
        zVfs = zVal;
      }else{
        struct OpenMode {
          const char *z;
          int mode;
        } *aMode = 0;
        char *zModeType = 0;
        int mask = 0;
        int limit = 0;

        if( nOpt==5 && memcmp("cache", zOpt, 5)==0 ){
          static struct OpenMode aCacheMode[] = {
            { "shared",  SQLITE_OPEN_SHAREDCACHE },
            { "private", SQLITE_OPEN_PRIVATECACHE },
            { 0, 0 }
          };
................................................................................
      ppNew = va_arg(ap, void**);
      pFree = va_arg(ap, void*);
      if( sz ) *ppNew = sqlite3ScratchMalloc(sz);
      sqlite3ScratchFree(pFree);
      break;
    }

    /*   sqlite3_test_control(SQLITE_TESTCTRL_LOCALTIME_FAULT, int onoff);
    **
    ** If parameter onoff is non-zero, configure the wrappers so that all
    ** subsequent calls to localtime() and variants fail. If onoff is zero,
    ** undo this setting.
    */
    case SQLITE_TESTCTRL_LOCALTIME_FAULT: {
      sqlite3GlobalConfig.bLocaltimeFault = va_arg(ap, int);
      break;
    }

  }
  va_end(ap);
#endif /* SQLITE_OMIT_BUILTIN_TEST */
  return rc;
}

/*
................................................................................
** older data.
**
** TODO(shess) Provide a VACUUM type operation to clear out all
** deletions and duplications.  This would basically be a forced merge
** into a single segment.
*/







/************** Include fts3Int.h in the middle of fts3.c ********************/
/************** Begin file fts3Int.h *****************************************/
/*
** 2009 Nov 12
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
................................................................................
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
*/

#ifndef _FTSINT_H
#define _FTSINT_H

#if !defined(NDEBUG) && !defined(SQLITE_DEBUG) 
# define NDEBUG 1
#endif

/*
** FTS4 is really an extension for FTS3.  It is enabled using the
** SQLITE_ENABLE_FTS3 macro.  But to avoid confusion we also all
** the SQLITE_ENABLE_FTS4 macro to serve as an alisse for SQLITE_ENABLE_FTS3.
*/
#if defined(SQLITE_ENABLE_FTS4) && !defined(SQLITE_ENABLE_FTS3)
# define SQLITE_ENABLE_FTS3
#endif

#ifdef SQLITE_ENABLE_FTS3
/************** Include fts3_tokenizer.h in the middle of fts3Int.h **********/
/************** Begin file fts3_tokenizer.h **********************************/
/*
** 2006 July 10
**
** The author disclaims copyright to this source code.
**
................................................................................
/*
** Macro to return the number of elements in an array. SQLite has a
** similar macro called ArraySize(). Use a different name to avoid
** a collision when building an amalgamation with built-in FTS3.
*/
#define SizeofArray(X) ((int)(sizeof(X)/sizeof(X[0])))


#ifndef MIN
# define MIN(x,y) ((x)<(y)?(x):(y))
#endif

/*
** Maximum length of a varint encoded integer. The varint format is different
** from that used by SQLite, so the maximum length is 10, not 9.
*/
#define FTS3_VARINT_MAX 10

/*
** FTS4 virtual tables may maintain multiple indexes - one index of all terms
** in the document set and zero or more prefix indexes. All indexes are stored
** as one or more b+-trees in the %_segments and %_segdir tables. 
**
** It is possible to determine which index a b+-tree belongs to based on the
** value stored in the "%_segdir.level" column. Given this value L, the index
** that the b+-tree belongs to is (L<<10). In other words, all b+-trees with
** level values between 0 and 1023 (inclusive) belong to index 0, all levels
** between 1024 and 2047 to index 1, and so on.
**
** It is considered impossible for an index to use more than 1024 levels. In 
** theory though this may happen, but only after at least 
** (FTS3_MERGE_COUNT^1024) separate flushes of the pending-terms tables.
*/
#define FTS3_SEGDIR_MAXLEVEL      1024
#define FTS3_SEGDIR_MAXLEVEL_STR "1024"

/*
** The testcase() macro is only used by the amalgamation.  If undefined,
** make it a no-op.
*/
#ifndef testcase
# define testcase(X)
#endif
................................................................................

typedef struct Fts3Table Fts3Table;
typedef struct Fts3Cursor Fts3Cursor;
typedef struct Fts3Expr Fts3Expr;
typedef struct Fts3Phrase Fts3Phrase;
typedef struct Fts3PhraseToken Fts3PhraseToken;

typedef struct Fts3Doclist Fts3Doclist;
typedef struct Fts3SegFilter Fts3SegFilter;
typedef struct Fts3DeferredToken Fts3DeferredToken;
typedef struct Fts3SegReader Fts3SegReader;
typedef struct Fts3MultiSegReader Fts3MultiSegReader;

/*
** A connection to a fulltext index is an instance of the following
** structure. The xCreate and xConnect methods create an instance
** of this structure and xDestroy and xDisconnect free that instance.
** All other methods receive a pointer to the structure as one of their
** arguments.
................................................................................
  int nColumn;                    /* number of named columns in virtual table */
  char **azColumn;                /* column names.  malloced */
  sqlite3_tokenizer *pTokenizer;  /* tokenizer for inserts and queries */

  /* Precompiled statements used by the implementation. Each of these 
  ** statements is run and reset within a single virtual table API call. 
  */
  sqlite3_stmt *aStmt[27];

  char *zReadExprlist;
  char *zWriteExprlist;

  int nNodeSize;                  /* Soft limit for node size */
  u8 bHasStat;                    /* True if %_stat table exists */
  u8 bHasDocsize;                 /* True if %_docsize table exists */
  u8 bDescIdx;                    /* True if doclists are in reverse order */
  int nPgsz;                      /* Page size for host database */
  char *zSegmentsTbl;             /* Name of %_segments table */
  sqlite3_blob *pSegments;        /* Blob handle open on %_segments table */

  /* TODO: Fix the first paragraph of this comment.
  **
  ** The following hash table is used to buffer pending index updates during
  ** transactions. Variable nPendingData estimates the memory size of the 
  ** pending data, including hash table overhead, but not malloc overhead. 
  ** When nPendingData exceeds nMaxPendingData, the buffer is flushed 
  ** automatically. Variable iPrevDocid is the docid of the most recently
  ** inserted record.
  **
  ** A single FTS4 table may have multiple full-text indexes. For each index
  ** there is an entry in the aIndex[] array. Index 0 is an index of all the
  ** terms that appear in the document set. Each subsequent index in aIndex[]
  ** is an index of prefixes of a specific length.
  */
  int nIndex;                     /* Size of aIndex[] */
  struct Fts3Index {
    int nPrefix;                  /* Prefix length (0 for main terms index) */
    Fts3Hash hPending;            /* Pending terms table for this index */
  } *aIndex;
  int nMaxPendingData;            /* Max pending data before flush to disk */
  int nPendingData;               /* Current bytes of pending data */
  sqlite_int64 iPrevDocid;        /* Docid of most recently inserted document */


#if defined(SQLITE_DEBUG)
  /* State variables used for validating that the transaction control
  ** methods of the virtual table are called at appropriate times.  These
  ** values do not contribution to the FTS computation; they are used for
  ** verifying the SQLite core.
  */
................................................................................
  Fts3Expr *pExpr;                /* Parsed MATCH query string */
  int nPhrase;                    /* Number of matchable phrases in query */
  Fts3DeferredToken *pDeferred;   /* Deferred search tokens, if any */
  sqlite3_int64 iPrevId;          /* Previous id read from aDoclist */
  char *pNextId;                  /* Pointer into the body of aDoclist */
  char *aDoclist;                 /* List of docids for full-text queries */
  int nDoclist;                   /* Size of buffer at aDoclist */
  u8 bDesc;                       /* True to sort in descending order */
  int eEvalmode;                  /* An FTS3_EVAL_XX constant */
  int nRowAvg;                    /* Average size of database rows, in pages */
  sqlite3_int64 nDoc;             /* Documents in table */

  int isMatchinfoNeeded;          /* True when aMatchinfo[] needs filling in */
  u32 *aMatchinfo;                /* Information about most recent match */
  int nMatchinfo;                 /* Number of elements in aMatchinfo[] */
  char *zMatchinfo;               /* Matchinfo specification */
};

................................................................................
** indicating that all columns should be searched,
** then eSearch would be set to FTS3_FULLTEXT_SEARCH+4.
*/
#define FTS3_FULLSCAN_SEARCH 0    /* Linear scan of %_content table */
#define FTS3_DOCID_SEARCH    1    /* Lookup by rowid on %_content table */
#define FTS3_FULLTEXT_SEARCH 2    /* Full-text index search */


struct Fts3Doclist {
  char *aAll;                    /* Array containing doclist (or NULL) */
  int nAll;                      /* Size of a[] in bytes */
  char *pNextDocid;              /* Pointer to next docid */

  sqlite3_int64 iDocid;          /* Current docid (if pList!=0) */
  int bFreeList;                 /* True if pList should be sqlite3_free()d */
  char *pList;                   /* Pointer to position list following iDocid */
  int nList;                     /* Length of position list */
} doclist;

/*
** A "phrase" is a sequence of one or more tokens that must match in
** sequence.  A single token is the base case and the most common case.
** For a sequence of tokens contained in double-quotes (i.e. "one two three")
** nToken will be the number of tokens in the string.






*/
struct Fts3PhraseToken {
  char *z;                        /* Text of the token */
  int n;                          /* Number of bytes in buffer z */
  int isPrefix;                   /* True if token ends with a "*" character */


  /* Variables above this point are populated when the expression is
  ** parsed (by code in fts3_expr.c). Below this point the variables are
  ** used when evaluating the expression. */
  Fts3DeferredToken *pDeferred;   /* Deferred token object for this token */
  Fts3MultiSegReader *pSegcsr;    /* Segment-reader for this token */
};

struct Fts3Phrase {
  /* Cache of doclist for this phrase. */
  Fts3Doclist doclist;
  int bIncr;                 /* True if doclist is loaded incrementally */
  int iDoclistToken;

  /* Variables below this point are populated by fts3_expr.c when parsing 
  ** a MATCH expression. Everything above is part of the evaluation phase. 
  */
  int nToken;                /* Number of tokens in the phrase */
  int iColumn;               /* Index of column this phrase must match */

  Fts3PhraseToken aToken[1]; /* One entry for each token in the phrase */
};

/*
** A tree of these objects forms the RHS of a MATCH operator.
**
** If Fts3Expr.eType is FTSQUERY_PHRASE and isLoaded is true, then aDoclist 
** points to a malloced buffer, size nDoclist bytes, containing the results 
** of this phrase query in FTS3 doclist format. As usual, the initial 
** "Length" field found in doclists stored on disk is omitted from this 
** buffer.
**
** Variable aMI is used only for FTSQUERY_NEAR nodes to store the global
** matchinfo data. If it is not NULL, it points to an array of size nCol*3,
** where nCol is the number of columns in the queried FTS table. The array
** is populated as follows:
**
**   aMI[iCol*3 + 0] = Undefined
**   aMI[iCol*3 + 1] = Number of occurrences
**   aMI[iCol*3 + 2] = Number of rows containing at least one instance
**
** The aMI array is allocated using sqlite3_malloc(). It should be freed 
** when the expression node is.
*/
struct Fts3Expr {
  int eType;                 /* One of the FTSQUERY_XXX values defined below */
  int nNear;                 /* Valid if eType==FTSQUERY_NEAR */
  Fts3Expr *pParent;         /* pParent->pLeft==this or pParent->pRight==this */
  Fts3Expr *pLeft;           /* Left operand */
  Fts3Expr *pRight;          /* Right operand */
  Fts3Phrase *pPhrase;       /* Valid if eType==FTSQUERY_PHRASE */

  /* The following are used by the fts3_eval.c module. */
  sqlite3_int64 iDocid;      /* Current docid */
  u8 bEof;                   /* True this expression is at EOF already */
  u8 bStart;                 /* True if iDocid is valid */
  u8 bDeferred;              /* True if this expression is entirely deferred */



  u32 *aMI;
};

/*
** Candidate values for Fts3Query.eType. Note that the order of the first
** four values is in order of precedence when parsing expressions. For 
** example, the following:
**
................................................................................
/* fts3_write.c */
SQLITE_PRIVATE int sqlite3Fts3UpdateMethod(sqlite3_vtab*,int,sqlite3_value**,sqlite3_int64*);
SQLITE_PRIVATE int sqlite3Fts3PendingTermsFlush(Fts3Table *);
SQLITE_PRIVATE void sqlite3Fts3PendingTermsClear(Fts3Table *);
SQLITE_PRIVATE int sqlite3Fts3Optimize(Fts3Table *);
SQLITE_PRIVATE int sqlite3Fts3SegReaderNew(int, sqlite3_int64,
  sqlite3_int64, sqlite3_int64, const char *, int, Fts3SegReader**);
SQLITE_PRIVATE int sqlite3Fts3SegReaderPending(
  Fts3Table*,int,const char*,int,int,Fts3SegReader**);
SQLITE_PRIVATE void sqlite3Fts3SegReaderFree(Fts3SegReader *);

SQLITE_PRIVATE int sqlite3Fts3AllSegdirs(Fts3Table*, int, int, sqlite3_stmt **);
SQLITE_PRIVATE int sqlite3Fts3ReadLock(Fts3Table *);
SQLITE_PRIVATE int sqlite3Fts3ReadBlock(Fts3Table*, sqlite3_int64, char **, int*, int*);

SQLITE_PRIVATE int sqlite3Fts3SelectDoctotal(Fts3Table *, sqlite3_stmt **);
SQLITE_PRIVATE int sqlite3Fts3SelectDocsize(Fts3Table *, sqlite3_int64, sqlite3_stmt **);

SQLITE_PRIVATE void sqlite3Fts3FreeDeferredTokens(Fts3Cursor *);
SQLITE_PRIVATE int sqlite3Fts3DeferToken(Fts3Cursor *, Fts3PhraseToken *, int);
SQLITE_PRIVATE int sqlite3Fts3CacheDeferredDoclists(Fts3Cursor *);
SQLITE_PRIVATE void sqlite3Fts3FreeDeferredDoclists(Fts3Cursor *);

SQLITE_PRIVATE void sqlite3Fts3SegmentsClose(Fts3Table *);

/* Special values interpreted by sqlite3SegReaderCursor() */
#define FTS3_SEGCURSOR_PENDING        -1
#define FTS3_SEGCURSOR_ALL            -2

SQLITE_PRIVATE int sqlite3Fts3SegReaderStart(Fts3Table*, Fts3MultiSegReader*, Fts3SegFilter*);
SQLITE_PRIVATE int sqlite3Fts3SegReaderStep(Fts3Table *, Fts3MultiSegReader *);
SQLITE_PRIVATE void sqlite3Fts3SegReaderFinish(Fts3MultiSegReader *);

SQLITE_PRIVATE int sqlite3Fts3SegReaderCursor(
    Fts3Table *, int, int, const char *, int, int, int, Fts3MultiSegReader *);

/* Flags allowed as part of the 4th argument to SegmentReaderIterate() */
#define FTS3_SEGMENT_REQUIRE_POS   0x00000001
#define FTS3_SEGMENT_IGNORE_EMPTY  0x00000002
#define FTS3_SEGMENT_COLUMN_FILTER 0x00000004
#define FTS3_SEGMENT_PREFIX        0x00000008
#define FTS3_SEGMENT_SCAN          0x00000010
................................................................................
struct Fts3SegFilter {
  const char *zTerm;
  int nTerm;
  int iCol;
  int flags;
};

struct Fts3MultiSegReader {
  /* Used internally by sqlite3Fts3SegReaderXXX() calls */
  Fts3SegReader **apSegment;      /* Array of Fts3SegReader objects */
  int nSegment;                   /* Size of apSegment array */
  int nAdvance;                   /* How many seg-readers to advance */
  Fts3SegFilter *pFilter;         /* Pointer to filter object */
  char *aBuffer;                  /* Buffer to merge doclists in */
  int nBuffer;                    /* Allocated size of aBuffer[] in bytes */

  int iColFilter;                 /* If >=0, filter for this column */
  int bRestart;

  /* Used by fts3.c only. */

  int nCost;                      /* Cost of running iterator */
  int bLookup;                    /* True if a lookup of a single entry. */

  /* Output values. Valid only after Fts3SegReaderStep() returns SQLITE_ROW. */
  char *zTerm;                    /* Pointer to term buffer */
  int nTerm;                      /* Size of zTerm in bytes */
  char *aDoclist;                 /* Pointer to doclist buffer */
  int nDoclist;                   /* Size of aDoclist[] in bytes */
};
................................................................................

/* fts3.c */
SQLITE_PRIVATE int sqlite3Fts3PutVarint(char *, sqlite3_int64);
SQLITE_PRIVATE int sqlite3Fts3GetVarint(const char *, sqlite_int64 *);
SQLITE_PRIVATE int sqlite3Fts3GetVarint32(const char *, int *);
SQLITE_PRIVATE int sqlite3Fts3VarintLen(sqlite3_uint64);
SQLITE_PRIVATE void sqlite3Fts3Dequote(char *);
SQLITE_PRIVATE void sqlite3Fts3DoclistPrev(int,char*,int,char**,sqlite3_int64*,int*,u8*);


SQLITE_PRIVATE int sqlite3Fts3EvalPhraseStats(Fts3Cursor *, Fts3Expr *, u32 *);



/* fts3_tokenizer.c */
SQLITE_PRIVATE const char *sqlite3Fts3NextToken(const char *, int *);
SQLITE_PRIVATE int sqlite3Fts3InitHashTable(sqlite3 *, Fts3Hash *, const char *);
SQLITE_PRIVATE int sqlite3Fts3InitTokenizer(Fts3Hash *pHash, const char *, 
    sqlite3_tokenizer **, char **
);
................................................................................
SQLITE_PRIVATE int sqlite3Fts3ExprInitTestInterface(sqlite3 *db);
SQLITE_PRIVATE int sqlite3Fts3InitTerm(sqlite3 *db);
#endif

/* fts3_aux.c */
SQLITE_PRIVATE int sqlite3Fts3InitAux(sqlite3 *db);

SQLITE_PRIVATE int sqlite3Fts3TermSegReaderCursor(
  Fts3Cursor *pCsr,               /* Virtual table cursor handle */
  const char *zTerm,              /* Term to query for */
  int nTerm,                      /* Size of zTerm in bytes */
  int isPrefix,                   /* True for a prefix search */
  Fts3MultiSegReader **ppSegcsr   /* OUT: Allocated seg-reader cursor */
);

SQLITE_PRIVATE void sqlite3Fts3EvalPhraseCleanup(Fts3Phrase *);

SQLITE_PRIVATE int sqlite3Fts3EvalStart(Fts3Cursor *, Fts3Expr *, int);
SQLITE_PRIVATE int sqlite3Fts3EvalNext(Fts3Cursor *pCsr);

SQLITE_PRIVATE int sqlite3Fts3MsrIncrStart(
    Fts3Table*, Fts3MultiSegReader*, int, const char*, int);
SQLITE_PRIVATE int sqlite3Fts3MsrIncrNext(
    Fts3Table *, Fts3MultiSegReader *, sqlite3_int64 *, char **, int *);
SQLITE_PRIVATE char *sqlite3Fts3EvalPhrasePoslist(Fts3Cursor *, Fts3Expr *, int iCol); 
SQLITE_PRIVATE int sqlite3Fts3MsrOvfl(Fts3Cursor *, Fts3MultiSegReader *, int *);
SQLITE_PRIVATE int sqlite3Fts3MsrIncrRestart(Fts3MultiSegReader *pCsr);

SQLITE_PRIVATE int sqlite3Fts3DeferredTokenList(Fts3DeferredToken *, char **, int *);

#endif /* SQLITE_ENABLE_FTS3 */
#endif /* _FTSINT_H */

/************** End of fts3Int.h *********************************************/
/************** Continuing where we left off in fts3.c ***********************/
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

#if defined(SQLITE_ENABLE_FTS3) && !defined(SQLITE_CORE)
# define SQLITE_CORE 1
#endif


#ifndef SQLITE_CORE 
  SQLITE_EXTENSION_INIT1
#endif

/* 
................................................................................
  *pVal += iVal;
}

/*
** When this function is called, *pp points to the first byte following a
** varint that is part of a doclist (or position-list, or any other list
** of varints). This function moves *pp to point to the start of that varint,
** and sets *pVal by the varint value.
**
** Argument pStart points to the first byte of the doclist that the
** varint is part of.
*/
static void fts3GetReverseVarint(
  char **pp, 
  char *pStart, 
  sqlite3_int64 *pVal
){
  sqlite3_int64 iVal;
  char *p = *pp;

................................................................................
  ** interested in. So, unless the doclist is corrupt, the 0x80 bit is
  ** clear on character p[-1]. */
  for(p = (*pp)-2; p>=pStart && *p&0x80; p--);
  p++;
  *pp = p;

  sqlite3Fts3GetVarint(p, &iVal);
  *pVal = iVal;














}

/*
** The xDisconnect() virtual table method.
*/
static int fts3DisconnectMethod(sqlite3_vtab *pVtab){
  Fts3Table *p = (Fts3Table *)pVtab;
................................................................................
      rc = SQLITE_NOMEM;
    }else{
      rc = sqlite3_prepare(p->db, zSql, -1, &pStmt, 0);
      if( rc==SQLITE_OK ){
        sqlite3_step(pStmt);
        p->nPgsz = sqlite3_column_int(pStmt, 0);
        rc = sqlite3_finalize(pStmt);
      }else if( rc==SQLITE_AUTH ){
        p->nPgsz = 1024;
        rc = SQLITE_OK;
      }
    }
    assert( p->nPgsz>0 || rc!=SQLITE_OK );
    sqlite3_free(zSql);
    *pRc = rc;
  }
}
................................................................................
  fts3Appendf(pRc, &zRet, "?");
  for(i=0; i<p->nColumn; i++){
    fts3Appendf(pRc, &zRet, ",%s(?)", zFunction);
  }
  sqlite3_free(zFree);
  return zRet;
}

static int fts3GobbleInt(const char **pp, int *pnOut){
  const char *p = *pp;
  int nInt = 0;
  for(p=*pp; p[0]>='0' && p[0]<='9'; p++){
    nInt = nInt * 10 + (p[0] - '0');
  }
  if( p==*pp ) return SQLITE_ERROR;
  *pnOut = nInt;
  *pp = p;
  return SQLITE_OK;
}


static int fts3PrefixParameter(
  const char *zParam,             /* ABC in prefix=ABC parameter to parse */
  int *pnIndex,                   /* OUT: size of *apIndex[] array */
  struct Fts3Index **apIndex,     /* OUT: Array of indexes for this table */
  struct Fts3Index **apFree       /* OUT: Free this with sqlite3_free() */
){
  struct Fts3Index *aIndex;
  int nIndex = 1;

  if( zParam && zParam[0] ){
    const char *p;
    nIndex++;
    for(p=zParam; *p; p++){
      if( *p==',' ) nIndex++;
    }
  }

  aIndex = sqlite3_malloc(sizeof(struct Fts3Index) * nIndex);
  *apIndex = *apFree = aIndex;
  *pnIndex = nIndex;
  if( !aIndex ){
    return SQLITE_NOMEM;
  }

  memset(aIndex, 0, sizeof(struct Fts3Index) * nIndex);
  if( zParam ){
    const char *p = zParam;
    int i;
    for(i=1; i<nIndex; i++){
      int nPrefix;
      if( fts3GobbleInt(&p, &nPrefix) ) return SQLITE_ERROR;
      aIndex[i].nPrefix = nPrefix;
      p++;
    }
  }

  return SQLITE_OK;
}

/*
** This function is the implementation of both the xConnect and xCreate
** methods of the FTS3 virtual table.
**
** The argv[] array contains the following:
**
................................................................................
  int iCol;                       /* Column index */
  int nString = 0;                /* Bytes required to hold all column names */
  int nCol = 0;                   /* Number of columns in the FTS table */
  char *zCsr;                     /* Space for holding column names */
  int nDb;                        /* Bytes required to hold database name */
  int nName;                      /* Bytes required to hold table name */
  int isFts4 = (argv[0][3]=='4'); /* True for FTS4, false for FTS3 */

  const char **aCol;              /* Array of column names */
  sqlite3_tokenizer *pTokenizer = 0;        /* Tokenizer for this table */

  int nIndex;                     /* Size of aIndex[] array */
  struct Fts3Index *aIndex;       /* Array of indexes for this table */
  struct Fts3Index *aFree = 0;    /* Free this before returning */

  /* The results of parsing supported FTS4 key=value options: */
  int bNoDocsize = 0;             /* True to omit %_docsize table */
  int bDescIdx = 0;               /* True to store descending indexes */
  char *zPrefix = 0;              /* Prefix parameter value (or NULL) */
  char *zCompress = 0;            /* compress=? parameter (or NULL) */
  char *zUncompress = 0;          /* uncompress=? parameter (or NULL) */

  assert( strlen(argv[0])==4 );
  assert( (sqlite3_strnicmp(argv[0], "fts4", 4)==0 && isFts4)
       || (sqlite3_strnicmp(argv[0], "fts3", 4)==0 && !isFts4)
  );

  nDb = (int)strlen(argv[1]) + 1;
................................................................................
     && 0==sqlite3Fts3IsIdChar(z[8])
    ){
      rc = sqlite3Fts3InitTokenizer(pHash, &z[9], &pTokenizer, pzErr);
    }

    /* Check if it is an FTS4 special argument. */
    else if( isFts4 && fts3IsSpecialColumn(z, &nKey, &zVal) ){
      struct Fts4Option {
        const char *zOpt;
        int nOpt;
        char **pzVar;
      } aFts4Opt[] = {
        { "matchinfo",   9, 0 },            /* 0 -> MATCHINFO */
        { "prefix",      6, 0 },            /* 1 -> PREFIX */
        { "compress",    8, 0 },            /* 2 -> COMPRESS */
        { "uncompress", 10, 0 },            /* 3 -> UNCOMPRESS */
        { "order",       5, 0 }             /* 4 -> ORDER */
      };

      int iOpt;
      if( !zVal ){
        rc = SQLITE_NOMEM;

      }else{
        for(iOpt=0; iOpt<SizeofArray(aFts4Opt); iOpt++){
          struct Fts4Option *pOp = &aFts4Opt[iOpt];
          if( nKey==pOp->nOpt && !sqlite3_strnicmp(z, pOp->zOpt, pOp->nOpt) ){
            break;
          }



        }
        if( iOpt==SizeofArray(aFts4Opt) ){
          *pzErr = sqlite3_mprintf("unrecognized parameter: %s", z);
          rc = SQLITE_ERROR;
        }else{
          switch( iOpt ){
            case 0:               /* MATCHINFO */
              if( strlen(zVal)!=4 || sqlite3_strnicmp(zVal, "fts3", 4) ){
                *pzErr = sqlite3_mprintf("unrecognized matchinfo: %s", zVal);
                rc = SQLITE_ERROR;
              }

              bNoDocsize = 1;
              break;

            case 1:               /* PREFIX */
              sqlite3_free(zPrefix);
              zPrefix = zVal;
              zVal = 0;
              break;

            case 2:               /* COMPRESS */
              sqlite3_free(zCompress);
              zCompress = zVal;
              zVal = 0;

              break;

            case 3:               /* UNCOMPRESS */
              sqlite3_free(zUncompress);
              zUncompress = zVal;
              zVal = 0;

              break;

            case 4:               /* ORDER */
              if( (strlen(zVal)!=3 || sqlite3_strnicmp(zVal, "asc", 3)) 
               && (strlen(zVal)!=4 || sqlite3_strnicmp(zVal, "desc", 3)) 
              ){
                *pzErr = sqlite3_mprintf("unrecognized order: %s", zVal);
                rc = SQLITE_ERROR;
              }
              bDescIdx = (zVal[0]=='d' || zVal[0]=='D');
              break;
          }
        }
        sqlite3_free(zVal);
      }
    }

    /* Otherwise, the argument is a column name. */
    else {
      nString += (int)(strlen(z) + 1);
      aCol[nCol++] = z;
    }
................................................................................

  if( pTokenizer==0 ){
    rc = sqlite3Fts3InitTokenizer(pHash, "simple", &pTokenizer, pzErr);
    if( rc!=SQLITE_OK ) goto fts3_init_out;
  }
  assert( pTokenizer );

  rc = fts3PrefixParameter(zPrefix, &nIndex, &aIndex, &aFree);
  if( rc==SQLITE_ERROR ){
    assert( zPrefix );
    *pzErr = sqlite3_mprintf("error parsing prefix parameter: %s", zPrefix);
  }
  if( rc!=SQLITE_OK ) goto fts3_init_out;

  /* Allocate and populate the Fts3Table structure. */
  nByte = sizeof(Fts3Table) +                  /* Fts3Table */
          nCol * sizeof(char *) +              /* azColumn */
          nIndex * sizeof(struct Fts3Index) +  /* aIndex */
          nName +                              /* zName */
          nDb +                                /* zDb */
          nString;                             /* Space for azColumn strings */
  p = (Fts3Table*)sqlite3_malloc(nByte);
  if( p==0 ){
    rc = SQLITE_NOMEM;
    goto fts3_init_out;
................................................................................
  }
  memset(p, 0, nByte);
  p->db = db;
  p->nColumn = nCol;
  p->nPendingData = 0;
  p->azColumn = (char **)&p[1];
  p->pTokenizer = pTokenizer;

  p->nMaxPendingData = FTS3_MAX_PENDING_DATA;
  p->bHasDocsize = (isFts4 && bNoDocsize==0);
  p->bHasStat = isFts4;
  p->bDescIdx = bDescIdx;
  TESTONLY( p->inTransaction = -1 );
  TESTONLY( p->mxSavepoint = -1 );

  p->aIndex = (struct Fts3Index *)&p->azColumn[nCol];
  memcpy(p->aIndex, aIndex, sizeof(struct Fts3Index) * nIndex);
  p->nIndex = nIndex;
  for(i=0; i<nIndex; i++){
    fts3HashInit(&p->aIndex[i].hPending, FTS3_HASH_STRING, 1);
  }

  /* Fill in the zName and zDb fields of the vtab structure. */
  zCsr = (char *)&p->aIndex[nIndex];
  p->zName = zCsr;
  memcpy(zCsr, argv[2], nName);
  zCsr += nName;
  p->zDb = zCsr;
  memcpy(zCsr, argv[1], nDb);
  zCsr += nDb;

  /* Fill in the azColumn array */
  for(iCol=0; iCol<nCol; iCol++){
    char *z; 
    int n = 0;
    z = (char *)sqlite3Fts3NextToken(aCol[iCol], &n);
    memcpy(zCsr, z, n);
    zCsr[n] = '\0';
    sqlite3Fts3Dequote(zCsr);
    p->azColumn[iCol] = zCsr;
    zCsr += n+1;
    assert( zCsr <= &((char *)p)[nByte] );
................................................................................
  ** database. TODO: For xConnect(), it could verify that said tables exist.
  */
  if( isCreate ){
    rc = fts3CreateTables(p);
  }

  /* Figure out the page-size for the database. This is required in order to
  ** estimate the cost of loading large doclists from the database.  */


  fts3DatabasePageSize(&rc, p);
  p->nNodeSize = p->nPgsz-35;

  /* Declare the table schema to SQLite. */
  fts3DeclareVtab(&rc, p);

fts3_init_out:
  sqlite3_free(zPrefix);
  sqlite3_free(aFree);
  sqlite3_free(zCompress);
  sqlite3_free(zUncompress);
  sqlite3_free((void *)aCol);
  if( rc!=SQLITE_OK ){
    if( p ){
      fts3DisconnectMethod((sqlite3_vtab *)p);
    }else if( pTokenizer ){
      pTokenizer->pModule->xDestroy(pTokenizer);
    }
  }else{
    assert( p->pSegments==0 );
    *ppVTab = &p->base;
  }
  return rc;
}

/*
** The xConnect() and xCreate() methods for the virtual table. All the
................................................................................
    struct sqlite3_index_orderby *pOrder = &pInfo->aOrderBy[0];
    if( pOrder->iColumn<0 || pOrder->iColumn==p->nColumn+1 ){
      if( pOrder->desc ){
        pInfo->idxStr = "DESC";
      }else{
        pInfo->idxStr = "ASC";
      }

      pInfo->orderByConsumed = 1;
    }
  }

  assert( p->pSegments==0 );
  return SQLITE_OK;
}

/*
** Implementation of xOpen method.
*/
static int fts3OpenMethod(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCsr){
................................................................................
  Fts3Cursor *pCsr = (Fts3Cursor *)pCursor;
  assert( ((Fts3Table *)pCsr->base.pVtab)->pSegments==0 );
  sqlite3_finalize(pCsr->pStmt);
  sqlite3Fts3ExprFree(pCsr->pExpr);
  sqlite3Fts3FreeDeferredTokens(pCsr);
  sqlite3_free(pCsr->aDoclist);
  sqlite3_free(pCsr->aMatchinfo);
  assert( ((Fts3Table *)pCsr->base.pVtab)->pSegments==0 );
  sqlite3_free(pCsr);
  return SQLITE_OK;
}

/*
** Position the pCsr->pStmt statement so that it is on the row
** of the %_content table that contains the last match.  Return
** SQLITE_OK on success.  
*/
static int fts3CursorSeek(sqlite3_context *pContext, Fts3Cursor *pCsr){
  if( pCsr->isRequireSeek ){

    sqlite3_bind_int64(pCsr->pStmt, 1, pCsr->iPrevId);
    pCsr->isRequireSeek = 0;
    if( SQLITE_ROW==sqlite3_step(pCsr->pStmt) ){
      return SQLITE_OK;
    }else{
      int rc = sqlite3_reset(pCsr->pStmt);
      if( rc==SQLITE_OK ){
        /* If no row was found and no error has occured, then the %_content
        ** table is missing a row that is present in the full-text index.
................................................................................
  assert( !piLeaf2 || !piLeaf || rc!=SQLITE_OK || (*piLeaf<=*piLeaf2) );

  if( rc==SQLITE_OK && iHeight>1 ){
    char *zBlob = 0;              /* Blob read from %_segments table */
    int nBlob;                    /* Size of zBlob in bytes */

    if( piLeaf && piLeaf2 && (*piLeaf!=*piLeaf2) ){
      rc = sqlite3Fts3ReadBlock(p, *piLeaf, &zBlob, &nBlob, 0);
      if( rc==SQLITE_OK ){
        rc = fts3SelectLeaf(p, zTerm, nTerm, zBlob, nBlob, piLeaf, 0);
      }
      sqlite3_free(zBlob);
      piLeaf = 0;
      zBlob = 0;
    }

    if( rc==SQLITE_OK ){
      rc = sqlite3Fts3ReadBlock(p, piLeaf?*piLeaf:*piLeaf2, &zBlob, &nBlob, 0);
    }
    if( rc==SQLITE_OK ){
      rc = fts3SelectLeaf(p, zTerm, nTerm, zBlob, nBlob, piLeaf, piLeaf2);
    }
    sqlite3_free(zBlob);
  }

................................................................................
  }
  *p++ = 0x00;
  *pp = p;
  return 1;
}

/*
** Merge two position-lists as required by the NEAR operator. The argument
** position lists correspond to the left and right phrases of an expression 
** like:
**
**     "phrase 1" NEAR "phrase number 2"
**
** Position list *pp1 corresponds to the left-hand side of the NEAR 
** expression and *pp2 to the right. As usual, the indexes in the position 
** lists are the offsets of the last token in each phrase (tokens "1" and "2" 
** in the example above).
**
** The output position list - written to *pp - is a copy of *pp2 with those
** entries that are not sufficiently NEAR entries in *pp1 removed.
*/
static int fts3PoslistNearMerge(
  char **pp,                      /* Output buffer */
  char *aTmp,                     /* Temporary buffer space */
  int nRight,                     /* Maximum difference in token positions */
  int nLeft,                      /* Maximum difference in token positions */
  char **pp1,                     /* IN/OUT: Left input list */
  char **pp2                      /* IN/OUT: Right input list */
){
  char *p1 = *pp1;
  char *p2 = *pp2;







  char *pTmp1 = aTmp;
  char *pTmp2;
  char *aTmp2;
  int res = 1;

  fts3PoslistPhraseMerge(&pTmp1, nRight, 0, 0, pp1, pp2);
  aTmp2 = pTmp2 = pTmp1;
  *pp1 = p1;
  *pp2 = p2;
  fts3PoslistPhraseMerge(&pTmp2, nLeft, 1, 0, pp2, pp1);
  if( pTmp1!=aTmp && pTmp2!=aTmp2 ){
    fts3PoslistMerge(pp, &aTmp, &aTmp2);
  }else if( pTmp1!=aTmp ){
    fts3PoslistCopy(pp, &aTmp);
  }else if( pTmp2!=aTmp2 ){
    fts3PoslistCopy(pp, &aTmp2);
  }else{
    res = 0;
  }

  return res;
}


/* 

** A pointer to an instance of this structure is used as the context 
** argument to sqlite3Fts3SegReaderIterate()
*/






typedef struct TermSelect TermSelect;
struct TermSelect {
  int isReqPos;
  char *aaOutput[16];             /* Malloc'd output buffer */
  int anOutput[16];               /* Size of output in bytes */
};








static void fts3GetDeltaVarint3(
  char **pp, 
  char *pEnd, 
  int bDescIdx,
  sqlite3_int64 *pVal
){
  if( *pp>=pEnd ){
    *pp = 0;
  }else{
    sqlite3_int64 iVal;
    *pp += sqlite3Fts3GetVarint(*pp, &iVal);
    if( bDescIdx ){
      *pVal -= iVal;
    }else{
      *pVal += iVal;
    }
  }
}

static void fts3PutDeltaVarint3(
  char **pp,                      /* IN/OUT: Output pointer */
  int bDescIdx,                   /* True for descending docids */
  sqlite3_int64 *piPrev,          /* IN/OUT: Previous value written to list */
  int *pbFirst,                   /* IN/OUT: True after first int written */
  sqlite3_int64 iVal              /* Write this value to the list */
){
  sqlite3_int64 iWrite;
  if( bDescIdx==0 || *pbFirst==0 ){
    iWrite = iVal - *piPrev;
  }else{
    iWrite = *piPrev - iVal;
  }
  assert( *pbFirst || *piPrev==0 );
  assert( *pbFirst==0 || iWrite>0 );
  *pp += sqlite3Fts3PutVarint(*pp, iWrite);
  *piPrev = iVal;
  *pbFirst = 1;
}

#define COMPARE_DOCID(i1, i2) ((bDescIdx?-1:1) * (i1-i2))

static int fts3DoclistOrMerge(






  int bDescIdx,                   /* True if arguments are desc */
  char *a1, int n1,               /* First doclist */

  char *a2, int n2,               /* Second doclist */

  char **paOut, int *pnOut        /* OUT: Malloc'd doclist */
){
  sqlite3_int64 i1 = 0;
  sqlite3_int64 i2 = 0;
  sqlite3_int64 iPrev = 0;


  char *pEnd1 = &a1[n1];
  char *pEnd2 = &a2[n2];
  char *p1 = a1;
  char *p2 = a2;
  char *p;
  char *aOut;

  int bFirstOut = 0;








  *paOut = 0;
  *pnOut = 0;
  aOut = sqlite3_malloc(n1+n2);
  if( !aOut ) return SQLITE_NOMEM;



  p = aOut;
  fts3GetDeltaVarint3(&p1, pEnd1, 0, &i1);
  fts3GetDeltaVarint3(&p2, pEnd2, 0, &i2);




  while( p1 || p2 ){
    sqlite3_int64 iDiff = COMPARE_DOCID(i1, i2);

    if( p2 && p1 && iDiff==0 ){
      fts3PutDeltaVarint3(&p, bDescIdx, &iPrev, &bFirstOut, i1);
      fts3PoslistMerge(&p, &p1, &p2);
      fts3GetDeltaVarint3(&p1, pEnd1, bDescIdx, &i1);
      fts3GetDeltaVarint3(&p2, pEnd2, bDescIdx, &i2);
    }else if( !p2 || (p1 && iDiff<0) ){
      fts3PutDeltaVarint3(&p, bDescIdx, &iPrev, &bFirstOut, i1);
      fts3PoslistCopy(&p, &p1);
      fts3GetDeltaVarint3(&p1, pEnd1, bDescIdx, &i1);
    }else{
      fts3PutDeltaVarint3(&p, bDescIdx, &iPrev, &bFirstOut, i2);
      fts3PoslistCopy(&p, &p2);
      fts3GetDeltaVarint3(&p2, pEnd2, bDescIdx, &i2);
    }
  }























  *paOut = aOut;
  *pnOut = (p-aOut);
  return SQLITE_OK;

}

static void fts3DoclistPhraseMerge(
  int bDescIdx,                   /* True if arguments are desc */

  int nDist,                      /* Distance from left to right (1=adjacent) */
  char *aLeft, int nLeft,         /* Left doclist */
  char *aRight, int *pnRight      /* IN/OUT: Right/output doclist */
){
  sqlite3_int64 i1 = 0;


  sqlite3_int64 i2 = 0;



  sqlite3_int64 iPrev = 0;

















  char *pEnd1 = &aLeft[nLeft];
  char *pEnd2 = &aRight[*pnRight];
  char *p1 = aLeft;
  char *p2 = aRight;
  char *p;
  int bFirstOut = 0;
  char *aOut = aRight;






  assert( nDist>0 );

  p = aOut;
  fts3GetDeltaVarint3(&p1, pEnd1, 0, &i1);
  fts3GetDeltaVarint3(&p2, pEnd2, 0, &i2);


  while( p1 && p2 ){

    sqlite3_int64 iDiff = COMPARE_DOCID(i1, i2);
    if( iDiff==0 ){
      char *pSave = p;
      sqlite3_int64 iPrevSave = iPrev;

      int bFirstOutSave = bFirstOut;



      fts3PutDeltaVarint3(&p, bDescIdx, &iPrev, &bFirstOut, i1);
      if( 0==fts3PoslistPhraseMerge(&p, nDist, 0, 1, &p1, &p2) ){
        p = pSave;
        iPrev = iPrevSave;
        bFirstOut = bFirstOutSave;
      }

      fts3GetDeltaVarint3(&p1, pEnd1, bDescIdx, &i1);
      fts3GetDeltaVarint3(&p2, pEnd2, bDescIdx, &i2);
    }else if( iDiff<0 ){
      fts3PoslistCopy(0, &p1);
      fts3GetDeltaVarint3(&p1, pEnd1, bDescIdx, &i1);
    }else{
      fts3PoslistCopy(0, &p2);
      fts3GetDeltaVarint3(&p2, pEnd2, bDescIdx, &i2);
    }
  }



  *pnRight = p - aOut;
}






/*











** Merge all doclists in the TermSelect.aaOutput[] array into a single
** doclist stored in TermSelect.aaOutput[0]. If successful, delete all
** other doclists (except the aaOutput[0] one) and return SQLITE_OK.
**
** If an OOM error occurs, return SQLITE_NOMEM. In this case it is
** the responsibility of the caller to free any doclists left in the
** TermSelect.aaOutput[] array.
*/
static int fts3TermSelectMerge(Fts3Table *p, TermSelect *pTS){

  char *aOut = 0;
  int nOut = 0;
  int i;

  /* Loop through the doclists in the aaOutput[] array. Merge them all
  ** into a single doclist.
  */
................................................................................
  for(i=0; i<SizeofArray(pTS->aaOutput); i++){
    if( pTS->aaOutput[i] ){
      if( !aOut ){
        aOut = pTS->aaOutput[i];
        nOut = pTS->anOutput[i];
        pTS->aaOutput[i] = 0;
      }else{
        int nNew;
        char *aNew;

        int rc = fts3DoclistOrMerge(p->bDescIdx, 
            pTS->aaOutput[i], pTS->anOutput[i], aOut, nOut, &aNew, &nNew
        );
        if( rc!=SQLITE_OK ){
          sqlite3_free(aOut);
          return rc;
        }

        sqlite3_free(pTS->aaOutput[i]);
        sqlite3_free(aOut);
        pTS->aaOutput[i] = 0;
        aOut = aNew;
        nOut = nNew;
      }
    }
................................................................................

  UNUSED_PARAMETER(p);
  UNUSED_PARAMETER(zTerm);
  UNUSED_PARAMETER(nTerm);

  if( pTS->aaOutput[0]==0 ){
    /* If this is the first term selected, copy the doclist to the output
    ** buffer using memcpy(). */


    pTS->aaOutput[0] = sqlite3_malloc(nDoclist);
    pTS->anOutput[0] = nDoclist;
    if( pTS->aaOutput[0] ){
      memcpy(pTS->aaOutput[0], aDoclist, nDoclist);
    }else{
      return SQLITE_NOMEM;
    }
  }else{

    char *aMerge = aDoclist;
    int nMerge = nDoclist;
    int iOut;

    for(iOut=0; iOut<SizeofArray(pTS->aaOutput); iOut++){


      if( pTS->aaOutput[iOut]==0 ){
        assert( iOut>0 );
        pTS->aaOutput[iOut] = aMerge;
        pTS->anOutput[iOut] = nMerge;
        break;
      }else{
        char *aNew;
        int nNew;


        int rc = fts3DoclistOrMerge(p->bDescIdx, aMerge, nMerge, 
            pTS->aaOutput[iOut], pTS->anOutput[iOut], &aNew, &nNew

        );
        if( rc!=SQLITE_OK ){
          if( aMerge!=aDoclist ) sqlite3_free(aMerge);

          return rc;
        }




        if( aMerge!=aDoclist ) sqlite3_free(aMerge);
        sqlite3_free(pTS->aaOutput[iOut]);
        pTS->aaOutput[iOut] = 0;
  
        aMerge = aNew;
        nMerge = nNew;
        if( (iOut+1)==SizeofArray(pTS->aaOutput) ){
          pTS->aaOutput[iOut] = aMerge;
          pTS->anOutput[iOut] = nMerge;
        }
      }
    }
  }
  return SQLITE_OK;
}

/*
** Append SegReader object pNew to the end of the pCsr->apSegment[] array.
*/
static int fts3SegReaderCursorAppend(
  Fts3MultiSegReader *pCsr, 
  Fts3SegReader *pNew


){
  if( (pCsr->nSegment%16)==0 ){
    Fts3SegReader **apNew;
    int nByte = (pCsr->nSegment + 16)*sizeof(Fts3SegReader*);
    apNew = (Fts3SegReader **)sqlite3_realloc(pCsr->apSegment, nByte);


    if( !apNew ){




      sqlite3Fts3SegReaderFree(pNew);
      return SQLITE_NOMEM;








    }
    pCsr->apSegment = apNew;
  }
  pCsr->apSegment[pCsr->nSegment++] = pNew;
  return SQLITE_OK;
}

static int fts3SegReaderCursor(
  Fts3Table *p,                   /* FTS3 table handle */
  int iIndex,                     /* Index to search (from 0 to p->nIndex-1) */
  int iLevel,                     /* Level of segments to scan */
  const char *zTerm,              /* Term to query for */
  int nTerm,                      /* Size of zTerm in bytes */
  int isPrefix,                   /* True for a prefix search */
  int isScan,                     /* True to scan from zTerm to EOF */
  Fts3MultiSegReader *pCsr       /* Cursor object to populate */
){
  int rc = SQLITE_OK;
  int rc2;

  sqlite3_stmt *pStmt = 0;














  /* If iLevel is less than 0 and this is not a scan, include a seg-reader 

  ** for the pending-terms. If this is a scan, then this call must be being
  ** made by an fts4aux module, not an FTS table. In this case calling
  ** Fts3SegReaderPending might segfault, as the data structures used by 
  ** fts4aux are not completely populated. So it's easiest to filter these
  ** calls out here.  */
  if( iLevel<0 && p->aIndex ){
    Fts3SegReader *pSeg = 0;
    rc = sqlite3Fts3SegReaderPending(p, iIndex, zTerm, nTerm, isPrefix, &pSeg);
    if( rc==SQLITE_OK && pSeg ){









      rc = fts3SegReaderCursorAppend(pCsr, pSeg);
    }
  }

  if( iLevel!=FTS3_SEGCURSOR_PENDING ){
    if( rc==SQLITE_OK ){
      rc = sqlite3Fts3AllSegdirs(p, iIndex, iLevel, &pStmt);
    }

    while( rc==SQLITE_OK && SQLITE_ROW==(rc = sqlite3_step(pStmt)) ){
      Fts3SegReader *pSeg = 0;

      /* Read the values returned by the SELECT into local variables. */
      sqlite3_int64 iStartBlock = sqlite3_column_int64(pStmt, 1);
      sqlite3_int64 iLeavesEndBlock = sqlite3_column_int64(pStmt, 2);
      sqlite3_int64 iEndBlock = sqlite3_column_int64(pStmt, 3);
      int nRoot = sqlite3_column_bytes(pStmt, 4);
      char const *zRoot = sqlite3_column_blob(pStmt, 4);













      /* If zTerm is not NULL, and this segment is not stored entirely on its
      ** root node, the range of leaves scanned can be reduced. Do this. */
      if( iStartBlock && zTerm ){
        sqlite3_int64 *pi = (isPrefix ? &iLeavesEndBlock : 0);
        rc = fts3SelectLeaf(p, zTerm, nTerm, zRoot, nRoot, &iStartBlock, pi);
        if( rc!=SQLITE_OK ) goto finished;
        if( isPrefix==0 && isScan==0 ) iLeavesEndBlock = iStartBlock;
      }
 
      rc = sqlite3Fts3SegReaderNew(pCsr->nSegment+1, 
          iStartBlock, iLeavesEndBlock, iEndBlock, zRoot, nRoot, &pSeg
      );
      if( rc!=SQLITE_OK ) goto finished;
      rc = fts3SegReaderCursorAppend(pCsr, pSeg);

    }
  }

 finished:
  rc2 = sqlite3_reset(pStmt);
  if( rc==SQLITE_DONE ) rc = rc2;


  return rc;
}

/*
** Set up a cursor object for iterating through a full-text index or a 
** single level therein.
*/
SQLITE_PRIVATE int sqlite3Fts3SegReaderCursor(
  Fts3Table *p,                   /* FTS3 table handle */
  int iIndex,                     /* Index to search (from 0 to p->nIndex-1) */
  int iLevel,                     /* Level of segments to scan */
  const char *zTerm,              /* Term to query for */
  int nTerm,                      /* Size of zTerm in bytes */
  int isPrefix,                   /* True for a prefix search */
  int isScan,                     /* True to scan from zTerm to EOF */
  Fts3MultiSegReader *pCsr       /* Cursor object to populate */
){
  assert( iIndex>=0 && iIndex<p->nIndex );
  assert( iLevel==FTS3_SEGCURSOR_ALL
      ||  iLevel==FTS3_SEGCURSOR_PENDING 
      ||  iLevel>=0
  );
  assert( iLevel<FTS3_SEGDIR_MAXLEVEL );
  assert( FTS3_SEGCURSOR_ALL<0 && FTS3_SEGCURSOR_PENDING<0 );
  assert( isPrefix==0 || isScan==0 );

  /* "isScan" is only set to true by the ft4aux module, an ordinary
  ** full-text tables. */
  assert( isScan==0 || p->aIndex==0 );

  memset(pCsr, 0, sizeof(Fts3MultiSegReader));

  return fts3SegReaderCursor(
      p, iIndex, iLevel, zTerm, nTerm, isPrefix, isScan, pCsr
  );
}

static int fts3SegReaderCursorAddZero(
  Fts3Table *p,
  const char *zTerm,
  int nTerm,
  Fts3MultiSegReader *pCsr
){
  return fts3SegReaderCursor(p, 0, FTS3_SEGCURSOR_ALL, zTerm, nTerm, 0, 0,pCsr);
}


SQLITE_PRIVATE int sqlite3Fts3TermSegReaderCursor(
  Fts3Cursor *pCsr,               /* Virtual table cursor handle */
  const char *zTerm,              /* Term to query for */
  int nTerm,                      /* Size of zTerm in bytes */
  int isPrefix,                   /* True for a prefix search */
  Fts3MultiSegReader **ppSegcsr   /* OUT: Allocated seg-reader cursor */
){
  Fts3MultiSegReader *pSegcsr;   /* Object to allocate and return */
  int rc = SQLITE_NOMEM;          /* Return code */

  pSegcsr = sqlite3_malloc(sizeof(Fts3MultiSegReader));
  if( pSegcsr ){

    int i;
    int bFound = 0;               /* True once an index has been found */
    Fts3Table *p = (Fts3Table *)pCsr->base.pVtab;

    if( isPrefix ){
      for(i=1; bFound==0 && i<p->nIndex; i++){
        if( p->aIndex[i].nPrefix==nTerm ){
          bFound = 1;
          rc = sqlite3Fts3SegReaderCursor(
              p, i, FTS3_SEGCURSOR_ALL, zTerm, nTerm, 0, 0, pSegcsr);
          pSegcsr->bLookup = 1;
        }
      }

      for(i=1; bFound==0 && i<p->nIndex; i++){
        if( p->aIndex[i].nPrefix==nTerm+1 ){
          bFound = 1;
          rc = sqlite3Fts3SegReaderCursor(
              p, i, FTS3_SEGCURSOR_ALL, zTerm, nTerm, 1, 0, pSegcsr
          );
          if( rc==SQLITE_OK ){
            rc = fts3SegReaderCursorAddZero(p, zTerm, nTerm, pSegcsr);
          }
        }
      }
    }

    if( bFound==0 ){
      rc = sqlite3Fts3SegReaderCursor(
          p, 0, FTS3_SEGCURSOR_ALL, zTerm, nTerm, isPrefix, 0, pSegcsr
      );
      pSegcsr->bLookup = !isPrefix;
    }

  }

  *ppSegcsr = pSegcsr;
  return rc;
}

static void fts3SegReaderCursorFree(Fts3MultiSegReader *pSegcsr){
  sqlite3Fts3SegReaderFinish(pSegcsr);
  sqlite3_free(pSegcsr);
}

/*
** This function retreives the doclist for the specified term (or term
** prefix) from the database. 
................................................................................
  Fts3PhraseToken *pTok,          /* Token to query for */
  int iColumn,                    /* Column to query (or -ve for all columns) */
  int isReqPos,                   /* True to include position lists in output */
  int *pnOut,                     /* OUT: Size of buffer at *ppOut */
  char **ppOut                    /* OUT: Malloced result buffer */
){
  int rc;                         /* Return code */
  Fts3MultiSegReader *pSegcsr;   /* Seg-reader cursor for this term */
  TermSelect tsc;                 /* Context object for fts3TermSelectCb() */
  Fts3SegFilter filter;           /* Segment term filter configuration */

  pSegcsr = pTok->pSegcsr;
  memset(&tsc, 0, sizeof(TermSelect));
  tsc.isReqPos = isReqPos;

................................................................................
  ){
    rc = fts3TermSelectCb(p, (void *)&tsc, 
        pSegcsr->zTerm, pSegcsr->nTerm, pSegcsr->aDoclist, pSegcsr->nDoclist
    );
  }

  if( rc==SQLITE_OK ){
    rc = fts3TermSelectMerge(p, &tsc);
  }
  if( rc==SQLITE_OK ){
    *ppOut = tsc.aaOutput[0];
    *pnOut = tsc.anOutput[0];
  }else{
    int i;
    for(i=0; i<SizeofArray(tsc.aaOutput); i++){
................................................................................
      }
    }
  }

  return nDoc;
}

/*














































































































































































































































































































































































































































































































































































































































































** Advance the cursor to the next row in the %_content table that
** matches the search criteria.  For a MATCH search, this will be
** the next row that matches. For a full-table scan, this will be
** simply the next row in the %_content table.  For a docid lookup,
** this routine simply sets the EOF flag.
**
** Return SQLITE_OK if nothing goes wrong.  SQLITE_OK is returned
** even if we reach end-of-file.  The fts3EofMethod() will be called
** subsequently to determine whether or not an EOF was hit.
*/
static int fts3NextMethod(sqlite3_vtab_cursor *pCursor){
  int rc;

  Fts3Cursor *pCsr = (Fts3Cursor *)pCursor;




  if( pCsr->eSearch==FTS3_DOCID_SEARCH || pCsr->eSearch==FTS3_FULLSCAN_SEARCH ){
    if( SQLITE_ROW!=sqlite3_step(pCsr->pStmt) ){
      pCsr->isEof = 1;
      rc = sqlite3_reset(pCsr->pStmt);



    }else{




      pCsr->iPrevId = sqlite3_column_int64(pCsr->pStmt, 0);
      rc = SQLITE_OK;
    }

  }else{




    rc = sqlite3Fts3EvalNext((Fts3Cursor *)pCursor);
  }







  assert( ((Fts3Table *)pCsr->base.pVtab)->pSegments==0 );
  return rc;
}

/*
** This is the xFilter interface for the virtual table.  See
** the virtual table xFilter method documentation for additional
** information.
................................................................................
static int fts3FilterMethod(
  sqlite3_vtab_cursor *pCursor,   /* The cursor used for this query */
  int idxNum,                     /* Strategy index */
  const char *idxStr,             /* Unused */
  int nVal,                       /* Number of elements in apVal */
  sqlite3_value **apVal           /* Arguments for the indexing scheme */
){
  int rc;




  char *zSql;                     /* SQL statement used to access %_content */
  Fts3Table *p = (Fts3Table *)pCursor->pVtab;
  Fts3Cursor *pCsr = (Fts3Cursor *)pCursor;

  UNUSED_PARAMETER(idxStr);
  UNUSED_PARAMETER(nVal);

................................................................................

  /* In case the cursor has been used before, clear it now. */
  sqlite3_finalize(pCsr->pStmt);
  sqlite3_free(pCsr->aDoclist);
  sqlite3Fts3ExprFree(pCsr->pExpr);
  memset(&pCursor[1], 0, sizeof(Fts3Cursor)-sizeof(sqlite3_vtab_cursor));

  if( idxStr ){
    pCsr->bDesc = (idxStr[0]=='D');
  }else{
    pCsr->bDesc = p->bDescIdx;
  }
  pCsr->eSearch = (i16)idxNum;

  if( idxNum!=FTS3_DOCID_SEARCH && idxNum!=FTS3_FULLSCAN_SEARCH ){
    int iCol = idxNum-FTS3_FULLTEXT_SEARCH;
    const char *zQuery = (const char *)sqlite3_value_text(apVal[0]);

    if( zQuery==0 && sqlite3_value_type(apVal[0])!=SQLITE_NULL ){
      return SQLITE_NOMEM;
    }

    rc = sqlite3Fts3ExprParse(p->pTokenizer, p->azColumn, p->nColumn, 
        iCol, zQuery, -1, &pCsr->pExpr
    );
    if( rc!=SQLITE_OK ){
      if( rc==SQLITE_ERROR ){
        static const char *zErr = "malformed MATCH expression: [%s]";
        p->base.zErrMsg = sqlite3_mprintf(zErr, zQuery);
      }
      return rc;
    }

    rc = sqlite3Fts3ReadLock(p);
    if( rc!=SQLITE_OK ) return rc;

    rc = sqlite3Fts3EvalStart(pCsr, pCsr->pExpr, 1);

    sqlite3Fts3SegmentsClose(p);
    if( rc!=SQLITE_OK ) return rc;
    pCsr->pNextId = pCsr->aDoclist;
    pCsr->iPrevId = 0;
  }

  /* Compile a SELECT statement for this cursor. For a full-table-scan, the
  ** statement loops through all rows of the %_content table. For a
  ** full-text query or docid lookup, the statement retrieves a single
  ** row by docid.
  */
  if( idxNum==FTS3_FULLSCAN_SEARCH ){
    const char *zSort = (pCsr->bDesc ? "DESC" : "ASC");
    const char *zTmpl = "SELECT %s FROM %Q.'%q_content' AS x ORDER BY docid %s";
    zSql = sqlite3_mprintf(zTmpl, p->zReadExprlist, p->zDb, p->zName, zSort);



  }else{
    const char *zTmpl = "SELECT %s FROM %Q.'%q_content' AS x WHERE docid = ?";
    zSql = sqlite3_mprintf(zTmpl, p->zReadExprlist, p->zDb, p->zName);
  }
  if( !zSql ) return SQLITE_NOMEM;
  rc = sqlite3_prepare_v2(p->db, zSql, -1, &pCsr->pStmt, 0);
  sqlite3_free(zSql);
  if( rc!=SQLITE_OK ) return rc;

  if( idxNum==FTS3_DOCID_SEARCH ){
    rc = sqlite3_bind_value(pCsr->pStmt, 1, apVal[0]);




    if( rc!=SQLITE_OK ) return rc;





  }








  return fts3NextMethod(pCursor);
}

/* 
** This is the xEof method of the virtual table. SQLite calls this 
** routine to find out if it has reached the end of a result set.
*/
................................................................................
** This is the xRowid method. The SQLite core calls this routine to
** retrieve the rowid for the current row of the result set. fts3
** exposes %_content.docid as the rowid for the virtual table. The
** rowid should be written to *pRowid.
*/
static int fts3RowidMethod(sqlite3_vtab_cursor *pCursor, sqlite_int64 *pRowid){
  Fts3Cursor *pCsr = (Fts3Cursor *) pCursor;

  *pRowid = pCsr->iPrevId;








  return SQLITE_OK;
}

/* 
** This is the xColumn method, called by SQLite to request a value from
** the row that the supplied cursor currently points to.
*/
static int fts3ColumnMethod(
  sqlite3_vtab_cursor *pCursor,   /* Cursor to retrieve value from */
  sqlite3_context *pContext,      /* Context for sqlite3_result_xxx() calls */
  int iCol                        /* Index of column to read value from */
){
  int rc = SQLITE_OK;             /* Return Code */
  Fts3Cursor *pCsr = (Fts3Cursor *) pCursor;
  Fts3Table *p = (Fts3Table *)pCursor->pVtab;

  /* The column value supplied by SQLite must be in range. */
  assert( iCol>=0 && iCol<=p->nColumn+1 );

  if( iCol==p->nColumn+1 ){
    /* This call is a request for the "docid" column. Since "docid" is an 
    ** alias for "rowid", use the xRowid() method to obtain the value.
    */


    sqlite3_result_int64(pContext, pCsr->iPrevId);
  }else if( iCol==p->nColumn ){
    /* The extra column whose name is the same as the table.
    ** Return a blob which is a pointer to the cursor.
    */
    sqlite3_result_blob(pContext, &pCsr, sizeof(pCsr), SQLITE_TRANSIENT);

  }else{
    rc = fts3CursorSeek(0, pCsr);
    if( rc==SQLITE_OK ){
      sqlite3_result_value(pContext, sqlite3_column_value(pCsr->pStmt, iCol+1));
    }
  }

  assert( ((Fts3Table *)pCsr->base.pVtab)->pSegments==0 );
  return rc;
}

/* 
** This function is the implementation of the xUpdate callback used by 
** FTS3 virtual tables. It is invoked by SQLite each time a row is to be
** inserted, updated or deleted.
................................................................................
  return rc;
}

/*
** Implementation of xBegin() method. This is a no-op.
*/
static int fts3BeginMethod(sqlite3_vtab *pVtab){

  TESTONLY( Fts3Table *p = (Fts3Table*)pVtab );
  UNUSED_PARAMETER(pVtab);
  assert( p->pSegments==0 );
  assert( p->nPendingData==0 );
  assert( p->inTransaction!=1 );
  TESTONLY( p->inTransaction = 1 );
  TESTONLY( p->mxSavepoint = -1; );
  return SQLITE_OK;
}

/*
** Implementation of xCommit() method. This is a no-op. The contents of
** the pending-terms hash-table have already been flushed into the database
** by fts3SyncMethod().
*/
static int fts3CommitMethod(sqlite3_vtab *pVtab){

  TESTONLY( Fts3Table *p = (Fts3Table*)pVtab );
  UNUSED_PARAMETER(pVtab);
  assert( p->nPendingData==0 );
  assert( p->inTransaction!=0 );
  assert( p->pSegments==0 );
  TESTONLY( p->inTransaction = 0 );
  TESTONLY( p->mxSavepoint = -1; );
  return SQLITE_OK;
}

/*
** Implementation of xRollback(). Discard the contents of the pending-terms
................................................................................
  Fts3Table *p = (Fts3Table*)pVtab;
  sqlite3Fts3PendingTermsClear(p);
  assert( p->inTransaction!=0 );
  TESTONLY( p->inTransaction = 0 );
  TESTONLY( p->mxSavepoint = -1; );
  return SQLITE_OK;
}































/*
** When called, *ppPoslist must point to the byte immediately following the
** end of a position-list. i.e. ( (*ppPoslist)[-1]==POS_END ). This function
** moves *ppPoslist so that it instead points to the first byte of the
** same position list.
*/
static void fts3ReversePoslist(char *pStart, char **ppPoslist){
  char *p = &(*ppPoslist)[-2];
  char c;

  while( p>pStart && (c=*p--)==0 );
  while( p>pStart && (*p & 0x80) | c ){ 
    c = *p--; 
  }
  if( p>pStart ){ p = &p[2]; }
  while( *p++&0x80 );
  *ppPoslist = p;
}











































































/*
** Helper function used by the implementation of the overloaded snippet(),
** offsets() and optimize() SQL functions.
**
** If the value passed as the third argument is a blob of size
** sizeof(Fts3Cursor*), then the blob contents are copied to the 
** output variable *ppCsr and SQLITE_OK is returned. Otherwise, an error
................................................................................
    "ALTER TABLE %Q.'%q_segdir'   RENAME TO '%q_segdir';",
    p->zDb, p->zName, zName
  );
  return rc;
}

static int fts3SavepointMethod(sqlite3_vtab *pVtab, int iSavepoint){

  UNUSED_PARAMETER(iSavepoint);
  assert( ((Fts3Table *)pVtab)->inTransaction );
  assert( ((Fts3Table *)pVtab)->mxSavepoint < iSavepoint );
  TESTONLY( ((Fts3Table *)pVtab)->mxSavepoint = iSavepoint );

  return fts3SyncMethod(pVtab);
}
static int fts3ReleaseMethod(sqlite3_vtab *pVtab, int iSavepoint){
  TESTONLY( Fts3Table *p = (Fts3Table*)pVtab );
  UNUSED_PARAMETER(iSavepoint);
  UNUSED_PARAMETER(pVtab);
  assert( p->inTransaction );
  assert( p->mxSavepoint >= iSavepoint );
................................................................................
  const sqlite3_api_routines *pApi
){
  SQLITE_EXTENSION_INIT2(pApi)
  return sqlite3Fts3Init(db);
}
#endif


/*
** Allocate an Fts3MultiSegReader for each token in the expression headed
** by pExpr. 
**
** An Fts3SegReader object is a cursor that can seek or scan a range of
** entries within a single segment b-tree. An Fts3MultiSegReader uses multiple
** Fts3SegReader objects internally to provide an interface to seek or scan
** within the union of all segments of a b-tree. Hence the name.
**
** If the allocated Fts3MultiSegReader just seeks to a single entry in a
** segment b-tree (if the term is not a prefix or it is a prefix for which
** there exists prefix b-tree of the right length) then it may be traversed
** and merged incrementally. Otherwise, it has to be merged into an in-memory 
** doclist and then traversed.
*/
static void fts3EvalAllocateReaders(
  Fts3Cursor *pCsr, 
  Fts3Expr *pExpr, 
  int *pnToken,                   /* OUT: Total number of tokens in phrase. */
  int *pnOr,                      /* OUT: Total number of OR nodes in expr. */
  int *pRc
){
  if( pExpr && SQLITE_OK==*pRc ){
    if( pExpr->eType==FTSQUERY_PHRASE ){
      int i;
      int nToken = pExpr->pPhrase->nToken;
      *pnToken += nToken;
      for(i=0; i<nToken; i++){
        Fts3PhraseToken *pToken = &pExpr->pPhrase->aToken[i];
        int rc = sqlite3Fts3TermSegReaderCursor(pCsr, 
            pToken->z, pToken->n, pToken->isPrefix, &pToken->pSegcsr
        );
        if( rc!=SQLITE_OK ){
          *pRc = rc;
          return;
        }
      }
      assert( pExpr->pPhrase->iDoclistToken==0 );
      pExpr->pPhrase->iDoclistToken = -1;
    }else{
      *pnOr += (pExpr->eType==FTSQUERY_OR);
      fts3EvalAllocateReaders(pCsr, pExpr->pLeft, pnToken, pnOr, pRc);
      fts3EvalAllocateReaders(pCsr, pExpr->pRight, pnToken, pnOr, pRc);
    }
  }
}

static void fts3EvalPhraseMergeToken(
  Fts3Table *pTab,
  Fts3Phrase *p,
  int iToken,
  char *pList,
  int nList
){
  assert( iToken!=p->iDoclistToken );

  if( pList==0 ){
    sqlite3_free(p->doclist.aAll);
    p->doclist.aAll = 0;
    p->doclist.nAll = 0;
  }

  else if( p->iDoclistToken<0 ){
    p->doclist.aAll = pList;
    p->doclist.nAll = nList;
  }

  else if( p->doclist.aAll==0 ){
    sqlite3_free(pList);
  }

  else {
    char *pLeft;
    char *pRight;
    int nLeft;
    int nRight;
    int nDiff;

    if( p->iDoclistToken<iToken ){
      pLeft = p->doclist.aAll;
      nLeft = p->doclist.nAll;
      pRight = pList;
      nRight = nList;
      nDiff = iToken - p->iDoclistToken;
    }else{
      pRight = p->doclist.aAll;
      nRight = p->doclist.nAll;
      pLeft = pList;
      nLeft = nList;
      nDiff = p->iDoclistToken - iToken;
    }

    fts3DoclistPhraseMerge(pTab->bDescIdx, nDiff, pLeft, nLeft, pRight,&nRight);
    sqlite3_free(pLeft);
    p->doclist.aAll = pRight;
    p->doclist.nAll = nRight;
  }

  if( iToken>p->iDoclistToken ) p->iDoclistToken = iToken;
}

static int fts3EvalPhraseLoad(
  Fts3Cursor *pCsr, 
  Fts3Phrase *p
){
  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
  int iToken;
  int rc = SQLITE_OK;

  for(iToken=0; rc==SQLITE_OK && iToken<p->nToken; iToken++){
    Fts3PhraseToken *pToken = &p->aToken[iToken];
    assert( pToken->pDeferred==0 || pToken->pSegcsr==0 );

    if( pToken->pSegcsr ){
      int nThis = 0;
      char *pThis = 0;
      rc = fts3TermSelect(pTab, pToken, p->iColumn, 1, &nThis, &pThis);
      if( rc==SQLITE_OK ){
        fts3EvalPhraseMergeToken(pTab, p, iToken, pThis, nThis);
      }
    }
    assert( pToken->pSegcsr==0 );
  }

  return rc;
}

static int fts3EvalDeferredPhrase(Fts3Cursor *pCsr, Fts3Phrase *pPhrase){
  int iToken;
  int rc = SQLITE_OK;

  int nMaxUndeferred = pPhrase->iDoclistToken;
  char *aPoslist = 0;
  int nPoslist = 0;
  int iPrev = -1;

  assert( pPhrase->doclist.bFreeList==0 );

  for(iToken=0; rc==SQLITE_OK && iToken<pPhrase->nToken; iToken++){
    Fts3PhraseToken *pToken = &pPhrase->aToken[iToken];
    Fts3DeferredToken *pDeferred = pToken->pDeferred;

    if( pDeferred ){
      char *pList;
      int nList;
      rc = sqlite3Fts3DeferredTokenList(pDeferred, &pList, &nList);
      if( rc!=SQLITE_OK ) return rc;

      if( pList==0 ){
        sqlite3_free(aPoslist);
        pPhrase->doclist.pList = 0;
        pPhrase->doclist.nList = 0;
        return SQLITE_OK;

      }else if( aPoslist==0 ){
        aPoslist = pList;
        nPoslist = nList;

      }else{
        char *aOut = pList;
        char *p1 = aPoslist;
        char *p2 = aOut;

        assert( iPrev>=0 );
        fts3PoslistPhraseMerge(&aOut, iToken-iPrev, 0, 1, &p1, &p2);
        sqlite3_free(aPoslist);
        aPoslist = pList;
        nPoslist = aOut - aPoslist;
        if( nPoslist==0 ){
          sqlite3_free(aPoslist);
          pPhrase->doclist.pList = 0;
          pPhrase->doclist.nList = 0;
          return SQLITE_OK;
        }
      }
      iPrev = iToken;
    }
  }

  if( iPrev>=0 ){
    if( nMaxUndeferred<0 ){
      pPhrase->doclist.pList = aPoslist;
      pPhrase->doclist.nList = nPoslist;
      pPhrase->doclist.iDocid = pCsr->iPrevId;
      pPhrase->doclist.bFreeList = 1;
    }else{
      int nDistance;
      char *p1;
      char *p2;
      char *aOut;

      if( nMaxUndeferred>iPrev ){
        p1 = aPoslist;
        p2 = pPhrase->doclist.pList;
        nDistance = nMaxUndeferred - iPrev;
      }else{
        p1 = pPhrase->doclist.pList;
        p2 = aPoslist;
        nDistance = iPrev - nMaxUndeferred;
      }

      aOut = (char *)sqlite3_malloc(nPoslist+8);
      if( !aOut ){
        sqlite3_free(aPoslist);
        return SQLITE_NOMEM;
      }
      
      pPhrase->doclist.pList = aOut;
      if( fts3PoslistPhraseMerge(&aOut, nDistance, 0, 1, &p1, &p2) ){
        pPhrase->doclist.bFreeList = 1;
        pPhrase->doclist.nList = (aOut - pPhrase->doclist.pList);
      }else{
        sqlite3_free(aOut);
        pPhrase->doclist.pList = 0;
        pPhrase->doclist.nList = 0;
      }
      sqlite3_free(aPoslist);
    }
  }

  return SQLITE_OK;
}

/*
** This function is called for each Fts3Phrase in a full-text query 
** expression to initialize the mechanism for returning rows. Once this
** function has been called successfully on an Fts3Phrase, it may be
** used with fts3EvalPhraseNext() to iterate through the matching docids.
*/
static int fts3EvalPhraseStart(Fts3Cursor *pCsr, int bOptOk, Fts3Phrase *p){
  int rc;
  Fts3PhraseToken *pFirst = &p->aToken[0];
  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;

  if( pCsr->bDesc==pTab->bDescIdx 
   && bOptOk==1 
   && p->nToken==1 
   && pFirst->pSegcsr 
   && pFirst->pSegcsr->bLookup 
  ){
    /* Use the incremental approach. */
    int iCol = (p->iColumn >= pTab->nColumn ? -1 : p->iColumn);
    rc = sqlite3Fts3MsrIncrStart(
        pTab, pFirst->pSegcsr, iCol, pFirst->z, pFirst->n);
    p->bIncr = 1;

  }else{
    /* Load the full doclist for the phrase into memory. */
    rc = fts3EvalPhraseLoad(pCsr, p);
    p->bIncr = 0;
  }

  assert( rc!=SQLITE_OK || p->nToken<1 || p->aToken[0].pSegcsr==0 || p->bIncr );
  return rc;
}

/*
** This function is used to iterate backwards (from the end to start) 
** through doclists.
*/
SQLITE_PRIVATE void sqlite3Fts3DoclistPrev(
  int bDescIdx,                   /* True if the doclist is desc */
  char *aDoclist,                 /* Pointer to entire doclist */
  int nDoclist,                   /* Length of aDoclist in bytes */
  char **ppIter,                  /* IN/OUT: Iterator pointer */
  sqlite3_int64 *piDocid,         /* IN/OUT: Docid pointer */
  int *pnList,                    /* IN/OUT: List length pointer */
  u8 *pbEof                       /* OUT: End-of-file flag */
){
  char *p = *ppIter;

  assert( nDoclist>0 );
  assert( *pbEof==0 );
  assert( p || *piDocid==0 );
  assert( !p || (p>aDoclist && p<&aDoclist[nDoclist]) );

  if( p==0 ){
    sqlite3_int64 iDocid = 0;
    char *pNext = 0;
    char *pDocid = aDoclist;
    char *pEnd = &aDoclist[nDoclist];
    int iMul = 1;

    while( pDocid<pEnd ){
      sqlite3_int64 iDelta;
      pDocid += sqlite3Fts3GetVarint(pDocid, &iDelta);
      iDocid += (iMul * iDelta);
      pNext = pDocid;
      fts3PoslistCopy(0, &pDocid);
      while( pDocid<pEnd && *pDocid==0 ) pDocid++;
      iMul = (bDescIdx ? -1 : 1);
    }

    *pnList = pEnd - pNext;
    *ppIter = pNext;
    *piDocid = iDocid;
  }else{
    int iMul = (bDescIdx ? -1 : 1);
    sqlite3_int64 iDelta;
    fts3GetReverseVarint(&p, aDoclist, &iDelta);
    *piDocid -= (iMul * iDelta);

    if( p==aDoclist ){
      *pbEof = 1;
    }else{
      char *pSave = p;
      fts3ReversePoslist(aDoclist, &p);
      *pnList = (pSave - p);
    }
    *ppIter = p;
  }
}

/*
** Attempt to move the phrase iterator to point to the next matching docid. 
** If an error occurs, return an SQLite error code. Otherwise, return 
** SQLITE_OK.
**
** If there is no "next" entry and no error occurs, then *pbEof is set to
** 1 before returning. Otherwise, if no error occurs and the iterator is
** successfully advanced, *pbEof is set to 0.
*/
static int fts3EvalPhraseNext(
  Fts3Cursor *pCsr, 
  Fts3Phrase *p, 
  u8 *pbEof
){
  int rc = SQLITE_OK;
  Fts3Doclist *pDL = &p->doclist;
  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;

  if( p->bIncr ){
    assert( p->nToken==1 );
    assert( pDL->pNextDocid==0 );
    rc = sqlite3Fts3MsrIncrNext(pTab, p->aToken[0].pSegcsr, 
        &pDL->iDocid, &pDL->pList, &pDL->nList
    );
    if( rc==SQLITE_OK && !pDL->pList ){
      *pbEof = 1;
    }
  }else if( pCsr->bDesc!=pTab->bDescIdx && pDL->nAll ){
    sqlite3Fts3DoclistPrev(pTab->bDescIdx, pDL->aAll, pDL->nAll, 
        &pDL->pNextDocid, &pDL->iDocid, &pDL->nList, pbEof
    );
    pDL->pList = pDL->pNextDocid;
  }else{
    char *pIter;                            /* Used to iterate through aAll */
    char *pEnd = &pDL->aAll[pDL->nAll];     /* 1 byte past end of aAll */
    if( pDL->pNextDocid ){
      pIter = pDL->pNextDocid;
    }else{
      pIter = pDL->aAll;
    }

    if( pIter>=pEnd ){
      /* We have already reached the end of this doclist. EOF. */
      *pbEof = 1;
    }else{
      sqlite3_int64 iDelta;
      pIter += sqlite3Fts3GetVarint(pIter, &iDelta);
      if( pTab->bDescIdx==0 || pDL->pNextDocid==0 ){
        pDL->iDocid += iDelta;
      }else{
        pDL->iDocid -= iDelta;
      }
      pDL->pList = pIter;
      fts3PoslistCopy(0, &pIter);
      pDL->nList = (pIter - pDL->pList);

      /* pIter now points just past the 0x00 that terminates the position-
      ** list for document pDL->iDocid. However, if this position-list was
      ** edited in place by fts3EvalNearTrim2(), then pIter may not actually
      ** point to the start of the next docid value. The following line deals
      ** with this case by advancing pIter past the zero-padding added by
      ** fts3EvalNearTrim2().  */
      while( pIter<pEnd && *pIter==0 ) pIter++;

      pDL->pNextDocid = pIter;
      assert( pIter>=&pDL->aAll[pDL->nAll] || *pIter );
      *pbEof = 0;
    }
  }

  return rc;
}

static void fts3EvalStartReaders(
  Fts3Cursor *pCsr, 
  Fts3Expr *pExpr, 
  int bOptOk,
  int *pRc
){
  if( pExpr && SQLITE_OK==*pRc ){
    if( pExpr->eType==FTSQUERY_PHRASE ){
      int i;
      int nToken = pExpr->pPhrase->nToken;
      for(i=0; i<nToken; i++){
        if( pExpr->pPhrase->aToken[i].pDeferred==0 ) break;
      }
      pExpr->bDeferred = (i==nToken);
      *pRc = fts3EvalPhraseStart(pCsr, bOptOk, pExpr->pPhrase);
    }else{
      fts3EvalStartReaders(pCsr, pExpr->pLeft, bOptOk, pRc);
      fts3EvalStartReaders(pCsr, pExpr->pRight, bOptOk, pRc);
      pExpr->bDeferred = (pExpr->pLeft->bDeferred && pExpr->pRight->bDeferred);
    }
  }
}

typedef struct Fts3TokenAndCost Fts3TokenAndCost;
struct Fts3TokenAndCost {
  Fts3Phrase *pPhrase;            /* The phrase the token belongs to */
  int iToken;                     /* Position of token in phrase */
  Fts3PhraseToken *pToken;        /* The token itself */
  Fts3Expr *pRoot; 
  int nOvfl;
  int iCol;                       /* The column the token must match */
};

static void fts3EvalTokenCosts(
  Fts3Cursor *pCsr, 
  Fts3Expr *pRoot, 
  Fts3Expr *pExpr, 
  Fts3TokenAndCost **ppTC,
  Fts3Expr ***ppOr,
  int *pRc
){
  if( *pRc==SQLITE_OK && pExpr ){
    if( pExpr->eType==FTSQUERY_PHRASE ){
      Fts3Phrase *pPhrase = pExpr->pPhrase;
      int i;
      for(i=0; *pRc==SQLITE_OK && i<pPhrase->nToken; i++){
        Fts3TokenAndCost *pTC = (*ppTC)++;
        pTC->pPhrase = pPhrase;
        pTC->iToken = i;
        pTC->pRoot = pRoot;
        pTC->pToken = &pPhrase->aToken[i];
        pTC->iCol = pPhrase->iColumn;
        *pRc = sqlite3Fts3MsrOvfl(pCsr, pTC->pToken->pSegcsr, &pTC->nOvfl);
      }
    }else if( pExpr->eType!=FTSQUERY_NOT ){
      if( pExpr->eType==FTSQUERY_OR ){
        pRoot = pExpr->pLeft;
        **ppOr = pRoot;
        (*ppOr)++;
      }
      fts3EvalTokenCosts(pCsr, pRoot, pExpr->pLeft, ppTC, ppOr, pRc);
      if( pExpr->eType==FTSQUERY_OR ){
        pRoot = pExpr->pRight;
        **ppOr = pRoot;
        (*ppOr)++;
      }
      fts3EvalTokenCosts(pCsr, pRoot, pExpr->pRight, ppTC, ppOr, pRc);
    }
  }
}

static int fts3EvalAverageDocsize(Fts3Cursor *pCsr, int *pnPage){
  if( pCsr->nRowAvg==0 ){
    /* The average document size, which is required to calculate the cost
     ** of each doclist, has not yet been determined. Read the required 
     ** data from the %_stat table to calculate it.
     **
     ** Entry 0 of the %_stat table is a blob containing (nCol+1) FTS3 
     ** varints, where nCol is the number of columns in the FTS3 table.
     ** The first varint is the number of documents currently stored in
     ** the table. The following nCol varints contain the total amount of
     ** data stored in all rows of each column of the table, from left
     ** to right.
     */
    int rc;
    Fts3Table *p = (Fts3Table*)pCsr->base.pVtab;
    sqlite3_stmt *pStmt;
    sqlite3_int64 nDoc = 0;
    sqlite3_int64 nByte = 0;
    const char *pEnd;
    const char *a;

    rc = sqlite3Fts3SelectDoctotal(p, &pStmt);
    if( rc!=SQLITE_OK ) return rc;
    a = sqlite3_column_blob(pStmt, 0);
    assert( a );

    pEnd = &a[sqlite3_column_bytes(pStmt, 0)];
    a += sqlite3Fts3GetVarint(a, &nDoc);
    while( a<pEnd ){
      a += sqlite3Fts3GetVarint(a, &nByte);
    }
    if( nDoc==0 || nByte==0 ){
      sqlite3_reset(pStmt);
      return SQLITE_CORRUPT_VTAB;
    }

    pCsr->nDoc = nDoc;
    pCsr->nRowAvg = (int)(((nByte / nDoc) + p->nPgsz) / p->nPgsz);
    assert( pCsr->nRowAvg>0 ); 
    rc = sqlite3_reset(pStmt);
    if( rc!=SQLITE_OK ) return rc;
  }

  *pnPage = pCsr->nRowAvg;
  return SQLITE_OK;
}

static int fts3EvalSelectDeferred(
  Fts3Cursor *pCsr,
  Fts3Expr *pRoot,
  Fts3TokenAndCost *aTC,
  int nTC
){
  int nDocSize = 0;
  int nDocEst = 0;
  int rc = SQLITE_OK;
  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
  int ii;

  int nOvfl = 0;
  int nTerm = 0;

  for(ii=0; ii<nTC; ii++){
    if( aTC[ii].pRoot==pRoot ){
      nOvfl += aTC[ii].nOvfl;
      nTerm++;
    }
  }
  if( nOvfl==0 || nTerm<2 ) return SQLITE_OK;

  rc = fts3EvalAverageDocsize(pCsr, &nDocSize);

  for(ii=0; ii<nTerm && rc==SQLITE_OK; ii++){
    int jj;
    Fts3TokenAndCost *pTC = 0;

    for(jj=0; jj<nTC; jj++){
      if( aTC[jj].pToken && aTC[jj].pRoot==pRoot 
       && (!pTC || aTC[jj].nOvfl<pTC->nOvfl) 
      ){
        pTC = &aTC[jj];
      }
    }
    assert( pTC );

    /* At this point pTC points to the cheapest remaining token. */
    if( ii==0 ){
      if( pTC->nOvfl ){
        nDocEst = (pTC->nOvfl * pTab->nPgsz + pTab->nPgsz) / 10;
      }else{
        Fts3PhraseToken *pToken = pTC->pToken;
        int nList = 0;
        char *pList = 0;
        rc = fts3TermSelect(pTab, pToken, pTC->iCol, 1, &nList, &pList);
        assert( rc==SQLITE_OK || pList==0 );

        if( rc==SQLITE_OK ){
          nDocEst = fts3DoclistCountDocids(1, pList, nList);
          fts3EvalPhraseMergeToken(pTab, pTC->pPhrase, pTC->iToken,pList,nList);
        }
      }
    }else{
      if( pTC->nOvfl>=(nDocEst*nDocSize) ){
        Fts3PhraseToken *pToken = pTC->pToken;
        rc = sqlite3Fts3DeferToken(pCsr, pToken, pTC->iCol);
        fts3SegReaderCursorFree(pToken->pSegcsr);
        pToken->pSegcsr = 0;
      }
      nDocEst = 1 + (nDocEst/4);
    }
    pTC->pToken = 0;
  }

  return rc;
}

SQLITE_PRIVATE int sqlite3Fts3EvalStart(Fts3Cursor *pCsr, Fts3Expr *pExpr, int bOptOk){
  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
  int rc = SQLITE_OK;
  int nToken = 0;
  int nOr = 0;

  /* Allocate a MultiSegReader for each token in the expression. */
  fts3EvalAllocateReaders(pCsr, pExpr, &nToken, &nOr, &rc);

  /* Call fts3EvalPhraseStart() on all phrases in the expression. TODO:
  ** This call will eventually also be responsible for determining which
  ** tokens are 'deferred' until the document text is loaded into memory.
  **
  ** Each token in each phrase is dealt with using one of the following
  ** three strategies:
  **
  **   1. Entire doclist loaded into memory as part of the
  **      fts3EvalStartReaders() call.
  **
  **   2. Doclist loaded into memory incrementally, as part of each
  **      sqlite3Fts3EvalNext() call.
  **
  **   3. Token doclist is never loaded. Instead, documents are loaded into
  **      memory and scanned for the token as part of the sqlite3Fts3EvalNext()
  **      call. This is known as a "deferred" token.
  */

  /* If bOptOk is true, check if there are any tokens that should be deferred.
  */
  if( rc==SQLITE_OK && bOptOk && nToken>1 && pTab->bHasStat ){
    Fts3TokenAndCost *aTC;
    Fts3Expr **apOr;
    aTC = (Fts3TokenAndCost *)sqlite3_malloc(
        sizeof(Fts3TokenAndCost) * nToken
      + sizeof(Fts3Expr *) * nOr * 2
    );
    apOr = (Fts3Expr **)&aTC[nToken];

    if( !aTC ){
      rc = SQLITE_NOMEM;
    }else{
      int ii;
      Fts3TokenAndCost *pTC = aTC;
      Fts3Expr **ppOr = apOr;

      fts3EvalTokenCosts(pCsr, 0, pExpr, &pTC, &ppOr, &rc);
      nToken = pTC-aTC;
      nOr = ppOr-apOr;

      if( rc==SQLITE_OK ){
        rc = fts3EvalSelectDeferred(pCsr, 0, aTC, nToken);
        for(ii=0; rc==SQLITE_OK && ii<nOr; ii++){
          rc = fts3EvalSelectDeferred(pCsr, apOr[ii], aTC, nToken);
        }
      }

      sqlite3_free(aTC);
    }
  }

  fts3EvalStartReaders(pCsr, pExpr, bOptOk, &rc);
  return rc;
}

static void fts3EvalZeroPoslist(Fts3Phrase *pPhrase){
  if( pPhrase->doclist.bFreeList ){
    sqlite3_free(pPhrase->doclist.pList);
  }
  pPhrase->doclist.pList = 0;
  pPhrase->doclist.nList = 0;
  pPhrase->doclist.bFreeList = 0;
}

static int fts3EvalNearTrim2(
  int nNear,
  char *aTmp,                     /* Temporary space to use */
  char **paPoslist,               /* IN/OUT: Position list */
  int *pnToken,                   /* IN/OUT: Tokens in phrase of *paPoslist */
  Fts3Phrase *pPhrase             /* The phrase object to trim the doclist of */
){
  int nParam1 = nNear + pPhrase->nToken;
  int nParam2 = nNear + *pnToken;
  int nNew;
  char *p2; 
  char *pOut; 
  int res;

  assert( pPhrase->doclist.pList );

  p2 = pOut = pPhrase->doclist.pList;
  res = fts3PoslistNearMerge(
    &pOut, aTmp, nParam1, nParam2, paPoslist, &p2
  );
  if( res ){
    nNew = (pOut - pPhrase->doclist.pList) - 1;
    assert( pPhrase->doclist.pList[nNew]=='\0' );
    assert( nNew<=pPhrase->doclist.nList && nNew>0 );
    memset(&pPhrase->doclist.pList[nNew], 0, pPhrase->doclist.nList - nNew);
    pPhrase->doclist.nList = nNew;
    *paPoslist = pPhrase->doclist.pList;
    *pnToken = pPhrase->nToken;
  }

  return res;
}

static int fts3EvalNearTest(Fts3Expr *pExpr, int *pRc){
  int res = 1;

  /* The following block runs if pExpr is the root of a NEAR query.
  ** For example, the query:
  **
  **         "w" NEAR "x" NEAR "y" NEAR "z"
  **
  ** which is represented in tree form as:
  **
  **                               |
  **                          +--NEAR--+      <-- root of NEAR query
  **                          |        |
  **                     +--NEAR--+   "z"
  **                     |        |
  **                +--NEAR--+   "y"
  **                |        |
  **               "w"      "x"
  **
  ** The right-hand child of a NEAR node is always a phrase. The 
  ** left-hand child may be either a phrase or a NEAR node. There are
  ** no exceptions to this.
  */
  if( *pRc==SQLITE_OK 
   && pExpr->eType==FTSQUERY_NEAR 
   && pExpr->bEof==0
   && (pExpr->pParent==0 || pExpr->pParent->eType!=FTSQUERY_NEAR)
  ){
    Fts3Expr *p; 
    int nTmp = 0;                 /* Bytes of temp space */
    char *aTmp;                   /* Temp space for PoslistNearMerge() */

    /* Allocate temporary working space. */
    for(p=pExpr; p->pLeft; p=p->pLeft){
      nTmp += p->pRight->pPhrase->doclist.nList;
    }
    nTmp += p->pPhrase->doclist.nList;
    aTmp = sqlite3_malloc(nTmp*2);
    if( !aTmp ){
      *pRc = SQLITE_NOMEM;
      res = 0;
    }else{
      char *aPoslist = p->pPhrase->doclist.pList;
      int nToken = p->pPhrase->nToken;

      for(p=p->pParent;res && p && p->eType==FTSQUERY_NEAR; p=p->pParent){
        Fts3Phrase *pPhrase = p->pRight->pPhrase;
        int nNear = p->nNear;
        res = fts3EvalNearTrim2(nNear, aTmp, &aPoslist, &nToken, pPhrase);
      }
  
      aPoslist = pExpr->pRight->pPhrase->doclist.pList;
      nToken = pExpr->pRight->pPhrase->nToken;
      for(p=pExpr->pLeft; p && res; p=p->pLeft){
        int nNear = p->pParent->nNear;
        Fts3Phrase *pPhrase = (
            p->eType==FTSQUERY_NEAR ? p->pRight->pPhrase : p->pPhrase
        );
        res = fts3EvalNearTrim2(nNear, aTmp, &aPoslist, &nToken, pPhrase);
      }
    }

    sqlite3_free(aTmp);
  }

  return res;
}

/*
** This macro is used by the fts3EvalNext() function. The two arguments are
** 64-bit docid values. If the current query is "ORDER BY docid ASC", then
** the macro returns (i1 - i2). Or if it is "ORDER BY docid DESC", then
** it returns (i2 - i1). This allows the same code to be used for merging
** doclists in ascending or descending order.
*/
#define DOCID_CMP(i1, i2) ((pCsr->bDesc?-1:1) * (i1-i2))

static void fts3EvalNext(
  Fts3Cursor *pCsr, 
  Fts3Expr *pExpr, 
  int *pRc
){
  if( *pRc==SQLITE_OK ){
    assert( pExpr->bEof==0 );
    pExpr->bStart = 1;

    switch( pExpr->eType ){
      case FTSQUERY_NEAR:
      case FTSQUERY_AND: {
        Fts3Expr *pLeft = pExpr->pLeft;
        Fts3Expr *pRight = pExpr->pRight;
        assert( !pLeft->bDeferred || !pRight->bDeferred );
        if( pLeft->bDeferred ){
          fts3EvalNext(pCsr, pRight, pRc);
          pExpr->iDocid = pRight->iDocid;
          pExpr->bEof = pRight->bEof;
        }else if( pRight->bDeferred ){
          fts3EvalNext(pCsr, pLeft, pRc);
          pExpr->iDocid = pLeft->iDocid;
          pExpr->bEof = pLeft->bEof;
        }else{
          fts3EvalNext(pCsr, pLeft, pRc);
          fts3EvalNext(pCsr, pRight, pRc);

          while( !pLeft->bEof && !pRight->bEof && *pRc==SQLITE_OK ){
            sqlite3_int64 iDiff = DOCID_CMP(pLeft->iDocid, pRight->iDocid);
            if( iDiff==0 ) break;
            if( iDiff<0 ){
              fts3EvalNext(pCsr, pLeft, pRc);
            }else{
              fts3EvalNext(pCsr, pRight, pRc);
            }
          }

          pExpr->iDocid = pLeft->iDocid;
          pExpr->bEof = (pLeft->bEof || pRight->bEof);
        }
        break;
      }
  
      case FTSQUERY_OR: {
        Fts3Expr *pLeft = pExpr->pLeft;
        Fts3Expr *pRight = pExpr->pRight;
        sqlite3_int64 iCmp = DOCID_CMP(pLeft->iDocid, pRight->iDocid);

        assert( pLeft->bStart || pLeft->iDocid==pRight->iDocid );
        assert( pRight->bStart || pLeft->iDocid==pRight->iDocid );

        if( pRight->bEof || (pLeft->bEof==0 && iCmp<0) ){
          fts3EvalNext(pCsr, pLeft, pRc);
        }else if( pLeft->bEof || (pRight->bEof==0 && iCmp>0) ){
          fts3EvalNext(pCsr, pRight, pRc);
        }else{
          fts3EvalNext(pCsr, pLeft, pRc);
          fts3EvalNext(pCsr, pRight, pRc);
        }

        pExpr->bEof = (pLeft->bEof && pRight->bEof);
        iCmp = DOCID_CMP(pLeft->iDocid, pRight->iDocid);
        if( pRight->bEof || (pLeft->bEof==0 &&  iCmp<0) ){
          pExpr->iDocid = pLeft->iDocid;
        }else{
          pExpr->iDocid = pRight->iDocid;
        }

        break;
      }

      case FTSQUERY_NOT: {
        Fts3Expr *pLeft = pExpr->pLeft;
        Fts3Expr *pRight = pExpr->pRight;

        if( pRight->bStart==0 ){
          fts3EvalNext(pCsr, pRight, pRc);
          assert( *pRc!=SQLITE_OK || pRight->bStart );
        }

        fts3EvalNext(pCsr, pLeft, pRc);
        if( pLeft->bEof==0 ){
          while( !*pRc 
              && !pRight->bEof 
              && DOCID_CMP(pLeft->iDocid, pRight->iDocid)>0 
          ){
            fts3EvalNext(pCsr, pRight, pRc);
          }
        }
        pExpr->iDocid = pLeft->iDocid;
        pExpr->bEof = pLeft->bEof;
        break;
      }

      default: {
        Fts3Phrase *pPhrase = pExpr->pPhrase;
        fts3EvalZeroPoslist(pPhrase);
        *pRc = fts3EvalPhraseNext(pCsr, pPhrase, &pExpr->bEof);
        pExpr->iDocid = pPhrase->doclist.iDocid;
        break;
      }
    }
  }
}

static int fts3EvalDeferredTest(Fts3Cursor *pCsr, Fts3Expr *pExpr, int *pRc){
  int bHit = 1;
  if( *pRc==SQLITE_OK ){
    switch( pExpr->eType ){
      case FTSQUERY_NEAR:
      case FTSQUERY_AND:
        bHit = (
            fts3EvalDeferredTest(pCsr, pExpr->pLeft, pRc)
         && fts3EvalDeferredTest(pCsr, pExpr->pRight, pRc)
         && fts3EvalNearTest(pExpr, pRc)
        );

        /* If the NEAR expression does not match any rows, zero the doclist for 
        ** all phrases involved in the NEAR. This is because the snippet(),
        ** offsets() and matchinfo() functions are not supposed to recognize 
        ** any instances of phrases that are part of unmatched NEAR queries. 
        ** For example if this expression:
        **
        **    ... MATCH 'a OR (b NEAR c)'
        **
        ** is matched against a row containing:
        **
        **        'a b d e'
        **
        ** then any snippet() should ony highlight the "a" term, not the "b"
        ** (as "b" is part of a non-matching NEAR clause).
        */
        if( bHit==0 
         && pExpr->eType==FTSQUERY_NEAR 
         && (pExpr->pParent==0 || pExpr->pParent->eType!=FTSQUERY_NEAR)
        ){
          Fts3Expr *p;
          for(p=pExpr; p->pPhrase==0; p=p->pLeft){
            if( p->pRight->iDocid==pCsr->iPrevId ){
              fts3EvalZeroPoslist(p->pRight->pPhrase);
            }
          }
          if( p->iDocid==pCsr->iPrevId ){
            fts3EvalZeroPoslist(p->pPhrase);
          }
        }

        break;

      case FTSQUERY_OR: {
        int bHit1 = fts3EvalDeferredTest(pCsr, pExpr->pLeft, pRc);
        int bHit2 = fts3EvalDeferredTest(pCsr, pExpr->pRight, pRc);
        bHit = bHit1 || bHit2;
        break;
      }

      case FTSQUERY_NOT:
        bHit = (
            fts3EvalDeferredTest(pCsr, pExpr->pLeft, pRc)
         && !fts3EvalDeferredTest(pCsr, pExpr->pRight, pRc)
        );
        break;

      default: {
        if( pCsr->pDeferred 
         && (pExpr->iDocid==pCsr->iPrevId || pExpr->bDeferred)
        ){
          Fts3Phrase *pPhrase = pExpr->pPhrase;
          assert( pExpr->bDeferred || pPhrase->doclist.bFreeList==0 );
          if( pExpr->bDeferred ){
            fts3EvalZeroPoslist(pPhrase);
          }
          *pRc = fts3EvalDeferredPhrase(pCsr, pPhrase);
          bHit = (pPhrase->doclist.pList!=0);
          pExpr->iDocid = pCsr->iPrevId;
        }else{
          bHit = (pExpr->bEof==0 && pExpr->iDocid==pCsr->iPrevId);
        }
        break;
      }
    }
  }
  return bHit;
}

/*
** Return 1 if both of the following are true:
**
**   1. *pRc is SQLITE_OK when this function returns, and
**
**   2. After scanning the current FTS table row for the deferred tokens,
**      it is determined that the row does not match the query.
**
** Or, if no error occurs and it seems the current row does match the FTS
** query, return 0.
*/
static int fts3EvalLoadDeferred(Fts3Cursor *pCsr, int *pRc){
  int rc = *pRc;
  int bMiss = 0;
  if( rc==SQLITE_OK ){
    if( pCsr->pDeferred ){
      rc = fts3CursorSeek(0, pCsr);
      if( rc==SQLITE_OK ){
        rc = sqlite3Fts3CacheDeferredDoclists(pCsr);
      }
    }
    bMiss = (0==fts3EvalDeferredTest(pCsr, pCsr->pExpr, &rc));
    sqlite3Fts3FreeDeferredDoclists(pCsr);
    *pRc = rc;
  }
  return (rc==SQLITE_OK && bMiss);
}

/*
** Advance to the next document that matches the FTS expression in
** Fts3Cursor.pExpr.
*/
SQLITE_PRIVATE int sqlite3Fts3EvalNext(Fts3Cursor *pCsr){
  int rc = SQLITE_OK;             /* Return Code */
  Fts3Expr *pExpr = pCsr->pExpr;
  assert( pCsr->isEof==0 );
  if( pExpr==0 ){
    pCsr->isEof = 1;
  }else{
    do {
      if( pCsr->isRequireSeek==0 ){
        sqlite3_reset(pCsr->pStmt);
      }
      assert( sqlite3_data_count(pCsr->pStmt)==0 );
      fts3EvalNext(pCsr, pExpr, &rc);
      pCsr->isEof = pExpr->bEof;
      pCsr->isRequireSeek = 1;
      pCsr->isMatchinfoNeeded = 1;
      pCsr->iPrevId = pExpr->iDocid;
    }while( pCsr->isEof==0 && fts3EvalLoadDeferred(pCsr, &rc) );
  }
  return rc;
}

/*
** Restart interation for expression pExpr so that the next call to
** sqlite3Fts3EvalNext() visits the first row. Do not allow incremental 
** loading or merging of phrase doclists for this iteration.
**
** If *pRc is other than SQLITE_OK when this function is called, it is
** a no-op. If an error occurs within this function, *pRc is set to an
** SQLite error code before returning.
*/
static void fts3EvalRestart(
  Fts3Cursor *pCsr,
  Fts3Expr *pExpr,
  int *pRc
){
  if( pExpr && *pRc==SQLITE_OK ){
    Fts3Phrase *pPhrase = pExpr->pPhrase;

    if( pPhrase ){
      fts3EvalZeroPoslist(pPhrase);
      if( pPhrase->bIncr ){
        assert( pPhrase->nToken==1 );
        assert( pPhrase->aToken[0].pSegcsr );
        sqlite3Fts3MsrIncrRestart(pPhrase->aToken[0].pSegcsr);
        *pRc = fts3EvalPhraseStart(pCsr, 0, pPhrase);
      }

      pPhrase->doclist.pNextDocid = 0;
      pPhrase->doclist.iDocid = 0;
    }

    pExpr->iDocid = 0;
    pExpr->bEof = 0;
    pExpr->bStart = 0;

    fts3EvalRestart(pCsr, pExpr->pLeft, pRc);
    fts3EvalRestart(pCsr, pExpr->pRight, pRc);
  }
}

/*
** After allocating the Fts3Expr.aMI[] array for each phrase in the 
** expression rooted at pExpr, the cursor iterates through all rows matched
** by pExpr, calling this function for each row. This function increments
** the values in Fts3Expr.aMI[] according to the position-list currently
** found in Fts3Expr.pPhrase->doclist.pList for each of the phrase 
** expression nodes.
*/
static void fts3EvalUpdateCounts(Fts3Expr *pExpr){
  if( pExpr ){
    Fts3Phrase *pPhrase = pExpr->pPhrase;
    if( pPhrase && pPhrase->doclist.pList ){
      int iCol = 0;
      char *p = pPhrase->doclist.pList;

      assert( *p );
      while( 1 ){
        u8 c = 0;
        int iCnt = 0;
        while( 0xFE & (*p | c) ){
          if( (c&0x80)==0 ) iCnt++;
          c = *p++ & 0x80;
        }

        /* aMI[iCol*3 + 1] = Number of occurrences
        ** aMI[iCol*3 + 2] = Number of rows containing at least one instance
        */
        pExpr->aMI[iCol*3 + 1] += iCnt;
        pExpr->aMI[iCol*3 + 2] += (iCnt>0);
        if( *p==0x00 ) break;
        p++;
        p += sqlite3Fts3GetVarint32(p, &iCol);
      }
    }

    fts3EvalUpdateCounts(pExpr->pLeft);
    fts3EvalUpdateCounts(pExpr->pRight);
  }
}

/*
** Expression pExpr must be of type FTSQUERY_PHRASE.
**
** If it is not already allocated and populated, this function allocates and
** populates the Fts3Expr.aMI[] array for expression pExpr. If pExpr is part
** of a NEAR expression, then it also allocates and populates the same array
** for all other phrases that are part of the NEAR expression.
**
** SQLITE_OK is returned if the aMI[] array is successfully allocated and
** populated. Otherwise, if an error occurs, an SQLite error code is returned.
*/
static int fts3EvalGatherStats(
  Fts3Cursor *pCsr,               /* Cursor object */
  Fts3Expr *pExpr                 /* FTSQUERY_PHRASE expression */
){
  int rc = SQLITE_OK;             /* Return code */

  assert( pExpr->eType==FTSQUERY_PHRASE );
  if( pExpr->aMI==0 ){
    Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
    Fts3Expr *pRoot;                /* Root of NEAR expression */
    Fts3Expr *p;                    /* Iterator used for several purposes */

    sqlite3_int64 iPrevId = pCsr->iPrevId;
    sqlite3_int64 iDocid;
    u8 bEof;

    /* Find the root of the NEAR expression */
    pRoot = pExpr;
    while( pRoot->pParent && pRoot->pParent->eType==FTSQUERY_NEAR ){
      pRoot = pRoot->pParent;
    }
    iDocid = pRoot->iDocid;
    bEof = pRoot->bEof;
    assert( pRoot->bStart );

    /* Allocate space for the aMSI[] array of each FTSQUERY_PHRASE node */
    for(p=pRoot; p; p=p->pLeft){
      Fts3Expr *pE = (p->eType==FTSQUERY_PHRASE?p:p->pRight);
      assert( pE->aMI==0 );
      pE->aMI = (u32 *)sqlite3_malloc(pTab->nColumn * 3 * sizeof(u32));
      if( !pE->aMI ) return SQLITE_NOMEM;
      memset(pE->aMI, 0, pTab->nColumn * 3 * sizeof(u32));
    }

    fts3EvalRestart(pCsr, pRoot, &rc);

    while( pCsr->isEof==0 && rc==SQLITE_OK ){

      do {
        /* Ensure the %_content statement is reset. */
        if( pCsr->isRequireSeek==0 ) sqlite3_reset(pCsr->pStmt);
        assert( sqlite3_data_count(pCsr->pStmt)==0 );

        /* Advance to the next document */
        fts3EvalNext(pCsr, pRoot, &rc);
        pCsr->isEof = pRoot->bEof;
        pCsr->isRequireSeek = 1;
        pCsr->isMatchinfoNeeded = 1;
        pCsr->iPrevId = pRoot->iDocid;
      }while( pCsr->isEof==0 
           && pRoot->eType==FTSQUERY_NEAR 
           && fts3EvalLoadDeferred(pCsr, &rc) 
      );

      if( rc==SQLITE_OK && pCsr->isEof==0 ){
        fts3EvalUpdateCounts(pRoot);
      }
    }

    pCsr->isEof = 0;
    pCsr->iPrevId = iPrevId;

    if( bEof ){
      pRoot->bEof = bEof;
    }else{
      /* Caution: pRoot may iterate through docids in ascending or descending
      ** order. For this reason, even though it seems more defensive, the 
      ** do loop can not be written:
      **
      **   do {...} while( pRoot->iDocid<iDocid && rc==SQLITE_OK );
      */
      fts3EvalRestart(pCsr, pRoot, &rc);
      do {
        fts3EvalNext(pCsr, pRoot, &rc);
        assert( pRoot->bEof==0 );
      }while( pRoot->iDocid!=iDocid && rc==SQLITE_OK );
      fts3EvalLoadDeferred(pCsr, &rc);
    }
  }
  return rc;
}

/*
** This function is used by the matchinfo() module to query a phrase 
** expression node for the following information:
**
**   1. The total number of occurrences of the phrase in each column of 
**      the FTS table (considering all rows), and
**
**   2. For each column, the number of rows in the table for which the
**      column contains at least one instance of the phrase.
**
** If no error occurs, SQLITE_OK is returned and the values for each column
** written into the array aiOut as follows:
**
**   aiOut[iCol*3 + 1] = Number of occurrences
**   aiOut[iCol*3 + 2] = Number of rows containing at least one instance
**
** Caveats:
**
**   * If a phrase consists entirely of deferred tokens, then all output 
**     values are set to the number of documents in the table. In other
**     words we assume that very common tokens occur exactly once in each 
**     column of each row of the table.
**
**   * If a phrase contains some deferred tokens (and some non-deferred 
**     tokens), count the potential occurrence identified by considering
**     the non-deferred tokens instead of actual phrase occurrences.
**
**   * If the phrase is part of a NEAR expression, then only phrase instances
**     that meet the NEAR constraint are included in the counts.
*/
SQLITE_PRIVATE int sqlite3Fts3EvalPhraseStats(
  Fts3Cursor *pCsr,               /* FTS cursor handle */
  Fts3Expr *pExpr,                /* Phrase expression */
  u32 *aiOut                      /* Array to write results into (see above) */
){
  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
  int rc = SQLITE_OK;
  int iCol;

  if( pExpr->bDeferred && pExpr->pParent->eType!=FTSQUERY_NEAR ){
    assert( pCsr->nDoc>0 );
    for(iCol=0; iCol<pTab->nColumn; iCol++){
      aiOut[iCol*3 + 1] = (u32)pCsr->nDoc;
      aiOut[iCol*3 + 2] = (u32)pCsr->nDoc;
    }
  }else{
    rc = fts3EvalGatherStats(pCsr, pExpr);
    if( rc==SQLITE_OK ){
      assert( pExpr->aMI );
      for(iCol=0; iCol<pTab->nColumn; iCol++){
        aiOut[iCol*3 + 1] = pExpr->aMI[iCol*3 + 1];
        aiOut[iCol*3 + 2] = pExpr->aMI[iCol*3 + 2];
      }
    }
  }

  return rc;
}

/*
** The expression pExpr passed as the second argument to this function
** must be of type FTSQUERY_PHRASE. 
**
** The returned value is either NULL or a pointer to a buffer containing
** a position-list indicating the occurrences of the phrase in column iCol
** of the current row. 
**
** More specifically, the returned buffer contains 1 varint for each 
** occurence of the phrase in the column, stored using the normal (delta+2) 
** compression and is terminated by either an 0x01 or 0x00 byte. For example,
** if the requested column contains "a b X c d X X" and the position-list
** for 'X' is requested, the buffer returned may contain:
**
**     0x04 0x05 0x03 0x01   or   0x04 0x05 0x03 0x00
**
** This function works regardless of whether or not the phrase is deferred,
** incremental, or neither.
*/
SQLITE_PRIVATE char *sqlite3Fts3EvalPhrasePoslist(
  Fts3Cursor *pCsr,               /* FTS3 cursor object */
  Fts3Expr *pExpr,                /* Phrase to return doclist for */
  int iCol                        /* Column to return position list for */
){
  Fts3Phrase *pPhrase = pExpr->pPhrase;
  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
  char *pIter = pPhrase->doclist.pList;
  int iThis;

  assert( iCol>=0 && iCol<pTab->nColumn );
  if( !pIter 
   || pExpr->bEof 
   || pExpr->iDocid!=pCsr->iPrevId
   || (pPhrase->iColumn<pTab->nColumn && pPhrase->iColumn!=iCol) 
  ){
    return 0;
  }

  assert( pPhrase->doclist.nList>0 );
  if( *pIter==0x01 ){
    pIter++;
    pIter += sqlite3Fts3GetVarint32(pIter, &iThis);
  }else{
    iThis = 0;
  }
  while( iThis<iCol ){
    fts3ColumnlistCopy(0, &pIter);
    if( *pIter==0x00 ) return 0;
    pIter++;
    pIter += sqlite3Fts3GetVarint32(pIter, &iThis);
  }

  return ((iCol==iThis)?pIter:0);
}

/*
** Free all components of the Fts3Phrase structure that were allocated by
** the eval module. Specifically, this means to free:
**
**   * the contents of pPhrase->doclist, and
**   * any Fts3MultiSegReader objects held by phrase tokens.
*/
SQLITE_PRIVATE void sqlite3Fts3EvalPhraseCleanup(Fts3Phrase *pPhrase){
  if( pPhrase ){
    int i;
    sqlite3_free(pPhrase->doclist.aAll);
    fts3EvalZeroPoslist(pPhrase);
    memset(&pPhrase->doclist, 0, sizeof(Fts3Doclist));
    for(i=0; i<pPhrase->nToken; i++){
      fts3SegReaderCursorFree(pPhrase->aToken[i].pSegcsr);
      pPhrase->aToken[i].pSegcsr = 0;
    }
  }
}

#endif

/************** End of fts3.c ************************************************/
/************** Begin file fts3_aux.c ****************************************/
/*
** 2011 Jan 27
**
................................................................................
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
*/

#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)


typedef struct Fts3auxTable Fts3auxTable;
typedef struct Fts3auxCursor Fts3auxCursor;

struct Fts3auxTable {
  sqlite3_vtab base;              /* Base class used by SQLite core */
  Fts3Table *pFts3Tab;
};

struct Fts3auxCursor {
  sqlite3_vtab_cursor base;       /* Base class used by SQLite core */
  Fts3MultiSegReader csr;        /* Must be right after "base" */
  Fts3SegFilter filter;
  char *zStop;
  int nStop;                      /* Byte-length of string zStop */
  int isEof;                      /* True if cursor is at EOF */
  sqlite3_int64 iRowid;           /* Current rowid */

  int iCol;                       /* Current value of 'col' column */
................................................................................
  if( !p ) return SQLITE_NOMEM;
  memset(p, 0, nByte);

  p->pFts3Tab = (Fts3Table *)&p[1];
  p->pFts3Tab->zDb = (char *)&p->pFts3Tab[1];
  p->pFts3Tab->zName = &p->pFts3Tab->zDb[nDb+1];
  p->pFts3Tab->db = db;
  p->pFts3Tab->nIndex = 1;

  memcpy((char *)p->pFts3Tab->zDb, zDb, nDb);
  memcpy((char *)p->pFts3Tab->zName, zFts3, nFts3);
  sqlite3Fts3Dequote((char *)p->pFts3Tab->zName);

  *ppVtab = (sqlite3_vtab *)p;
  return SQLITE_OK;
................................................................................
  if( idxNum&FTS4AUX_LE_CONSTRAINT ){
    int iIdx = (idxNum&FTS4AUX_GE_CONSTRAINT) ? 1 : 0;
    pCsr->zStop = sqlite3_mprintf("%s", sqlite3_value_text(apVal[iIdx]));
    pCsr->nStop = sqlite3_value_bytes(apVal[iIdx]);
    if( pCsr->zStop==0 ) return SQLITE_NOMEM;
  }

  rc = sqlite3Fts3SegReaderCursor(pFts3, 0, FTS3_SEGCURSOR_ALL,
      pCsr->filter.zTerm, pCsr->filter.nTerm, 0, isScan, &pCsr->csr
  );
  if( rc==SQLITE_OK ){
    rc = sqlite3Fts3SegReaderStart(pFts3, &pCsr->csr, &pCsr->filter);
  }

  if( rc==SQLITE_OK ) rc = fts3auxNextMethod(pCursor);
................................................................................

/*
** Default span for NEAR operators.
*/
#define SQLITE_FTS3_DEFAULT_NEAR_PARAM 10


/*
** isNot:
**   This variable is used by function getNextNode(). When getNextNode() is
**   called, it sets ParseContext.isNot to true if the 'next node' is a 
**   FTSQUERY_PHRASE with a unary "-" attached to it. i.e. "mysql" in the
**   FTS3 query "sqlite -mysql". Otherwise, ParseContext.isNot is set to
**   zero.
*/
typedef struct ParseContext ParseContext;
struct ParseContext {
  sqlite3_tokenizer *pTokenizer;      /* Tokenizer module */
  const char **azCol;                 /* Array of column names for fts3 table */
  int nCol;                           /* Number of entries in azCol[] */
  int iDefaultCol;                    /* Default column to query */
  int isNot;                          /* True if getNextNode() sees a unary - */
  sqlite3_context *pCtx;              /* Write error message here */
  int nNest;                          /* Number of nested brackets */
};

/*
** This function is equivalent to the standard isspace() function. 
**
................................................................................
        memcpy(pRet->pPhrase->aToken[0].z, zToken, nToken);

        if( iEnd<n && z[iEnd]=='*' ){
          pRet->pPhrase->aToken[0].isPrefix = 1;
          iEnd++;
        }
        if( !sqlite3_fts3_enable_parentheses && iStart>0 && z[iStart-1]=='-' ){
          pParse->isNot = 1;
        }
      }
      nConsumed = iEnd;
    }

    pModule->xClose(pCursor);
  }
................................................................................
  sqlite3_tokenizer_module const *pModule = pTokenizer->pModule;
  int rc;
  Fts3Expr *p = 0;
  sqlite3_tokenizer_cursor *pCursor = 0;
  char *zTemp = 0;
  int nTemp = 0;

  const int nSpace = sizeof(Fts3Expr) + sizeof(Fts3Phrase);
  int nToken = 0;

  /* The final Fts3Expr data structure, including the Fts3Phrase,
  ** Fts3PhraseToken structures token buffers are all stored as a single 
  ** allocation so that the expression can be freed with a single call to
  ** sqlite3_free(). Setting this up requires a two pass approach.
  **
  ** The first pass, in the block below, uses a tokenizer cursor to iterate
  ** through the tokens in the expression. This pass uses fts3ReallocOrFree()
  ** to assemble data in two dynamic buffers:
  **
  **   Buffer p: Points to the Fts3Expr structure, followed by the Fts3Phrase
  **             structure, followed by the array of Fts3PhraseToken 
  **             structures. This pass only populates the Fts3PhraseToken array.
  **
  **   Buffer zTemp: Contains copies of all tokens.
  **
  ** The second pass, in the block that begins "if( rc==SQLITE_DONE )" below,
  ** appends buffer zTemp to buffer p, and fills in the Fts3Expr and Fts3Phrase
  ** structures.
  */
  rc = pModule->xOpen(pTokenizer, zInput, nInput, &pCursor);
  if( rc==SQLITE_OK ){
    int ii;
    pCursor->pTokenizer = pTokenizer;
    for(ii=0; rc==SQLITE_OK; ii++){
      const char *zByte;
      int nByte, iBegin, iEnd, iPos;
      rc = pModule->xNext(pCursor, &zByte, &nByte, &iBegin, &iEnd, &iPos);
      if( rc==SQLITE_OK ){
        Fts3PhraseToken *pToken;

        p = fts3ReallocOrFree(p, nSpace + ii*sizeof(Fts3PhraseToken));
        if( !p ) goto no_mem;

        zTemp = fts3ReallocOrFree(zTemp, nTemp + nByte);
        if( !zTemp ) goto no_mem;

        assert( nToken==ii );
        pToken = &((Fts3Phrase *)(&p[1]))->aToken[ii];
        memset(pToken, 0, sizeof(Fts3PhraseToken));

        memcpy(&zTemp[nTemp], zByte, nByte);
        nTemp += nByte;

        pToken->n = nByte;
        pToken->isPrefix = (iEnd<nInput && zInput[iEnd]=='*');
        nToken = ii+1;



      }
    }

    pModule->xClose(pCursor);
    pCursor = 0;
  }

  if( rc==SQLITE_DONE ){
    int jj;
    char *zBuf = 0;

    p = fts3ReallocOrFree(p, nSpace + nToken*sizeof(Fts3PhraseToken) + nTemp);
    if( !p ) goto no_mem;
    memset(p, 0, (char *)&(((Fts3Phrase *)&p[1])->aToken[0])-(char *)p);
    p->eType = FTSQUERY_PHRASE;
    p->pPhrase = (Fts3Phrase *)&p[1];
    p->pPhrase->iColumn = pParse->iDefaultCol;
    p->pPhrase->nToken = nToken;

    zBuf = (char *)&p->pPhrase->aToken[nToken];
    memcpy(zBuf, zTemp, nTemp);
    sqlite3_free(zTemp);

    for(jj=0; jj<p->pPhrase->nToken; jj++){
      p->pPhrase->aToken[jj].z = zBuf;
      zBuf += p->pPhrase->aToken[jj].n;
    }




    rc = SQLITE_OK;
  }

  *ppExpr = p;
  return rc;
no_mem:

................................................................................
  int iCol;
  int iColLen;
  int rc;
  Fts3Expr *pRet = 0;

  const char *zInput = z;
  int nInput = n;

  pParse->isNot = 0;

  /* Skip over any whitespace before checking for a keyword, an open or
  ** close bracket, or a quoted string. 
  */
  while( nInput>0 && fts3isspace(*zInput) ){
    nInput--;
    zInput++;
................................................................................
    Fts3Expr *p = 0;
    int nByte = 0;
    rc = getNextNode(pParse, zIn, nIn, &p, &nByte);
    if( rc==SQLITE_OK ){
      int isPhrase;

      if( !sqlite3_fts3_enable_parentheses 
       && p->eType==FTSQUERY_PHRASE && pParse->isNot 
      ){
        /* Create an implicit NOT operator. */
        Fts3Expr *pNot = fts3MallocZero(sizeof(Fts3Expr));
        if( !pNot ){
          sqlite3Fts3ExprFree(p);
          rc = SQLITE_NOMEM;
          goto exprparse_out;
................................................................................
        if( pNotBranch ){
          pNot->pLeft = pNotBranch;
        }
        pNotBranch = pNot;
        p = pPrev;
      }else{
        int eType = p->eType;

        isPhrase = (eType==FTSQUERY_PHRASE || p->pLeft);

        /* The isRequirePhrase variable is set to true if a phrase or
        ** an expression contained in parenthesis is required. If a
        ** binary operator (AND, OR, NOT or NEAR) is encounted when
        ** isRequirePhrase is set, this is a syntax error.
        */
................................................................................
}

/*
** Free a parsed fts3 query expression allocated by sqlite3Fts3ExprParse().
*/
SQLITE_PRIVATE void sqlite3Fts3ExprFree(Fts3Expr *p){
  if( p ){
    assert( p->eType==FTSQUERY_PHRASE || p->pPhrase==0 );
    sqlite3Fts3ExprFree(p->pLeft);
    sqlite3Fts3ExprFree(p->pRight);
    sqlite3Fts3EvalPhraseCleanup(p->pPhrase);
    sqlite3_free(p->aMI);
    sqlite3_free(p);
  }
}

/****************************************************************************
*****************************************************************************
** Everything after this point is just test code.
................................................................................
*/
static char *exprToString(Fts3Expr *pExpr, char *zBuf){
  switch( pExpr->eType ){
    case FTSQUERY_PHRASE: {
      Fts3Phrase *pPhrase = pExpr->pPhrase;
      int i;
      zBuf = sqlite3_mprintf(
          "%zPHRASE %d 0", zBuf, pPhrase->iColumn);
      for(i=0; zBuf && i<pPhrase->nToken; i++){
        zBuf = sqlite3_mprintf("%z %.*s%s", zBuf, 
            pPhrase->aToken[i].n, pPhrase->aToken[i].z,
            (pPhrase->aToken[i].isPrefix?"+":"")
        );
      }
      return zBuf;
................................................................................
**     * The FTS3 module is being built as an extension
**       (in which case SQLITE_CORE is not defined), or
**
**     * The FTS3 module is being built into the core of
**       SQLite (in which case SQLITE_ENABLE_FTS3 is defined).
*/
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)




/*
** Class derived from sqlite3_tokenizer
*/
typedef struct porter_tokenizer {
................................................................................
**
**     * The FTS3 module is being built as an extension
**       (in which case SQLITE_CORE is not defined), or
**
**     * The FTS3 module is being built into the core of
**       SQLite (in which case SQLITE_ENABLE_FTS3 is defined).
*/


#ifndef SQLITE_CORE
  SQLITE_EXTENSION_INIT1
#endif

#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)


/*
** Implementation of the SQL scalar function for accessing the underlying 
** hash table. This function may be called as follows:
**
**   SELECT <function-name>(<key-name>);
................................................................................
  Fts3Hash *pHash,                /* Tokenizer hash table */
  const char *zArg,               /* Tokenizer name */
  sqlite3_tokenizer **ppTok,      /* OUT: Tokenizer (if applicable) */
  char **pzErr                    /* OUT: Set to malloced error message */
){
  int rc;
  char *z = (char *)zArg;
  int n = 0;
  char *zCopy;
  char *zEnd;                     /* Pointer to nul-term of zCopy */
  sqlite3_tokenizer_module *m;

  zCopy = sqlite3_mprintf("%s", zArg);
  if( !zCopy ) return SQLITE_NOMEM;
  zEnd = &zCopy[strlen(zCopy)];
................................................................................
**     * The FTS3 module is being built into the core of
**       SQLite (in which case SQLITE_ENABLE_FTS3 is defined).
*/
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)




typedef struct simple_tokenizer {
  sqlite3_tokenizer base;
  char delim[128];             /* flag ASCII delimiters */
} simple_tokenizer;

typedef struct simple_tokenizer_cursor {
  sqlite3_tokenizer_cursor base;
................................................................................
**
** This means that if we have a pointer into a buffer containing node data,
** it is always safe to read up to two varints from it without risking an
** overread, even if the node data is corrupted.
*/
#define FTS3_NODE_PADDING (FTS3_VARINT_MAX*2)

/*
** Under certain circumstances, b-tree nodes (doclists) can be loaded into
** memory incrementally instead of all at once. This can be a big performance
** win (reduced IO and CPU) if SQLite stops calling the virtual table xNext()
** method before retrieving all query results (as may happen, for example,
** if a query has a LIMIT clause).
**
** Incremental loading is used for b-tree nodes FTS3_NODE_CHUNK_THRESHOLD 
** bytes and larger. Nodes are loaded in chunks of FTS3_NODE_CHUNKSIZE bytes.
** The code is written so that the hard lower-limit for each of these values 
** is 1. Clearly such small values would be inefficient, but can be useful 
** for testing purposes.
**
** If this module is built with SQLITE_TEST defined, these constants may
** be overridden at runtime for testing purposes. File fts3_test.c contains
** a Tcl interface to read and write the values.
*/
#ifdef SQLITE_TEST
int test_fts3_node_chunksize = (4*1024);
int test_fts3_node_chunk_threshold = (4*1024)*4;
# define FTS3_NODE_CHUNKSIZE       test_fts3_node_chunksize
# define FTS3_NODE_CHUNK_THRESHOLD test_fts3_node_chunk_threshold
#else
# define FTS3_NODE_CHUNKSIZE (4*1024) 
# define FTS3_NODE_CHUNK_THRESHOLD (FTS3_NODE_CHUNKSIZE*4)
#endif

typedef struct PendingList PendingList;
typedef struct SegmentNode SegmentNode;
typedef struct SegmentWriter SegmentWriter;

/*
** An instance of the following data structure is used to build doclists
** incrementally. See function fts3PendingListAppend() for details.

*/
struct PendingList {
  int nData;
  char *aData;
  int nSpace;
  sqlite3_int64 iLastDocid;
  sqlite3_int64 iLastCol;
................................................................................
** a contiguous set of segment b-tree leaf nodes. Although the details of
** this structure are only manipulated by code in this file, opaque handles
** of type Fts3SegReader* are also used by code in fts3.c to iterate through
** terms when querying the full-text index. See functions:
**
**   sqlite3Fts3SegReaderNew()
**   sqlite3Fts3SegReaderFree()

**   sqlite3Fts3SegReaderIterate()
**
** Methods used to manipulate Fts3SegReader structures:
**
**   fts3SegReaderNext()
**   fts3SegReaderFirstDocid()
**   fts3SegReaderNextDocid()
................................................................................
  sqlite3_int64 iStartBlock;      /* Rowid of first leaf block to traverse */
  sqlite3_int64 iLeafEndBlock;    /* Rowid of final leaf block to traverse */
  sqlite3_int64 iEndBlock;        /* Rowid of final block in segment (or 0) */
  sqlite3_int64 iCurrentBlock;    /* Current leaf block (or 0) */

  char *aNode;                    /* Pointer to node data (or NULL) */
  int nNode;                      /* Size of buffer at aNode (or 0) */
  int nPopulate;                  /* If >0, bytes of buffer aNode[] loaded */
  sqlite3_blob *pBlob;            /* If not NULL, blob handle to read node */

  Fts3HashElem **ppNextElem;

  /* Variables set by fts3SegReaderNext(). These may be read directly
  ** by the caller. They are valid from the time SegmentReaderNew() returns
  ** until SegmentReaderNext() returns something other than SQLITE_OK
  ** (i.e. SQLITE_DONE).
  */
  int nTerm;                      /* Number of bytes in current term */
  char *zTerm;                    /* Pointer to current term */
  int nTermAlloc;                 /* Allocated size of zTerm buffer */
  char *aDoclist;                 /* Pointer to doclist of current entry */
  int nDoclist;                   /* Size of doclist in current entry */

  /* The following variables are used by fts3SegReaderNextDocid() to iterate 
  ** through the current doclist (aDoclist/nDoclist).
  */
  char *pOffsetList;
  int nOffsetList;                /* For descending pending seg-readers only */
  sqlite3_int64 iDocid;
};

#define fts3SegReaderIsPending(p) ((p)->ppNextElem!=0)
#define fts3SegReaderIsRootOnly(p) ((p)->aNode==(char *)&(p)[1])

/*
................................................................................
** the interior part of the segment b+-tree structures (everything except
** the leaf nodes). These functions and type are only ever used by code
** within the fts3SegWriterXXX() family of functions described above.
**
**   fts3NodeAddTerm()
**   fts3NodeWrite()
**   fts3NodeFree()
**
** When a b+tree is written to the database (either as a result of a merge
** or the pending-terms table being flushed), leaves are written into the 
** database file as soon as they are completely populated. The interior of
** the tree is assembled in memory and written out only once all leaves have
** been populated and stored. This is Ok, as the b+-tree fanout is usually
** very large, meaning that the interior of the tree consumes relatively 
** little memory.
*/
struct SegmentNode {
  SegmentNode *pParent;           /* Parent node (or NULL for root node) */
  SegmentNode *pRight;            /* Pointer to right-sibling */
  SegmentNode *pLeftmost;         /* Pointer to left-most node of this depth */
  int nEntry;                     /* Number of terms written to node so far */
  char *zTerm;                    /* Pointer to previous term buffer */
................................................................................
#define SQL_DELETE_ALL_STAT            6
#define SQL_SELECT_CONTENT_BY_ROWID    7
#define SQL_NEXT_SEGMENT_INDEX         8
#define SQL_INSERT_SEGMENTS            9
#define SQL_NEXT_SEGMENTS_ID          10
#define SQL_INSERT_SEGDIR             11
#define SQL_SELECT_LEVEL              12
#define SQL_SELECT_LEVEL_RANGE        13
#define SQL_SELECT_LEVEL_COUNT        14
#define SQL_SELECT_SEGDIR_MAX_LEVEL   15
#define SQL_DELETE_SEGDIR_LEVEL       16
#define SQL_DELETE_SEGMENTS_RANGE     17
#define SQL_CONTENT_INSERT            18
#define SQL_DELETE_DOCSIZE            19
#define SQL_REPLACE_DOCSIZE           20
#define SQL_SELECT_DOCSIZE            21
#define SQL_SELECT_DOCTOTAL           22
#define SQL_REPLACE_DOCTOTAL          23

#define SQL_SELECT_ALL_PREFIX_LEVEL   24
#define SQL_DELETE_ALL_TERMS_SEGDIR   25

#define SQL_DELETE_SEGDIR_RANGE       26

/*
** This function is used to obtain an SQLite prepared statement handle
** for the statement identified by the second argument. If successful,
** *pp is set to the requested statement handle and SQLITE_OK returned.
** Otherwise, an SQLite error code is returned and *pp is set to 0.
**
................................................................................
/* 10 */  "SELECT coalesce((SELECT max(blockid) FROM %Q.'%q_segments') + 1, 1)",
/* 11 */  "INSERT INTO %Q.'%q_segdir' VALUES(?,?,?,?,?,?)",

          /* Return segments in order from oldest to newest.*/ 
/* 12 */  "SELECT idx, start_block, leaves_end_block, end_block, root "
            "FROM %Q.'%q_segdir' WHERE level = ? ORDER BY idx ASC",
/* 13 */  "SELECT idx, start_block, leaves_end_block, end_block, root "
            "FROM %Q.'%q_segdir' WHERE level BETWEEN ? AND ?"
            "ORDER BY level DESC, idx ASC",

/* 14 */  "SELECT count(*) FROM %Q.'%q_segdir' WHERE level = ?",
/* 15 */  "SELECT max(level) FROM %Q.'%q_segdir' WHERE level BETWEEN ? AND ?",

/* 16 */  "DELETE FROM %Q.'%q_segdir' WHERE level = ?",
/* 17 */  "DELETE FROM %Q.'%q_segments' WHERE blockid BETWEEN ? AND ?",
/* 18 */  "INSERT INTO %Q.'%q_content' VALUES(%s)",
/* 19 */  "DELETE FROM %Q.'%q_docsize' WHERE docid = ?",
/* 20 */  "REPLACE INTO %Q.'%q_docsize' VALUES(?,?)",
/* 21 */  "SELECT size FROM %Q.'%q_docsize' WHERE docid=?",
/* 22 */  "SELECT value FROM %Q.'%q_stat' WHERE id=0",
/* 23 */  "REPLACE INTO %Q.'%q_stat' VALUES(0,?)",
/* 24 */  "",
/* 25 */  "",

/* 26 */ "DELETE FROM %Q.'%q_segdir' WHERE level BETWEEN ? AND ?",

  };
  int rc = SQLITE_OK;
  sqlite3_stmt *pStmt;

  assert( SizeofArray(azSql)==SizeofArray(p->aStmt) );
  assert( eStmt<SizeofArray(azSql) && eStmt>=0 );
  
................................................................................
**
**   0: idx
**   1: start_block
**   2: leaves_end_block
**   3: end_block
**   4: root
*/
SQLITE_PRIVATE int sqlite3Fts3AllSegdirs(
  Fts3Table *p,                   /* FTS3 table */
  int iIndex,                     /* Index for p->aIndex[] */
  int iLevel,                     /* Level to select */
  sqlite3_stmt **ppStmt           /* OUT: Compiled statement */
){
  int rc;
  sqlite3_stmt *pStmt = 0;

  assert( iLevel==FTS3_SEGCURSOR_ALL || iLevel>=0 );
  assert( iLevel<FTS3_SEGDIR_MAXLEVEL );
  assert( iIndex>=0 && iIndex<p->nIndex );

  if( iLevel<0 ){
    /* "SELECT * FROM %_segdir WHERE level BETWEEN ? AND ? ORDER BY ..." */
    rc = fts3SqlStmt(p, SQL_SELECT_LEVEL_RANGE, &pStmt, 0);
    if( rc==SQLITE_OK ){ 
      sqlite3_bind_int(pStmt, 1, iIndex*FTS3_SEGDIR_MAXLEVEL);
      sqlite3_bind_int(pStmt, 2, (iIndex+1)*FTS3_SEGDIR_MAXLEVEL-1);
    }
  }else{
    /* "SELECT * FROM %_segdir WHERE level = ? ORDER BY ..." */
    rc = fts3SqlStmt(p, SQL_SELECT_LEVEL, &pStmt, 0);
    if( rc==SQLITE_OK ){ 
      sqlite3_bind_int(pStmt, 1, iLevel+iIndex*FTS3_SEGDIR_MAXLEVEL);
    }
  }
  *ppStmt = pStmt;
  return rc;
}


/*
................................................................................
  *pRc = rc;
  if( p!=*pp ){
    *pp = p;
    return 1;
  }
  return 0;
}

/*
** Free a PendingList object allocated by fts3PendingListAppend().
*/
static void fts3PendingListDelete(PendingList *pList){
  sqlite3_free(pList);
}

/*
** Add an entry to one of the pending-terms hash tables.
*/
static int fts3PendingTermsAddOne(
  Fts3Table *p,
  int iCol,
  int iPos,
  Fts3Hash *pHash,                /* Pending terms hash table to add entry to */
  const char *zToken,
  int nToken
){
  PendingList *pList;
  int rc = SQLITE_OK;

  pList = (PendingList *)fts3HashFind(pHash, zToken, nToken);
  if( pList ){
    p->nPendingData -= (pList->nData + nToken + sizeof(Fts3HashElem));
  }
  if( fts3PendingListAppend(&pList, p->iPrevDocid, iCol, iPos, &rc) ){
    if( pList==fts3HashInsert(pHash, zToken, nToken, pList) ){
      /* Malloc failed while inserting the new entry. This can only 
      ** happen if there was no previous entry for this token.
      */
      assert( 0==fts3HashFind(pHash, zToken, nToken) );
      sqlite3_free(pList);
      rc = SQLITE_NOMEM;
    }
  }
  if( rc==SQLITE_OK ){
    p->nPendingData += (pList->nData + nToken + sizeof(Fts3HashElem));
  }
  return rc;
}

/*
** Tokenize the nul-terminated string zText and add all tokens to the
** pending-terms hash-table. The docid used is that currently stored in
** p->iPrevDocid, and the column is specified by argument iCol.
**
** If successful, SQLITE_OK is returned. Otherwise, an SQLite error code.
................................................................................
  }
  pCsr->pTokenizer = pTokenizer;

  xNext = pModule->xNext;
  while( SQLITE_OK==rc
      && SQLITE_OK==(rc = xNext(pCsr, &zToken, &nToken, &iStart, &iEnd, &iPos))
  ){
    int i;

    if( iPos>=nWord ) nWord = iPos+1;

    /* Positions cannot be negative; we use -1 as a terminator internally.
    ** Tokens must have a non-zero length.
    */
    if( iPos<0 || !zToken || nToken<=0 ){
      rc = SQLITE_ERROR;
      break;
    }

    /* Add the term to the terms index */
    rc = fts3PendingTermsAddOne(
        p, iCol, iPos, &p->aIndex[0].hPending, zToken, nToken
    );
    
    /* Add the term to each of the prefix indexes that it is not too 
    ** short for. */
    for(i=1; rc==SQLITE_OK && i<p->nIndex; i++){
      struct Fts3Index *pIndex = &p->aIndex[i];
      if( nToken<pIndex->nPrefix ) continue;
      rc = fts3PendingTermsAddOne(
          p, iCol, iPos, &pIndex->hPending, zToken, pIndex->nPrefix
      );



    }
  }

  pModule->xClose(pCsr);
  *pnWord = nWord;
  return (rc==SQLITE_DONE ? SQLITE_OK : rc);
}
................................................................................
    if( rc!=SQLITE_OK ) return rc;
  }
  p->iPrevDocid = iDocid;
  return SQLITE_OK;
}

/*
** Discard the contents of the pending-terms hash tables. 
*/
SQLITE_PRIVATE void sqlite3Fts3PendingTermsClear(Fts3Table *p){
  int i;
  for(i=0; i<p->nIndex; i++){
    Fts3HashElem *pElem;
    Fts3Hash *pHash = &p->aIndex[i].hPending;
    for(pElem=fts3HashFirst(pHash); pElem; pElem=fts3HashNext(pElem)){
      PendingList *pList = (PendingList *)fts3HashData(pElem);
      fts3PendingListDelete(pList);
    }
    fts3HashClear(pHash);
  }
  p->nPendingData = 0;
}

/*
** This function is called by the xUpdate() method as part of an INSERT
** operation. It adds entries for each term in the new record to the
** pendingTerms hash table.
................................................................................
  *pRC = rc;
}

/*
** Forward declaration to account for the circular dependency between
** functions fts3SegmentMerge() and fts3AllocateSegdirIdx().
*/
static int fts3SegmentMerge(Fts3Table *, int, int);

/* 
** This function allocates a new level iLevel index in the segdir table.
** Usually, indexes are allocated within a level sequentially starting
** with 0, so the allocated index is one greater than the value returned
** by:
**
................................................................................
** However, if there are already FTS3_MERGE_COUNT indexes at the requested
** level, they are merged into a single level (iLevel+1) segment and the 
** allocated index is 0.
**
** If successful, *piIdx is set to the allocated index slot and SQLITE_OK
** returned. Otherwise, an SQLite error code is returned.
*/
static int fts3AllocateSegdirIdx(
  Fts3Table *p, 
  int iIndex,                     /* Index for p->aIndex */
  int iLevel, 
  int *piIdx
){
  int rc;                         /* Return Code */
  sqlite3_stmt *pNextIdx;         /* Query for next idx at level iLevel */
  int iNext = 0;                  /* Result of query pNextIdx */

  /* Set variable iNext to the next available segdir index at level iLevel. */
  rc = fts3SqlStmt(p, SQL_NEXT_SEGMENT_INDEX, &pNextIdx, 0);
  if( rc==SQLITE_OK ){
    sqlite3_bind_int(pNextIdx, 1, iIndex*FTS3_SEGDIR_MAXLEVEL + iLevel);
    if( SQLITE_ROW==sqlite3_step(pNextIdx) ){
      iNext = sqlite3_column_int(pNextIdx, 0);
    }
    rc = sqlite3_reset(pNextIdx);
  }

  if( rc==SQLITE_OK ){
    /* If iNext is FTS3_MERGE_COUNT, indicating that level iLevel is already
    ** full, merge all segments in level iLevel into a single iLevel+1
    ** segment and allocate (newly freed) index 0 at level iLevel. Otherwise,
    ** if iNext is less than FTS3_MERGE_COUNT, allocate index iNext.
    */
    if( iNext>=FTS3_MERGE_COUNT ){
      rc = fts3SegmentMerge(p, iIndex, iLevel);
      *piIdx = 0;
    }else{
      *piIdx = iNext;
    }
  }

  return rc;
................................................................................
** method (xFilter etc.) that may directly or indirectly call this function
** must call sqlite3Fts3SegmentsClose() before returning.
*/
SQLITE_PRIVATE int sqlite3Fts3ReadBlock(
  Fts3Table *p,                   /* FTS3 table handle */
  sqlite3_int64 iBlockid,         /* Access the row with blockid=$iBlockid */
  char **paBlob,                  /* OUT: Blob data in malloc'd buffer */
  int *pnBlob,                    /* OUT: Size of blob data */
  int *pnLoad                     /* OUT: Bytes actually loaded */
){
  int rc;                         /* Return code */

  /* pnBlob must be non-NULL. paBlob may be NULL or non-NULL. */
  assert( pnBlob);

  if( p->pSegments ){
................................................................................
    rc = sqlite3_blob_open(
       p->db, p->zDb, p->zSegmentsTbl, "block", iBlockid, 0, &p->pSegments
    );
  }

  if( rc==SQLITE_OK ){
    int nByte = sqlite3_blob_bytes(p->pSegments);
    *pnBlob = nByte;
    if( paBlob ){
      char *aByte = sqlite3_malloc(nByte + FTS3_NODE_PADDING);
      if( !aByte ){
        rc = SQLITE_NOMEM;
      }else{
        if( pnLoad && nByte>(FTS3_NODE_CHUNK_THRESHOLD) ){
          nByte = FTS3_NODE_CHUNKSIZE;
          *pnLoad = nByte;
        }
        rc = sqlite3_blob_read(p->pSegments, aByte, nByte, 0);
        memset(&aByte[nByte], 0, FTS3_NODE_PADDING);
        if( rc!=SQLITE_OK ){
          sqlite3_free(aByte);
          aByte = 0;
        }
      }
      *paBlob = aByte;
    }

  }

  return rc;
}

/*
** Close the blob handle at p->pSegments, if it is open. See comments above
** the sqlite3Fts3ReadBlock() function for details.
*/
SQLITE_PRIVATE void sqlite3Fts3SegmentsClose(Fts3Table *p){
  sqlite3_blob_close(p->pSegments);
  p->pSegments = 0;
}
    
static int fts3SegReaderIncrRead(Fts3SegReader *pReader){
  int nRead;                      /* Number of bytes to read */
  int rc;                         /* Return code */

  nRead = MIN(pReader->nNode - pReader->nPopulate, FTS3_NODE_CHUNKSIZE);
  rc = sqlite3_blob_read(
      pReader->pBlob, 
      &pReader->aNode[pReader->nPopulate],
      nRead,
      pReader->nPopulate
  );

  if( rc==SQLITE_OK ){
    pReader->nPopulate += nRead;
    memset(&pReader->aNode[pReader->nPopulate], 0, FTS3_NODE_PADDING);
    if( pReader->nPopulate==pReader->nNode ){
      sqlite3_blob_close(pReader->pBlob);
      pReader->pBlob = 0;
      pReader->nPopulate = 0;
    }
  }
  return rc;
}

static int fts3SegReaderRequire(Fts3SegReader *pReader, char *pFrom, int nByte){
  int rc = SQLITE_OK;
  assert( !pReader->pBlob 
       || (pFrom>=pReader->aNode && pFrom<&pReader->aNode[pReader->nNode])
  );
  while( pReader->pBlob && rc==SQLITE_OK 
     &&  (pFrom - pReader->aNode + nByte)>pReader->nPopulate
  ){
    rc = fts3SegReaderIncrRead(pReader);
  }
  return rc;
}

/*
** Move the iterator passed as the first argument to the next term in the
** segment. If successful, SQLITE_OK is returned. If there is no next term,
** SQLITE_DONE. Otherwise, an SQLite error code.
*/
static int fts3SegReaderNext(
  Fts3Table *p, 
  Fts3SegReader *pReader,
  int bIncr
){
  int rc;                         /* Return code of various sub-routines */
  char *pNext;                    /* Cursor variable */
  int nPrefix;                    /* Number of bytes in term prefix */
  int nSuffix;                    /* Number of bytes in term suffix */

  if( !pReader->aDoclist ){
    pNext = pReader->aNode;
  }else{
    pNext = &pReader->aDoclist[pReader->nDoclist];
  }

  if( !pNext || pNext>=&pReader->aNode[pReader->nNode] ){


    if( fts3SegReaderIsPending(pReader) ){
      Fts3HashElem *pElem = *(pReader->ppNextElem);
      if( pElem==0 ){
        pReader->aNode = 0;
      }else{
        PendingList *pList = (PendingList *)fts3HashData(pElem);
................................................................................
        assert( pReader->aNode );
      }
      return SQLITE_OK;
    }

    if( !fts3SegReaderIsRootOnly(pReader) ){
      sqlite3_free(pReader->aNode);
      sqlite3_blob_close(pReader->pBlob);
      pReader->pBlob = 0;
    }
    pReader->aNode = 0;

    /* If iCurrentBlock>=iLeafEndBlock, this is an EOF condition. All leaf 
    ** blocks have already been traversed.  */
    assert( pReader->iCurrentBlock<=pReader->iLeafEndBlock );
    if( pReader->iCurrentBlock>=pReader->iLeafEndBlock ){
      return SQLITE_OK;
    }

    rc = sqlite3Fts3ReadBlock(
        p, ++pReader->iCurrentBlock, &pReader->aNode, &pReader->nNode, 
        (bIncr ? &pReader->nPopulate : 0)
    );
    if( rc!=SQLITE_OK ) return rc;
    assert( pReader->pBlob==0 );
    if( bIncr && pReader->nPopulate<pReader->nNode ){
      pReader->pBlob = p->pSegments;
      p->pSegments = 0;
    }
    pNext = pReader->aNode;
  }

  assert( !fts3SegReaderIsPending(pReader) );

  rc = fts3SegReaderRequire(pReader, pNext, FTS3_VARINT_MAX*2);
  if( rc!=SQLITE_OK ) return rc;
  
  /* Because of the FTS3_NODE_PADDING bytes of padding, the following is 
  ** safe (no risk of overread) even if the node data is corrupted. */

  pNext += sqlite3Fts3GetVarint32(pNext, &nPrefix);
  pNext += sqlite3Fts3GetVarint32(pNext, &nSuffix);
  if( nPrefix<0 || nSuffix<=0 
   || &pNext[nSuffix]>&pReader->aNode[pReader->nNode] 
  ){
    return SQLITE_CORRUPT_VTAB;
  }
................................................................................
    char *zNew = sqlite3_realloc(pReader->zTerm, nNew);
    if( !zNew ){
      return SQLITE_NOMEM;
    }
    pReader->zTerm = zNew;
    pReader->nTermAlloc = nNew;
  }

  rc = fts3SegReaderRequire(pReader, pNext, nSuffix+FTS3_VARINT_MAX);
  if( rc!=SQLITE_OK ) return rc;

  memcpy(&pReader->zTerm[nPrefix], pNext, nSuffix);
  pReader->nTerm = nPrefix+nSuffix;
  pNext += nSuffix;
  pNext += sqlite3Fts3GetVarint32(pNext, &pReader->nDoclist);
  pReader->aDoclist = pNext;
  pReader->pOffsetList = 0;

  /* Check that the doclist does not appear to extend past the end of the
  ** b-tree node. And that the final byte of the doclist is 0x00. If either 
  ** of these statements is untrue, then the data structure is corrupt.
  */
  if( &pReader->aDoclist[pReader->nDoclist]>&pReader->aNode[pReader->nNode] 
   || (pReader->nPopulate==0 && pReader->aDoclist[pReader->nDoclist-1])
  ){
    return SQLITE_CORRUPT_VTAB;
  }
  return SQLITE_OK;
}

/*
** Set the SegReader to point to the first docid in the doclist associated
** with the current term.
*/
static int fts3SegReaderFirstDocid(Fts3Table *pTab, Fts3SegReader *pReader){
  int rc = SQLITE_OK;
  assert( pReader->aDoclist );
  assert( !pReader->pOffsetList );
  if( pTab->bDescIdx && fts3SegReaderIsPending(pReader) ){
    u8 bEof = 0;
    pReader->iDocid = 0;
    pReader->nOffsetList = 0;
    sqlite3Fts3DoclistPrev(0,
        pReader->aDoclist, pReader->nDoclist, &pReader->pOffsetList, 
        &pReader->iDocid, &pReader->nOffsetList, &bEof
    );
  }else{
    rc = fts3SegReaderRequire(pReader, pReader->aDoclist, FTS3_VARINT_MAX);
    if( rc==SQLITE_OK ){
      int n = sqlite3Fts3GetVarint(pReader->aDoclist, &pReader->iDocid);
      pReader->pOffsetList = &pReader->aDoclist[n];
    }
  }
  return rc;
}

/*
** Advance the SegReader to point to the next docid in the doclist
** associated with the current term.
** 
** If arguments ppOffsetList and pnOffsetList are not NULL, then 
** *ppOffsetList is set to point to the first column-offset list
** in the doclist entry (i.e. immediately past the docid varint).
** *pnOffsetList is set to the length of the set of column-offset
** lists, not including the nul-terminator byte. For example:
*/
static int fts3SegReaderNextDocid(
  Fts3Table *pTab,
  Fts3SegReader *pReader,         /* Reader to advance to next docid */
  char **ppOffsetList,            /* OUT: Pointer to current position-list */
  int *pnOffsetList               /* OUT: Length of *ppOffsetList in bytes */
){
  int rc = SQLITE_OK;
  char *p = pReader->pOffsetList;
  char c = 0;

  assert( p );

  if( pTab->bDescIdx && fts3SegReaderIsPending(pReader) ){
    /* A pending-terms seg-reader for an FTS4 table that uses order=desc.
    ** Pending-terms doclists are always built up in ascending order, so
    ** we have to iterate through them backwards here. */
    u8 bEof = 0;
    if( ppOffsetList ){
      *ppOffsetList = pReader->pOffsetList;
      *pnOffsetList = pReader->nOffsetList - 1;
    }
    sqlite3Fts3DoclistPrev(0,
        pReader->aDoclist, pReader->nDoclist, &p, &pReader->iDocid,
        &pReader->nOffsetList, &bEof
    );
    if( bEof ){
      pReader->pOffsetList = 0;
    }else{
      pReader->pOffsetList = p;
    }
  }else{
    char *pEnd = &pReader->aDoclist[pReader->nDoclist];

    /* Pointer p currently points at the first byte of an offset list. The
    ** following block advances it to point one byte past the end of
    ** the same offset list. */
    while( 1 ){
  
      /* The following line of code (and the "p++" below the while() loop) is
      ** normally all that is required to move pointer p to the desired 
      ** position. The exception is if this node is being loaded from disk
      ** incrementally and pointer "p" now points to the first byte passed
      ** the populated part of pReader->aNode[].
      */
      while( *p | c ) c = *p++ & 0x80;
      assert( *p==0 );
  
      if( pReader->pBlob==0 || p<&pReader->aNode[pReader->nPopulate] ) break;
      rc = fts3SegReaderIncrRead(pReader);
      if( rc!=SQLITE_OK ) return rc;
    }
    p++;
  
    /* If required, populate the output variables with a pointer to and the
    ** size of the previous offset-list.
    */
    if( ppOffsetList ){
      *ppOffsetList = pReader->pOffsetList;
      *pnOffsetList = (int)(p - pReader->pOffsetList - 1);
    }

    while( p<pEnd && *p==0 ) p++;
  
    /* If there are no more entries in the doclist, set pOffsetList to
    ** NULL. Otherwise, set Fts3SegReader.iDocid to the next docid and
    ** Fts3SegReader.pOffsetList to point to the next offset list before
    ** returning.
    */

    if( p>=pEnd ){
      pReader->pOffsetList = 0;
    }else{
      rc = fts3SegReaderRequire(pReader, p, FTS3_VARINT_MAX);
      if( rc==SQLITE_OK ){
        sqlite3_int64 iDelta;
        pReader->pOffsetList = p + sqlite3Fts3GetVarint(p, &iDelta);
        if( pTab->bDescIdx ){
          pReader->iDocid -= iDelta;
        }else{
          pReader->iDocid += iDelta;
        }
      }
    }










  }

  return SQLITE_OK;
}


SQLITE_PRIVATE int sqlite3Fts3MsrOvfl(
  Fts3Cursor *pCsr, 


  Fts3MultiSegReader *pMsr,
  int *pnOvfl
){
  Fts3Table *p = (Fts3Table*)pCsr->base.pVtab;
  int nOvfl = 0;
  int ii;
  int rc = SQLITE_OK;

  int pgsz = p->nPgsz;





  assert( p->bHasStat );
  assert( pgsz>0 );

  for(ii=0; rc==SQLITE_OK && ii<pMsr->nSegment; ii++){
    Fts3SegReader *pReader = pMsr->apSegment[ii];
    if( !fts3SegReaderIsPending(pReader) 
     && !fts3SegReaderIsRootOnly(pReader) 
    ){

      sqlite3_int64 jj;












































      for(jj=pReader->iStartBlock; jj<=pReader->iLeafEndBlock; jj++){
        int nBlob;
        rc = sqlite3Fts3ReadBlock(p, jj, 0, &nBlob, 0);
        if( rc!=SQLITE_OK ) break;
        if( (nBlob+35)>pgsz ){
          nOvfl += (nBlob + 34)/pgsz;

        }
      }
    }
  }

  *pnOvfl = nOvfl;
  return rc;
}

/*
** Free all allocations associated with the iterator passed as the 
** second argument.
*/
SQLITE_PRIVATE void sqlite3Fts3SegReaderFree(Fts3SegReader *pReader){
  if( pReader && !fts3SegReaderIsPending(pReader) ){
    sqlite3_free(pReader->zTerm);
    if( !fts3SegReaderIsRootOnly(pReader) ){
      sqlite3_free(pReader->aNode);
      sqlite3_blob_close(pReader->pBlob);
    }
  }
  sqlite3_free(pReader);
}

/*
** Allocate a new SegReader object.
................................................................................
  }
  return c;
}

/*
** This function is used to allocate an Fts3SegReader that iterates through
** a subset of the terms stored in the Fts3Table.pendingTerms array.
**
** If the isPrefixIter parameter is zero, then the returned SegReader iterates
** through each term in the pending-terms table. Or, if isPrefixIter is
** non-zero, it iterates through each term and its prefixes. For example, if
** the pending terms hash table contains the terms "sqlite", "mysql" and
** "firebird", then the iterator visits the following 'terms' (in the order
** shown):
**
**   f fi fir fire fireb firebi firebir firebird
**   m my mys mysq mysql
**   s sq sql sqli sqlit sqlite
**
** Whereas if isPrefixIter is zero, the terms visited are:
**
**   firebird mysql sqlite
*/
SQLITE_PRIVATE int sqlite3Fts3SegReaderPending(
  Fts3Table *p,                   /* Virtual table handle */
  int iIndex,                     /* Index for p->aIndex */
  const char *zTerm,              /* Term to search for */
  int nTerm,                      /* Size of buffer zTerm */
  int bPrefix,                    /* True for a prefix iterator */
  Fts3SegReader **ppReader        /* OUT: SegReader for pending-terms */
){
  Fts3SegReader *pReader = 0;     /* Fts3SegReader object to return */
  Fts3HashElem **aElem = 0;       /* Array of term hash entries to scan */
  int nElem = 0;                  /* Size of array at aElem */
  int rc = SQLITE_OK;             /* Return Code */
  Fts3Hash *pHash;

  pHash = &p->aIndex[iIndex].hPending;
  if( bPrefix ){
    int nAlloc = 0;               /* Size of allocated array at aElem */
    Fts3HashElem *pE = 0;         /* Iterator variable */

    for(pE=fts3HashFirst(pHash); pE; pE=fts3HashNext(pE)){
      char *zKey = (char *)fts3HashKey(pE);
      int nKey = fts3HashKeysize(pE);
      if( nTerm==0 || (nKey>=nTerm && 0==memcmp(zKey, zTerm, nTerm)) ){
        if( nElem==nAlloc ){
          Fts3HashElem **aElem2;
          nAlloc += 16;
          aElem2 = (Fts3HashElem **)sqlite3_realloc(
................................................................................
          if( !aElem2 ){
            rc = SQLITE_NOMEM;
            nElem = 0;
            break;
          }
          aElem = aElem2;
        }

        aElem[nElem++] = pE;
      }
    }

    /* If more than one term matches the prefix, sort the Fts3HashElem
    ** objects in term order using qsort(). This uses the same comparison
    ** callback as is used when flushing terms to disk.
    */
    if( nElem>1 ){
      qsort(aElem, nElem, sizeof(Fts3HashElem *), fts3CompareElemByTerm);
    }

  }else{
    /* The query is a simple term lookup that matches at most one term in
    ** the index. All that is required is a straight hash-lookup. */
    Fts3HashElem *pE = fts3HashFindElem(pHash, zTerm, nTerm);
    if( pE ){
      aElem = &pE;
      nElem = 1;
    }
  }

  if( nElem>0 ){
................................................................................
      memset(pReader, 0, nByte);
      pReader->iIdx = 0x7FFFFFFF;
      pReader->ppNextElem = (Fts3HashElem **)&pReader[1];
      memcpy(pReader->ppNextElem, aElem, nElem*sizeof(Fts3HashElem *));
    }
  }

  if( bPrefix ){
    sqlite3_free(aElem);
  }
  *ppReader = pReader;
  return rc;
}

/*
................................................................................
  int rc = (pLhs->pOffsetList==0)-(pRhs->pOffsetList==0);
  if( rc==0 ){
    if( pLhs->iDocid==pRhs->iDocid ){
      rc = pRhs->iIdx - pLhs->iIdx;
    }else{
      rc = (pLhs->iDocid > pRhs->iDocid) ? 1 : -1;
    }
  }
  assert( pLhs->aNode && pRhs->aNode );
  return rc;
}
static int fts3SegReaderDoclistCmpRev(Fts3SegReader *pLhs, Fts3SegReader *pRhs){
  int rc = (pLhs->pOffsetList==0)-(pRhs->pOffsetList==0);
  if( rc==0 ){
    if( pLhs->iDocid==pRhs->iDocid ){
      rc = pRhs->iIdx - pLhs->iIdx;
    }else{
      rc = (pLhs->iDocid < pRhs->iDocid) ? 1 : -1;
    }
  }
  assert( pLhs->aNode && pRhs->aNode );
  return rc;
}

/*
** Compare the term that the Fts3SegReader object passed as the first argument
................................................................................
    }
    rc = sqlite3_reset(pStmt);
  }
  return rc;
}

/*

** Set *pnMax to the largest segment level in the database for the index
** iIndex.
**
** Segment levels are stored in the 'level' column of the %_segdir table.
**
** Return SQLITE_OK if successful, or an SQLite error code if not.
*/
static int fts3SegmentMaxLevel(Fts3Table *p, int iIndex, int *pnMax){
  sqlite3_stmt *pStmt;
  int rc;
  assert( iIndex>=0 && iIndex<p->nIndex );

  /* Set pStmt to the compiled version of:
  **
  **   SELECT max(level) FROM %Q.'%q_segdir' WHERE level BETWEEN ? AND ?
  **
  ** (1024 is actually the value of macro FTS3_SEGDIR_PREFIXLEVEL_STR).
  */
  rc = fts3SqlStmt(p, SQL_SELECT_SEGDIR_MAX_LEVEL, &pStmt, 0);
  if( rc!=SQLITE_OK ) return rc;
  sqlite3_bind_int(pStmt, 1, iIndex*FTS3_SEGDIR_MAXLEVEL);
  sqlite3_bind_int(pStmt, 2, (iIndex+1)*FTS3_SEGDIR_MAXLEVEL - 1);
  if( SQLITE_ROW==sqlite3_step(pStmt) ){

    *pnMax = sqlite3_column_int(pStmt, 0);
  }
  return sqlite3_reset(pStmt);
}

/*
** This function is used after merging multiple segments into a single large
** segment to delete the old, now redundant, segment b-trees. Specifically,
................................................................................
**   2) deletes all %_segdir entries with level iLevel, or all %_segdir
**      entries regardless of level if (iLevel<0).
**
** SQLITE_OK is returned if successful, otherwise an SQLite error code.
*/
static int fts3DeleteSegdir(
  Fts3Table *p,                   /* Virtual table handle */
  int iIndex,                     /* Index for p->aIndex */
  int iLevel,                     /* Level of %_segdir entries to delete */
  Fts3SegReader **apSegment,      /* Array of SegReader objects */
  int nReader                     /* Size of array apSegment */
){
  int rc;                         /* Return Code */
  int i;                          /* Iterator variable */
  sqlite3_stmt *pDelete;          /* SQL statement to delete rows */
................................................................................
      rc = sqlite3_reset(pDelete);
    }
  }
  if( rc!=SQLITE_OK ){
    return rc;
  }

  assert( iLevel>=0 || iLevel==FTS3_SEGCURSOR_ALL );

  if( iLevel==FTS3_SEGCURSOR_ALL ){
    rc = fts3SqlStmt(p, SQL_DELETE_SEGDIR_RANGE, &pDelete, 0);
    if( rc==SQLITE_OK ){
      sqlite3_bind_int(pDelete, 1, iIndex*FTS3_SEGDIR_MAXLEVEL);
      sqlite3_bind_int(pDelete, 2, (iIndex+1) * FTS3_SEGDIR_MAXLEVEL - 1);
    }
  }else{

    rc = fts3SqlStmt(p, SQL_DELETE_SEGDIR_LEVEL, &pDelete, 0);
    if( rc==SQLITE_OK ){
      sqlite3_bind_int(pDelete, 1, iIndex*FTS3_SEGDIR_MAXLEVEL + iLevel);
    }
  }

  if( rc==SQLITE_OK ){
    sqlite3_step(pDelete);
    rc = sqlite3_reset(pDelete);
  }


  return rc;
}

/*
** When this function is called, buffer *ppList (size *pnList bytes) contains 
** a position list that may (or may not) feature multiple columns. This
................................................................................
    p += sqlite3Fts3GetVarint32(p, &iCurrent);
  }

  *ppList = pList;
  *pnList = nList;
}

/*
** Cache data in the Fts3MultiSegReader.aBuffer[] buffer (overwriting any
** existing data). Grow the buffer if required.
**
** If successful, return SQLITE_OK. Otherwise, if an OOM error is encountered
** trying to resize the buffer, return SQLITE_NOMEM.
*/
static int fts3MsrBufferData(
  Fts3MultiSegReader *pMsr,       /* Multi-segment-reader handle */
  char *pList,
  int nList
){
  if( nList>pMsr->nBuffer ){
    char *pNew;
    pMsr->nBuffer = nList*2;
    pNew = (char *)sqlite3_realloc(pMsr->aBuffer, pMsr->nBuffer);
    if( !pNew ) return SQLITE_NOMEM;
    pMsr->aBuffer = pNew;
  }

  memcpy(pMsr->aBuffer, pList, nList);
  return SQLITE_OK;
}

SQLITE_PRIVATE int sqlite3Fts3MsrIncrNext(
  Fts3Table *p,                   /* Virtual table handle */


  Fts3MultiSegReader *pMsr,       /* Multi-segment-reader handle */
  sqlite3_int64 *piDocid,         /* OUT: Docid value */
  char **paPoslist,               /* OUT: Pointer to position list */
  int *pnPoslist                  /* OUT: Size of position list in bytes */
){
  int nMerge = pMsr->nAdvance;
  Fts3SegReader **apSegment = pMsr->apSegment;
  int (*xCmp)(Fts3SegReader *, Fts3SegReader *) = (
    p->bDescIdx ? fts3SegReaderDoclistCmpRev : fts3SegReaderDoclistCmp
  );

  if( nMerge==0 ){
    *paPoslist = 0;
    return SQLITE_OK;
  }

  while( 1 ){
    Fts3SegReader *pSeg;
    pSeg = pMsr->apSegment[0];

    if( pSeg->pOffsetList==0 ){
      *paPoslist = 0;
      break;
    }else{
      int rc;
      char *pList;
      int nList;
      int j;
      sqlite3_int64 iDocid = apSegment[0]->iDocid;



      rc = fts3SegReaderNextDocid(p, apSegment[0], &pList, &nList);
      j = 1;
      while( rc==SQLITE_OK 
        && j<nMerge
        && apSegment[j]->pOffsetList
        && apSegment[j]->iDocid==iDocid
      ){
        rc = fts3SegReaderNextDocid(p, apSegment[j], 0, 0);
        j++;
      }
      if( rc!=SQLITE_OK ) return rc;
      fts3SegReaderSort(pMsr->apSegment, nMerge, j, xCmp);

      if( pMsr->iColFilter>=0 ){
        fts3ColumnFilter(pMsr->iColFilter, &pList, &nList);
      }

      if( nList>0 ){
        if( fts3SegReaderIsPending(apSegment[0]) ){
          rc = fts3MsrBufferData(pMsr, pList, nList+1);
          if( rc!=SQLITE_OK ) return rc;
          *paPoslist = pMsr->aBuffer;
          assert( (pMsr->aBuffer[nList] & 0xFE)==0x00 );
        }else{
          *paPoslist = pList;
        }
        *piDocid = iDocid;
        *pnPoslist = nList;
        break;
      }
    }
  }

  return SQLITE_OK;
}

static int fts3SegReaderStart(
  Fts3Table *p,                   /* Virtual table handle */
  Fts3MultiSegReader *pCsr,       /* Cursor object */
  const char *zTerm,              /* Term searched for (or NULL) */
  int nTerm                       /* Length of zTerm in bytes */
){
  int i;
  int nSeg = pCsr->nSegment;

  /* If the Fts3SegFilter defines a specific term (or term prefix) to search 
  ** for, then advance each segment iterator until it points to a term of
  ** equal or greater value than the specified term. This prevents many
  ** unnecessary merge/sort operations for the case where single segment
  ** b-tree leaf nodes contain more than one term.
  */
  for(i=0; pCsr->bRestart==0 && i<pCsr->nSegment; i++){


    Fts3SegReader *pSeg = pCsr->apSegment[i];
    do {
      int rc = fts3SegReaderNext(p, pSeg, 0);
      if( rc!=SQLITE_OK ) return rc;
    }while( zTerm && fts3SegReaderTermCmp(pSeg, zTerm, nTerm)<0 );
  }
  fts3SegReaderSort(pCsr->apSegment, nSeg, nSeg, fts3SegReaderCmp);

  return SQLITE_OK;
}

SQLITE_PRIVATE int sqlite3Fts3SegReaderStart(
  Fts3Table *p,                   /* Virtual table handle */
  Fts3MultiSegReader *pCsr,       /* Cursor object */
  Fts3SegFilter *pFilter          /* Restrictions on range of iteration */
){
  pCsr->pFilter = pFilter;
  return fts3SegReaderStart(p, pCsr, pFilter->zTerm, pFilter->nTerm);
}

SQLITE_PRIVATE int sqlite3Fts3MsrIncrStart(
  Fts3Table *p,                   /* Virtual table handle */
  Fts3MultiSegReader *pCsr,       /* Cursor object */
  int iCol,                       /* Column to match on. */
  const char *zTerm,              /* Term to iterate through a doclist for */
  int nTerm                       /* Number of bytes in zTerm */
){
  int i;
  int rc;
  int nSegment = pCsr->nSegment;
  int (*xCmp)(Fts3SegReader *, Fts3SegReader *) = (
    p->bDescIdx ? fts3SegReaderDoclistCmpRev : fts3SegReaderDoclistCmp
  );

  assert( pCsr->pFilter==0 );
  assert( zTerm && nTerm>0 );

  /* Advance each segment iterator until it points to the term zTerm/nTerm. */
  rc = fts3SegReaderStart(p, pCsr, zTerm, nTerm);
  if( rc!=SQLITE_OK ) return rc;

  /* Determine how many of the segments actually point to zTerm/nTerm. */
  for(i=0; i<nSegment; i++){
    Fts3SegReader *pSeg = pCsr->apSegment[i];
    if( !pSeg->aNode || fts3SegReaderTermCmp(pSeg, zTerm, nTerm) ){
      break;
    }
  }
  pCsr->nAdvance = i;

  /* Advance each of the segments to point to the first docid. */
  for(i=0; i<pCsr->nAdvance; i++){
    rc = fts3SegReaderFirstDocid(p, pCsr->apSegment[i]);
    if( rc!=SQLITE_OK ) return rc;
  }
  fts3SegReaderSort(pCsr->apSegment, i, i, xCmp);


  assert( iCol<0 || iCol<p->nColumn );
  pCsr->iColFilter = iCol;

  return SQLITE_OK;
}

/*
** This function is called on a MultiSegReader that has been started using
** sqlite3Fts3MsrIncrStart(). One or more calls to MsrIncrNext() may also
** have been made. Calling this function puts the MultiSegReader in such
** a state that if the next two calls are:
**
**   sqlite3Fts3SegReaderStart()
**   sqlite3Fts3SegReaderStep()
**
** then the entire doclist for the term is available in 
** MultiSegReader.aDoclist/nDoclist.
*/
SQLITE_PRIVATE int sqlite3Fts3MsrIncrRestart(Fts3MultiSegReader *pCsr){
  int i;                          /* Used to iterate through segment-readers */

  assert( pCsr->zTerm==0 );
  assert( pCsr->nTerm==0 );
  assert( pCsr->aDoclist==0 );
  assert( pCsr->nDoclist==0 );

  pCsr->nAdvance = 0;
  pCsr->bRestart = 1;
  for(i=0; i<pCsr->nSegment; i++){
    pCsr->apSegment[i]->pOffsetList = 0;
    pCsr->apSegment[i]->nOffsetList = 0;
    pCsr->apSegment[i]->iDocid = 0;
  }

  return SQLITE_OK;
}


SQLITE_PRIVATE int sqlite3Fts3SegReaderStep(
  Fts3Table *p,                   /* Virtual table handle */
  Fts3MultiSegReader *pCsr        /* Cursor object */
){
  int rc = SQLITE_OK;

  int isIgnoreEmpty =  (pCsr->pFilter->flags & FTS3_SEGMENT_IGNORE_EMPTY);
  int isRequirePos =   (pCsr->pFilter->flags & FTS3_SEGMENT_REQUIRE_POS);
  int isColFilter =    (pCsr->pFilter->flags & FTS3_SEGMENT_COLUMN_FILTER);
  int isPrefix =       (pCsr->pFilter->flags & FTS3_SEGMENT_PREFIX);
  int isScan =         (pCsr->pFilter->flags & FTS3_SEGMENT_SCAN);

  Fts3SegReader **apSegment = pCsr->apSegment;
  int nSegment = pCsr->nSegment;
  Fts3SegFilter *pFilter = pCsr->pFilter;
  int (*xCmp)(Fts3SegReader *, Fts3SegReader *) = (
    p->bDescIdx ? fts3SegReaderDoclistCmpRev : fts3SegReaderDoclistCmp
  );

  if( pCsr->nSegment==0 ) return SQLITE_OK;

  do {
    int nMerge;
    int i;
  
    /* Advance the first pCsr->nAdvance entries in the apSegment[] array
    ** forward. Then sort the list in order of current term again.  
    */
    for(i=0; i<pCsr->nAdvance; i++){
      rc = fts3SegReaderNext(p, apSegment[i], 0);
      if( rc!=SQLITE_OK ) return rc;
    }
    fts3SegReaderSort(apSegment, nSegment, pCsr->nAdvance, fts3SegReaderCmp);
    pCsr->nAdvance = 0;

    /* If all the seg-readers are at EOF, we're finished. return SQLITE_OK. */
    assert( rc==SQLITE_OK );
................................................................................
        && apSegment[nMerge]->nTerm==pCsr->nTerm 
        && 0==memcmp(pCsr->zTerm, apSegment[nMerge]->zTerm, pCsr->nTerm)
    ){
      nMerge++;
    }

    assert( isIgnoreEmpty || (isRequirePos && !isColFilter) );
    if( nMerge==1 
     && !isIgnoreEmpty 
     && (p->bDescIdx==0 || fts3SegReaderIsPending(apSegment[0])==0)
    ){
      pCsr->nDoclist = apSegment[0]->nDoclist;
      if( fts3SegReaderIsPending(apSegment[0]) ){
        rc = fts3MsrBufferData(pCsr, apSegment[0]->aDoclist, pCsr->nDoclist);
        pCsr->aDoclist = pCsr->aBuffer;
      }else{
        pCsr->aDoclist = apSegment[0]->aDoclist;
      }
      if( rc==SQLITE_OK ) rc = SQLITE_ROW;
    }else{
      int nDoclist = 0;           /* Size of doclist */
      sqlite3_int64 iPrev = 0;    /* Previous docid stored in doclist */

      /* The current term of the first nMerge entries in the array
      ** of Fts3SegReader objects is the same. The doclists must be merged
      ** and a single term returned with the merged doclist.
      */
      for(i=0; i<nMerge; i++){
        fts3SegReaderFirstDocid(p, apSegment[i]);
      }
      fts3SegReaderSort(apSegment, nMerge, nMerge, xCmp);
      while( apSegment[0]->pOffsetList ){
        int j;                    /* Number of segments that share a docid */
        char *pList;
        int nList;
        int nByte;
        sqlite3_int64 iDocid = apSegment[0]->iDocid;
        fts3SegReaderNextDocid(p, apSegment[0], &pList, &nList);
        j = 1;
        while( j<nMerge
            && apSegment[j]->pOffsetList
            && apSegment[j]->iDocid==iDocid
        ){
          fts3SegReaderNextDocid(p, apSegment[j], 0, 0);
          j++;
        }

        if( isColFilter ){
          fts3ColumnFilter(pFilter->iCol, &pList, &nList);
        }

        if( !isIgnoreEmpty || nList>0 ){

          /* Calculate the 'docid' delta value to write into the merged 
          ** doclist. */
          sqlite3_int64 iDelta;
          if( p->bDescIdx && nDoclist>0 ){
            iDelta = iPrev - iDocid;
          }else{
            iDelta = iDocid - iPrev;
          }
          assert( iDelta>0 || (nDoclist==0 && iDelta==iDocid) );
          assert( nDoclist>0 || iDelta==iDocid );

          nByte = sqlite3Fts3VarintLen(iDelta) + (isRequirePos?nList+1:0);
          if( nDoclist+nByte>pCsr->nBuffer ){
            char *aNew;
            pCsr->nBuffer = (nDoclist+nByte)*2;
            aNew = sqlite3_realloc(pCsr->aBuffer, pCsr->nBuffer);
            if( !aNew ){
              return SQLITE_NOMEM;
            }
            pCsr->aBuffer = aNew;
          }
          nDoclist += sqlite3Fts3PutVarint(&pCsr->aBuffer[nDoclist], iDelta);


          iPrev = iDocid;
          if( isRequirePos ){
            memcpy(&pCsr->aBuffer[nDoclist], pList, nList);
            nDoclist += nList;
            pCsr->aBuffer[nDoclist++] = '\0';
          }
        }

        fts3SegReaderSort(apSegment, nMerge, j, xCmp);
      }
      if( nDoclist>0 ){
        pCsr->aDoclist = pCsr->aBuffer;
        pCsr->nDoclist = nDoclist;
        rc = SQLITE_ROW;
      }
    }
    pCsr->nAdvance = nMerge;
  }while( rc==SQLITE_OK );

  return rc;
}


SQLITE_PRIVATE void sqlite3Fts3SegReaderFinish(
  Fts3MultiSegReader *pCsr       /* Cursor object */
){
  if( pCsr ){
    int i;
    for(i=0; i<pCsr->nSegment; i++){
      sqlite3Fts3SegReaderFree(pCsr->apSegment[i]);
    }
    sqlite3_free(pCsr->apSegment);
................................................................................
** currently present in the database.
**
** If this function is called with iLevel<0, but there is only one
** segment in the database, SQLITE_DONE is returned immediately. 
** Otherwise, if successful, SQLITE_OK is returned. If an error occurs, 
** an SQLite error code is returned.
*/
static int fts3SegmentMerge(Fts3Table *p, int iIndex, int iLevel){
  int rc;                         /* Return code */
  int iIdx = 0;                   /* Index of new segment */
  int iNewLevel = 0;              /* Level/index to create new segment at */
  SegmentWriter *pWriter = 0;     /* Used to write the new, merged, segment */
  Fts3SegFilter filter;           /* Segment term filter condition */
  Fts3MultiSegReader csr;        /* Cursor to iterate through level(s) */
  int bIgnoreEmpty = 0;           /* True to ignore empty segments */

  assert( iLevel==FTS3_SEGCURSOR_ALL
       || iLevel==FTS3_SEGCURSOR_PENDING
       || iLevel>=0
  );
  assert( iLevel<FTS3_SEGDIR_MAXLEVEL );
  assert( iIndex>=0 && iIndex<p->nIndex );

  rc = sqlite3Fts3SegReaderCursor(p, iIndex, iLevel, 0, 0, 1, 0, &csr);
  if( rc!=SQLITE_OK || csr.nSegment==0 ) goto finished;

  if( iLevel==FTS3_SEGCURSOR_ALL ){
    /* This call is to merge all segments in the database to a single
    ** segment. The level of the new segment is equal to the the numerically 
    ** greatest segment level currently present in the database for this
    ** index. The idx of the new segment is always 0.  */

    if( csr.nSegment==1 ){
      rc = SQLITE_DONE;
      goto finished;
    }
    rc = fts3SegmentMaxLevel(p, iIndex, &iNewLevel);
    bIgnoreEmpty = 1;

  }else if( iLevel==FTS3_SEGCURSOR_PENDING ){
    iNewLevel = iIndex * FTS3_SEGDIR_MAXLEVEL; 
    rc = fts3AllocateSegdirIdx(p, iIndex, 0, &iIdx);
  }else{
    /* This call is to merge all segments at level iLevel. find the next
    ** available segment index at level iLevel+1. The call to
    ** fts3AllocateSegdirIdx() will merge the segments at level iLevel+1 to 
    ** a single iLevel+2 segment if necessary.  */
    rc = fts3AllocateSegdirIdx(p, iIndex, iLevel+1, &iIdx);
    iNewLevel = iIndex * FTS3_SEGDIR_MAXLEVEL + iLevel+1;
  }
  if( rc!=SQLITE_OK ) goto finished;
  assert( csr.nSegment>0 );
  assert( iNewLevel>=(iIndex*FTS3_SEGDIR_MAXLEVEL) );
  assert( iNewLevel<((iIndex+1)*FTS3_SEGDIR_MAXLEVEL) );

  memset(&filter, 0, sizeof(Fts3SegFilter));
  filter.flags = FTS3_SEGMENT_REQUIRE_POS;
  filter.flags |= (bIgnoreEmpty ? FTS3_SEGMENT_IGNORE_EMPTY : 0);

  rc = sqlite3Fts3SegReaderStart(p, &csr, &filter);
  while( SQLITE_OK==rc ){
    rc = sqlite3Fts3SegReaderStep(p, &csr);
    if( rc!=SQLITE_ROW ) break;
    rc = fts3SegWriterAdd(p, &pWriter, 1, 
        csr.zTerm, csr.nTerm, csr.aDoclist, csr.nDoclist);
  }
  if( rc!=SQLITE_OK ) goto finished;
  assert( pWriter );

  if( iLevel!=FTS3_SEGCURSOR_PENDING ){
    rc = fts3DeleteSegdir(p, iIndex, iLevel, csr.apSegment, csr.nSegment);
    if( rc!=SQLITE_OK ) goto finished;
  }
  rc = fts3SegWriterFlush(p, pWriter, iNewLevel, iIdx);

 finished:
  fts3SegWriterFree(pWriter);
  sqlite3Fts3SegReaderFinish(&csr);
  return rc;
}


/* 
** Flush the contents of pendingTerms to level 0 segments.
*/
SQLITE_PRIVATE int sqlite3Fts3PendingTermsFlush(Fts3Table *p){
  int rc = SQLITE_OK;
  int i;
  for(i=0; rc==SQLITE_OK && i<p->nIndex; i++){
    rc = fts3SegmentMerge(p, i, FTS3_SEGCURSOR_PENDING);
    if( rc==SQLITE_DONE ) rc = SQLITE_OK;
  }
  sqlite3Fts3PendingTermsClear(p);
  return rc;
}

/*
** Encode N integers as varints into a blob.
*/
static void fts3EncodeIntArray(
  int N,             /* The number of integers to encode */
................................................................................
    return;
  }
  sqlite3_bind_blob(pStmt, 1, pBlob, nBlob, SQLITE_STATIC);
  sqlite3_step(pStmt);
  *pRC = sqlite3_reset(pStmt);
  sqlite3_free(a);
}

static int fts3DoOptimize(Fts3Table *p, int bReturnDone){
  int i;
  int bSeenDone = 0;
  int rc = SQLITE_OK;
  for(i=0; rc==SQLITE_OK && i<p->nIndex; i++){
    rc = fts3SegmentMerge(p, i, FTS3_SEGCURSOR_ALL);
    if( rc==SQLITE_DONE ){
      bSeenDone = 1;
      rc = SQLITE_OK;
    }
  }
  sqlite3Fts3SegmentsClose(p);
  sqlite3Fts3PendingTermsClear(p);

  return (rc==SQLITE_OK && bReturnDone && bSeenDone) ? SQLITE_DONE : rc;
}

/*
** Handle a 'special' INSERT of the form:
**
**   "INSERT INTO tbl(tbl) VALUES(<expr>)"
**
** Argument pVal contains the result of <expr>. Currently the only 
................................................................................
  int rc;                         /* Return Code */
  const char *zVal = (const char *)sqlite3_value_text(pVal);
  int nVal = sqlite3_value_bytes(pVal);

  if( !zVal ){
    return SQLITE_NOMEM;
  }else if( nVal==8 && 0==sqlite3_strnicmp(zVal, "optimize", 8) ){
    rc = fts3DoOptimize(p, 0);





#ifdef SQLITE_TEST
  }else if( nVal>9 && 0==sqlite3_strnicmp(zVal, "nodesize=", 9) ){
    p->nNodeSize = atoi(&zVal[9]);
    rc = SQLITE_OK;
  }else if( nVal>11 && 0==sqlite3_strnicmp(zVal, "maxpending=", 9) ){
    p->nMaxPendingData = atoi(&zVal[11]);
    rc = SQLITE_OK;
#endif
  }else{
    rc = SQLITE_ERROR;
  }


  return rc;
}



































/*
** Delete all cached deferred doclists. Deferred doclists are cached
** (allocated) by the sqlite3Fts3CacheDeferredDoclists() function.
*/
SQLITE_PRIVATE void sqlite3Fts3FreeDeferredDoclists(Fts3Cursor *pCsr){
  Fts3DeferredToken *pDef;
  for(pDef=pCsr->pDeferred; pDef; pDef=pDef->pNext){
    fts3PendingListDelete(pDef->pList);
    pDef->pList = 0;
  }



}

/*
** Free all entries in the pCsr->pDeffered list. Entries are added to 
** this list using sqlite3Fts3DeferToken().
*/
SQLITE_PRIVATE void sqlite3Fts3FreeDeferredTokens(Fts3Cursor *pCsr){
  Fts3DeferredToken *pDef;
  Fts3DeferredToken *pNext;
  for(pDef=pCsr->pDeferred; pDef; pDef=pNext){
    pNext = pDef->pNext;
    fts3PendingListDelete(pDef->pList);
    sqlite3_free(pDef);
  }
  pCsr->pDeferred = 0;
}

/*
** Generate deferred-doclists for all tokens in the pCsr->pDeferred list
................................................................................
        rc = fts3PendingListAppendVarint(&pDef->pList, 0);
      }
    }
  }

  return rc;
}

SQLITE_PRIVATE int sqlite3Fts3DeferredTokenList(
  Fts3DeferredToken *p, 
  char **ppData, 
  int *pnData
){
  char *pRet;
  int nSkip;
  sqlite3_int64 dummy;

  *ppData = 0;
  *pnData = 0;

  if( p->pList==0 ){
    return SQLITE_OK;
  }

  pRet = (char *)sqlite3_malloc(p->pList->nData);
  if( !pRet ) return SQLITE_NOMEM;

  nSkip = sqlite3Fts3GetVarint(p->pList->aData, &dummy);
  *pnData = p->pList->nData - nSkip;
  *ppData = pRet;
  
  memcpy(pRet, &p->pList->aData[nSkip], *pnData);
  return SQLITE_OK;
}

/*
** Add an entry for token pToken to the pCsr->pDeferred list.
*/
SQLITE_PRIVATE int sqlite3Fts3DeferToken(
  Fts3Cursor *pCsr,               /* Fts3 table cursor */
  Fts3PhraseToken *pToken,        /* Token to defer */
................................................................................
  sqlite3_value **apVal,          /* Array of arguments */
  sqlite_int64 *pRowid            /* OUT: The affected (or effected) rowid */
){
  Fts3Table *p = (Fts3Table *)pVtab;
  int rc = SQLITE_OK;             /* Return Code */
  int isRemove = 0;               /* True for an UPDATE or DELETE */
  sqlite3_int64 iRemove = 0;      /* Rowid removed by UPDATE or DELETE */
  u32 *aSzIns = 0;                /* Sizes of inserted documents */
  u32 *aSzDel;                    /* Sizes of deleted documents */
  int nChng = 0;                  /* Net change in number of documents */
  int bInsertDone = 0;

  assert( p->pSegments==0 );

  /* Check for a "special" INSERT operation. One of the form:
................................................................................
  **
  **   INSERT INTO xyz(xyz) VALUES('command');
  */
  if( nArg>1 
   && sqlite3_value_type(apVal[0])==SQLITE_NULL 
   && sqlite3_value_type(apVal[p->nColumn+2])!=SQLITE_NULL 
  ){
    rc = fts3SpecialInsert(p, apVal[p->nColumn+2]);
    goto update_out;
  }

  /* Allocate space to hold the change in document sizes */
  aSzIns = sqlite3_malloc( sizeof(aSzIns[0])*(p->nColumn+1)*2 );
  if( aSzIns==0 ){
    rc = SQLITE_NOMEM;
    goto update_out;
  }
  aSzDel = &aSzIns[p->nColumn+1];
  memset(aSzIns, 0, sizeof(aSzIns[0])*(p->nColumn+1)*2);

  /* If this is an INSERT operation, or an UPDATE that modifies the rowid
  ** value, then this operation requires constraint handling.
  **
  ** If the on-conflict mode is REPLACE, this means that the existing row
................................................................................
      }else{
        rc = fts3InsertData(p, apVal, pRowid);
        bInsertDone = 1;
      }
    }
  }
  if( rc!=SQLITE_OK ){
    goto update_out;

  }

  /* If this is a DELETE or UPDATE operation, remove the old record. */
  if( sqlite3_value_type(apVal[0])!=SQLITE_NULL ){
    assert( sqlite3_value_type(apVal[0])==SQLITE_INTEGER );
    rc = fts3DeleteByRowid(p, apVal[0], &nChng, aSzDel);
    isRemove = 1;
................................................................................
    nChng++;
  }

  if( p->bHasStat ){
    fts3UpdateDocTotals(&rc, p, aSzIns, aSzDel, nChng);
  }

 update_out:
  sqlite3_free(aSzIns);
  sqlite3Fts3SegmentsClose(p);
  return rc;
}

/* 
** Flush any data in the pending-terms hash table to disk. If successful,
................................................................................
** merge all segments in the database (including the new segment, if 
** there was any data to flush) into a single segment. 
*/
SQLITE_PRIVATE int sqlite3Fts3Optimize(Fts3Table *p){
  int rc;
  rc = sqlite3_exec(p->db, "SAVEPOINT fts3", 0, 0, 0);
  if( rc==SQLITE_OK ){
    rc = fts3DoOptimize(p, 1);
    if( rc==SQLITE_OK || rc==SQLITE_DONE ){
      int rc2 = sqlite3_exec(p->db, "RELEASE fts3", 0, 0, 0);
      if( rc2!=SQLITE_OK ) rc = rc2;


    }else{
      sqlite3_exec(p->db, "ROLLBACK TO fts3", 0, 0, 0);
      sqlite3_exec(p->db, "RELEASE fts3", 0, 0, 0);
    }
  }
  sqlite3Fts3SegmentsClose(p);
  return rc;
................................................................................
  int (*x)(Fts3Expr*,int,void*),  /* Callback function to invoke for phrases */
  void *pCtx                      /* Second argument to pass to callback */
){
  int iPhrase = 0;                /* Variable used as the phrase counter */
  return fts3ExprIterate2(pExpr, &iPhrase, x, pCtx);
}














































/*
** This is an fts3ExprIterate() callback used while loading the doclists
** for each phrase into Fts3Expr.aDoclist[]/nDoclist. See also
** fts3ExprLoadDoclists().
*/
static int fts3ExprLoadDoclistsCb(Fts3Expr *pExpr, int iPhrase, void *ctx){
  int rc = SQLITE_OK;
  Fts3Phrase *pPhrase = pExpr->pPhrase;
  LoadDoclistCtx *p = (LoadDoclistCtx *)ctx;

  UNUSED_PARAMETER(iPhrase);

  p->nPhrase++;
  p->nToken += pPhrase->nToken;









  return rc;
}

/*
** Load the doclists for each phrase in the query associated with FTS3 cursor
** pCsr. 
................................................................................
static int fts3SnippetFindPositions(Fts3Expr *pExpr, int iPhrase, void *ctx){
  SnippetIter *p = (SnippetIter *)ctx;
  SnippetPhrase *pPhrase = &p->aPhrase[iPhrase];
  char *pCsr;

  pPhrase->nToken = pExpr->pPhrase->nToken;

  pCsr = sqlite3Fts3EvalPhrasePoslist(p->pCsr, pExpr, p->iCol);
  if( pCsr ){
    int iFirst = 0;
    pPhrase->pList = pCsr;
    fts3GetDeltaPosition(&pCsr, &iFirst);
    pPhrase->pHead = pCsr;
    pPhrase->pTail = pCsr;
    pPhrase->iHead = iFirst;
................................................................................
    if( !c ) nEntry++;
  }

  *ppCollist = pEnd;
  return nEntry;
}





















/*
** fts3ExprIterate() callback used to collect the "global" matchinfo stats
** for a single query. 
**
** fts3ExprIterate() callback to load the 'global' elements of a
** FTS3_MATCHINFO_HITS matchinfo array. The global stats are those elements 
** of the matchinfo array that are constant for all rows returned by the 
................................................................................
*/
static int fts3ExprGlobalHitsCb(
  Fts3Expr *pExpr,                /* Phrase expression node */
  int iPhrase,                    /* Phrase number (numbered from zero) */
  void *pCtx                      /* Pointer to MatchInfo structure */
){
  MatchInfo *p = (MatchInfo *)pCtx;
  return sqlite3Fts3EvalPhraseStats(



      p->pCursor, pExpr, &p->aMatchinfo[3*iPhrase*p->nCol]





































  );
}

/*
** fts3ExprIterate() callback used to collect the "local" part of the
** FTS3_MATCHINFO_HITS array. The local stats are those elements of the 
** array that are different for each row returned by the query.
*/
................................................................................
  int iPhrase,                    /* Phrase number */
  void *pCtx                      /* Pointer to MatchInfo structure */
){
  MatchInfo *p = (MatchInfo *)pCtx;
  int iStart = iPhrase * p->nCol * 3;
  int i;

  for(i=0; i<p->nCol; i++){
    char *pCsr;
    pCsr = sqlite3Fts3EvalPhrasePoslist(p->pCursor, pExpr, i);
    if( pCsr ){
      p->aMatchinfo[iStart+i*3] = fts3ColumnlistCount(&pCsr);
    }else{
      p->aMatchinfo[iStart+i*3] = 0;

    }
  }

  return SQLITE_OK;
}

static int fts3MatchinfoCheck(
................................................................................
** iterating through a multi-column position-list corresponding to the
** hits for a single phrase on a single row in order to calculate the
** values for a matchinfo() FTS3_MATCHINFO_LCS request.
*/
typedef struct LcsIterator LcsIterator;
struct LcsIterator {
  Fts3Expr *pExpr;                /* Pointer to phrase expression */

  int iPosOffset;                 /* Tokens count up to end of this phrase */

  char *pRead;                    /* Cursor used to iterate through aDoclist */
  int iPos;                       /* Current position */
};

/* 
** If LcsIterator.iCol is set to the following value, the iterator has
** finished iterating through all offsets for all columns.
*/
................................................................................
*/
static int fts3LcsIteratorAdvance(LcsIterator *pIter){
  char *pRead = pIter->pRead;
  sqlite3_int64 iRead;
  int rc = 0;

  pRead += sqlite3Fts3GetVarint(pRead, &iRead);
  if( iRead==0 || iRead==1 ){
    pRead = 0;
    rc = 1;
  }else{







    pIter->iPos += (int)(iRead-2);
  }

  pIter->pRead = pRead;
  return rc;
}
  
................................................................................
  /* Allocate and populate the array of LcsIterator objects. The array
  ** contains one element for each matchable phrase in the query.
  **/
  aIter = sqlite3_malloc(sizeof(LcsIterator) * pCsr->nPhrase);
  if( !aIter ) return SQLITE_NOMEM;
  memset(aIter, 0, sizeof(LcsIterator) * pCsr->nPhrase);
  (void)fts3ExprIterate(pCsr->pExpr, fts3MatchinfoLcsCb, (void*)aIter);

  for(i=0; i<pInfo->nPhrase; i++){
    LcsIterator *pIter = &aIter[i];
    nToken -= pIter->pExpr->pPhrase->nToken;
    pIter->iPosOffset = nToken;







  }

  for(iCol=0; iCol<pInfo->nCol; iCol++){
    int nLcs = 0;                 /* LCS value for this column */
    int nLive = 0;                /* Number of iterators in aIter not at EOF */

    for(i=0; i<pInfo->nPhrase; i++){
      LcsIterator *pIt = &aIter[i];
      pIt->pRead = sqlite3Fts3EvalPhrasePoslist(pCsr, pIt->pExpr, iCol);
      if( pIt->pRead ){
        pIt->iPos = pIt->iPosOffset;
        fts3LcsIteratorAdvance(&aIter[i]);
        nLive++;
      }
    }



    while( nLive>0 ){
      LcsIterator *pAdv = 0;      /* The iterator to advance by one position */
      int nThisLcs = 0;           /* LCS for the current iterator positions */

      for(i=0; i<pInfo->nPhrase; i++){
        LcsIterator *pIter = &aIter[i];
        if( pIter->pRead==0 ){
          /* This iterator is already at EOF for this column. */
          nThisLcs = 0;
        }else{
          if( pAdv==0 || pIter->iPos<pAdv->iPos ){
            pAdv = pIter;
          }
          if( nThisLcs==0 || pIter->iPos==pIter[-1].iPos ){
................................................................................

      case FTS3_MATCHINFO_NCOL:
        if( bGlobal ) pInfo->aMatchinfo[0] = pInfo->nCol;
        break;
        
      case FTS3_MATCHINFO_NDOC:
        if( bGlobal ){
          sqlite3_int64 nDoc = 0;
          rc = fts3MatchinfoSelectDoctotal(pTab, &pSelect, &nDoc, 0);
          pInfo->aMatchinfo[0] = (u32)nDoc;
        }
        break;

      case FTS3_MATCHINFO_AVGLENGTH: 
        if( bGlobal ){
................................................................................
  TermOffsetCtx *p = (TermOffsetCtx *)ctx;
  int nTerm;                      /* Number of tokens in phrase */
  int iTerm;                      /* For looping through nTerm phrase terms */
  char *pList;                    /* Pointer to position list for phrase */
  int iPos = 0;                   /* First position in position-list */

  UNUSED_PARAMETER(iPhrase);
  pList = sqlite3Fts3EvalPhrasePoslist(p->pCsr, pExpr, p->iCol);
  nTerm = pExpr->pPhrase->nToken;
  if( pList ){
    fts3GetDeltaPosition(&pList, &iPos);
    assert( iPos>=0 );
  }

  for(iTerm=0; iTerm<nTerm; iTerm++){
................................................................................
/*
** Return the N-dimensional volumn of the cell stored in *p.
*/
static float cellArea(Rtree *pRtree, RtreeCell *p){
  float area = 1.0;
  int ii;
  for(ii=0; ii<(pRtree->nDim*2); ii+=2){
    area = (float)(area * (DCOORD(p->aCoord[ii+1]) - DCOORD(p->aCoord[ii])));
  }
  return area;
}

/*
** Return the margin length of cell p. The margin length is the sum
** of the objects size in each dimension.
*/
static float cellMargin(Rtree *pRtree, RtreeCell *p){
  float margin = 0.0;
  int ii;
  for(ii=0; ii<(pRtree->nDim*2); ii+=2){
    margin += (float)(DCOORD(p->aCoord[ii+1]) - DCOORD(p->aCoord[ii]));
  }
  return margin;
}

/*
** Store the union of cells p1 and p2 in p1.
*/
................................................................................
        x1 = MAX(DCOORD(p->aCoord[jj]), DCOORD(aCell[ii].aCoord[jj]));
        x2 = MIN(DCOORD(p->aCoord[jj+1]), DCOORD(aCell[ii].aCoord[jj+1]));

        if( x2<x1 ){
          o = 0.0;
          break;
        }else{
          o = o * (float)(x2-x1);
        }
      }
      overlap += o;
    }
  }
  return overlap;
}
................................................................................
  Rtree *pRtree, 
  RtreeCell *p, 
  RtreeCell *pInsert, 
  RtreeCell *aCell, 
  int nCell, 
  int iExclude
){
  double before;
  double after;
  before = cellOverlap(pRtree, p, aCell, nCell, iExclude);
  cellUnion(pRtree, p, pInsert);
  after = cellOverlap(pRtree, p, aCell, nCell, iExclude);
  return (float)(after-before);
}
#endif


/*
** This function implements the ChooseLeaf algorithm from Gutman[84].
** ChooseSubTree in r*tree terminology.
................................................................................
  int rc;
  int ii;
  RtreeNode *pNode;
  rc = nodeAcquire(pRtree, 1, 0, &pNode);

  for(ii=0; rc==SQLITE_OK && ii<(pRtree->iDepth-iHeight); ii++){
    int iCell;
    sqlite3_int64 iBest = 0;

    float fMinGrowth = 0.0;
    float fMinArea = 0.0;
    float fMinOverlap = 0.0;

    int nCell = NCELL(pNode);
    RtreeCell cell;
    RtreeNode *pChild;

    RtreeCell *aCell = 0;

................................................................................
  RtreeCell *pBboxLeft,
  RtreeCell *pBboxRight
){
  int **aaSorted;
  int *aSpare;
  int ii;

  int iBestDim = 0;
  int iBestSplit = 0;
  float fBestMargin = 0.0;

  int nByte = (pRtree->nDim+1)*(sizeof(int*)+nCell*sizeof(int));

  aaSorted = (int **)sqlite3_malloc(nByte);
  if( !aaSorted ){
    return SQLITE_NOMEM;
  }
................................................................................
      aaSorted[ii][jj] = jj;
    }
    SortByDimension(pRtree, aaSorted[ii], nCell, ii, aCell, aSpare);
  }

  for(ii=0; ii<pRtree->nDim; ii++){
    float margin = 0.0;
    float fBestOverlap = 0.0;
    float fBestArea = 0.0;
    int iBestLeft = 0;
    int nLeft;

    for(
      nLeft=RTREE_MINCELLS(pRtree); 
      nLeft<=(nCell-RTREE_MINCELLS(pRtree)); 
      nLeft++
    ){
................................................................................
}

static int deleteCell(Rtree *, RtreeNode *, int, int);

static int removeNode(Rtree *pRtree, RtreeNode *pNode, int iHeight){
  int rc;
  int rc2;
  RtreeNode *pParent = 0;
  int iCell;

  assert( pNode->nRef==1 );

  /* Remove the entry in the parent cell. */
  rc = nodeParentIndex(pRtree, pNode, &iCell);
  if( rc==SQLITE_OK ){
................................................................................
    if( ii==(nCell-1) ){
      memcpy(&aCell[ii], pCell, sizeof(RtreeCell));
    }else{
      nodeGetCell(pRtree, pNode, ii, &aCell[ii]);
    }
    aOrder[ii] = ii;
    for(iDim=0; iDim<pRtree->nDim; iDim++){
      aCenterCoord[iDim] += (float)DCOORD(aCell[ii].aCoord[iDim*2]);
      aCenterCoord[iDim] += (float)DCOORD(aCell[ii].aCoord[iDim*2+1]);
    }
  }
  for(iDim=0; iDim<pRtree->nDim; iDim++){
    aCenterCoord[iDim] = (float)(aCenterCoord[iDim]/((float)nCell*2.0));
  }

  for(ii=0; ii<nCell; ii++){
    aDistance[ii] = 0.0;
    for(iDim=0; iDim<pRtree->nDim; iDim++){
      float coord = (float)(DCOORD(aCell[ii].aCoord[iDim*2+1]) - 
          DCOORD(aCell[ii].aCoord[iDim*2]));
      aDistance[ii] += (coord-aCenterCoord[iDim])*(coord-aCenterCoord[iDim]);
    }
  }

  SortByDistance(aOrder, nCell, aDistance, aSpare);
  nodeZero(pRtree, pNode);

................................................................................
    RtreeNode *pInsert;
    RtreeCell cell;
    nodeGetCell(pRtree, pNode, ii, &cell);

    /* Find a node to store this cell in. pNode->iNode currently contains
    ** the height of the sub-tree headed by the cell.
    */
    rc = ChooseLeaf(pRtree, &cell, (int)pNode->iNode, &pInsert);
    if( rc==SQLITE_OK ){
      int rc2;
      rc = rtreeInsertCell(pRtree, pInsert, &cell, (int)pNode->iNode);
      rc2 = nodeRelease(pRtree, pInsert);
      if( rc==SQLITE_OK ){
        rc = rc2;
      }
    }
  }
  return rc;
................................................................................
  sqlite3 *db,                    /* Database handle */
  Rtree *pRtree,                  /* Rtree handle */
  int isCreate                    /* True for xCreate, false for xConnect */
){
  int rc;
  char *zSql;
  if( isCreate ){
    int iPageSize = 0;
    zSql = sqlite3_mprintf("PRAGMA %Q.page_size", pRtree->zDb);
    rc = getIntFromStmt(db, zSql, &iPageSize);
    if( rc==SQLITE_OK ){
      pRtree->iNodeSize = iPageSize-64;
      if( (4+pRtree->nBytesPerCell*RTREE_MAXCELLS)<pRtree->iNodeSize ){
        pRtree->iNodeSize = 4+pRtree->nBytesPerCell*RTREE_MAXCELLS;
      }
................................................................................
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file implements a tokenizer for fts3 based on the ICU library.


*/

#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
#ifdef SQLITE_ENABLE_ICU


#include <unicode/ubrk.h>
#include <unicode/utf16.h>

**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.7.7"
#define SQLITE_VERSION_NUMBER 3007007
#define SQLITE_SOURCE_ID      "2011-05-25 23:18:02 a4755e7088c3cc7c5ea191ce37f3950472f523ec"

/*
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version, sqlite3_sourceid
**
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
................................................................................
**
** ^The sqlite3_exec() interface runs zero or more UTF-8 encoded,
** semicolon-separate SQL statements passed into its 2nd argument,
** in the context of the [database connection] passed in as its 1st
** argument.  ^If the callback function of the 3rd argument to
** sqlite3_exec() is not NULL, then it is invoked for each result row
** coming out of the evaluated SQL statements.  ^The 4th argument to
** to sqlite3_exec() is relayed through to the 1st argument of each
** callback invocation.  ^If the callback pointer to sqlite3_exec()
** is NULL, then no callback is ever invoked and result rows are
** ignored.
**
** ^If an error occurs while evaluating the SQL statements passed into
** sqlite3_exec(), then execution of the current statement stops and
** subsequent statements are skipped.  ^If the 5th parameter to sqlite3_exec()
................................................................................
#define SQLITE_IOERR_SHMLOCK           (SQLITE_IOERR | (20<<8))
#define SQLITE_IOERR_SHMMAP            (SQLITE_IOERR | (21<<8))
#define SQLITE_IOERR_SEEK              (SQLITE_IOERR | (22<<8))
#define SQLITE_LOCKED_SHAREDCACHE      (SQLITE_LOCKED |  (1<<8))
#define SQLITE_BUSY_RECOVERY           (SQLITE_BUSY   |  (1<<8))
#define SQLITE_CANTOPEN_NOTEMPDIR      (SQLITE_CANTOPEN | (1<<8))
#define SQLITE_CORRUPT_VTAB            (SQLITE_CORRUPT | (1<<8))



/*
** CAPI3REF: Flags For File Open Operations
**
** These bit values are intended for use in the
** 3rd parameter to the [sqlite3_open_v2()] interface and
** in the 4th parameter to the [sqlite3_vfs.xOpen] method.
................................................................................
** of good-quality randomness into zOut.  The return value is
** the actual number of bytes of randomness obtained.
** The xSleep() method causes the calling thread to sleep for at
** least the number of microseconds given.  ^The xCurrentTime()
** method returns a Julian Day Number for the current date and time as
** a floating point value.
** ^The xCurrentTimeInt64() method returns, as an integer, the Julian
** Day Number multipled by 86400000 (the number of milliseconds in 
** a 24-hour day).  
** ^SQLite will use the xCurrentTimeInt64() method to get the current
** date and time if that method is available (if iVersion is 2 or 
** greater and the function pointer is not NULL) and will fall back
** to xCurrentTime() if xCurrentTimeInt64() is unavailable.
**
** ^The xSetSystemCall(), xGetSystemCall(), and xNestSystemCall() interfaces
................................................................................
** ^SQLite will never require a scratch buffer that is more than 6
** times the database page size. ^If SQLite needs needs additional
** scratch memory beyond what is provided by this configuration option, then 
** [sqlite3_malloc()] will be used to obtain the memory needed.</dd>
**
** [[SQLITE_CONFIG_PAGECACHE]] <dt>SQLITE_CONFIG_PAGECACHE</dt>
** <dd> ^This option specifies a static memory buffer that SQLite can use for
** the database page cache with the default page cache implemenation.  
** This configuration should not be used if an application-define page
** cache implementation is loaded using the SQLITE_CONFIG_PCACHE option.
** There are three arguments to this option: A pointer to 8-byte aligned
** memory, the size of each page buffer (sz), and the number of pages (N).
** The sz argument should be the size of the largest database page
** (a power of two between 512 and 32768) plus a little extra for each
** page header.  ^The page header size is 20 to 40 bytes depending on
................................................................................
** automatically deleted as soon as the database connection is closed.
**
** [[URI filenames in sqlite3_open()]] <h3>URI Filenames</h3>
**
** ^If [URI filename] interpretation is enabled, and the filename argument
** begins with "file:", then the filename is interpreted as a URI. ^URI
** filename interpretation is enabled if the [SQLITE_OPEN_URI] flag is
** is set in the fourth argument to sqlite3_open_v2(), or if it has
** been enabled globally using the [SQLITE_CONFIG_URI] option with the
** [sqlite3_config()] method or by the [SQLITE_USE_URI] compile-time option.
** As of SQLite version 3.7.7, URI filename interpretation is turned off
** by default, but future releases of SQLite might enable URI filename
** intepretation by default.  See "[URI filenames]" for additional
** information.
**
** URI filenames are parsed according to RFC 3986. ^If the URI contains an
** authority, then it must be either an empty string or the string 
** "localhost". ^If the authority is not an empty string or "localhost", an 
** error is returned to the caller. ^The fragment component of a URI, if 
** present, is ignored.
................................................................................
** [SQLITE_DONE], [SQLITE_ROW], [SQLITE_ERROR], or [SQLITE_MISUSE].
** ^With the "v2" interface, any of the other [result codes] or
** [extended result codes] might be returned as well.
**
** ^[SQLITE_BUSY] means that the database engine was unable to acquire the
** database locks it needs to do its job.  ^If the statement is a [COMMIT]
** or occurs outside of an explicit transaction, then you can retry the
** statement.  If the statement is not a [COMMIT] and occurs within a
** explicit transaction then you should rollback the transaction before
** continuing.
**
** ^[SQLITE_DONE] means that the statement has finished executing
** successfully.  sqlite3_step() should not be called again on this virtual
** machine without first calling [sqlite3_reset()] to reset the virtual
** machine back to its initial state.
................................................................................
SQLITE_API int sqlite3_column_type(sqlite3_stmt*, int iCol);
SQLITE_API sqlite3_value *sqlite3_column_value(sqlite3_stmt*, int iCol);

/*
** CAPI3REF: Destroy A Prepared Statement Object
**
** ^The sqlite3_finalize() function is called to delete a [prepared statement].
** ^If the most recent evaluation of the statement encountered no errors or
** or if the statement is never been evaluated, then sqlite3_finalize() returns
** SQLITE_OK.  ^If the most recent evaluation of statement S failed, then
** sqlite3_finalize(S) returns the appropriate [error code] or
** [extended error code].
**
** ^The sqlite3_finalize(S) routine can be called at any point during
** the life cycle of [prepared statement] S:
................................................................................
** ^The implementation is not required to provided versions of these
** routines that actually work. If the implementation does not provide working
** versions of these routines, it should at least provide stubs that always
** return true so that one does not get spurious assertion failures.
**
** ^If the argument to sqlite3_mutex_held() is a NULL pointer then
** the routine should return 1.   This seems counter-intuitive since
** clearly the mutex cannot be held if it does not exist.  But the
** the reason the mutex does not exist is because the build is not
** using mutexes.  And we do not want the assert() containing the
** call to sqlite3_mutex_held() to fail, so a non-zero return is
** the appropriate thing to do.  ^The sqlite3_mutex_notheld()
** interface should also return 1 when given a NULL pointer.
*/
#ifndef NDEBUG
................................................................................
#define SQLITE_TESTCTRL_ASSERT                  12
#define SQLITE_TESTCTRL_ALWAYS                  13
#define SQLITE_TESTCTRL_RESERVE                 14
#define SQLITE_TESTCTRL_OPTIMIZATIONS           15
#define SQLITE_TESTCTRL_ISKEYWORD               16
#define SQLITE_TESTCTRL_PGHDRSZ                 17
#define SQLITE_TESTCTRL_SCRATCHMALLOC           18

#define SQLITE_TESTCTRL_LAST                    18

/*
** CAPI3REF: SQLite Runtime Status
**
** ^This interface is used to retrieve runtime status information
** about the performance of SQLite, and optionally to reset various
** highwater marks.  ^The first argument is an integer code for
................................................................................
** stored in the cache, both pinned and unpinned.
** 
** [[the xFetch() page cache methods]]
** The xFetch() method locates a page in the cache and returns a pointer to 
** the page, or a NULL pointer.
** A "page", in this context, means a buffer of szPage bytes aligned at an
** 8-byte boundary. The page to be fetched is determined by the key. ^The
** mimimum key value is 1.  After it has been retrieved using xFetch, the page 
** is considered to be "pinned".
**
** If the requested page is already in the page cache, then the page cache
** implementation must return a pointer to the page buffer with its content
** intact.  If the requested page is not already in the cache, then the
** cache implementation should use the value of the createFlag
** parameter to help it determined what action to take:

**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.7.7"
#define SQLITE_VERSION_NUMBER 3007007
#define SQLITE_SOURCE_ID      "2011-06-23 17:29:33 b61a76a53af04f731fe7617f7b6b4fb2aef6587b"

/*
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version, sqlite3_sourceid
**
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
................................................................................
**
** ^The sqlite3_exec() interface runs zero or more UTF-8 encoded,
** semicolon-separate SQL statements passed into its 2nd argument,
** in the context of the [database connection] passed in as its 1st
** argument.  ^If the callback function of the 3rd argument to
** sqlite3_exec() is not NULL, then it is invoked for each result row
** coming out of the evaluated SQL statements.  ^The 4th argument to
** sqlite3_exec() is relayed through to the 1st argument of each
** callback invocation.  ^If the callback pointer to sqlite3_exec()
** is NULL, then no callback is ever invoked and result rows are
** ignored.
**
** ^If an error occurs while evaluating the SQL statements passed into
** sqlite3_exec(), then execution of the current statement stops and
** subsequent statements are skipped.  ^If the 5th parameter to sqlite3_exec()
................................................................................
#define SQLITE_IOERR_SHMLOCK           (SQLITE_IOERR | (20<<8))
#define SQLITE_IOERR_SHMMAP            (SQLITE_IOERR | (21<<8))
#define SQLITE_IOERR_SEEK              (SQLITE_IOERR | (22<<8))
#define SQLITE_LOCKED_SHAREDCACHE      (SQLITE_LOCKED |  (1<<8))
#define SQLITE_BUSY_RECOVERY           (SQLITE_BUSY   |  (1<<8))
#define SQLITE_CANTOPEN_NOTEMPDIR      (SQLITE_CANTOPEN | (1<<8))
#define SQLITE_CORRUPT_VTAB            (SQLITE_CORRUPT | (1<<8))
#define SQLITE_READONLY_RECOVERY       (SQLITE_READONLY | (1<<8))
#define SQLITE_READONLY_CANTLOCK       (SQLITE_READONLY | (2<<8))

/*
** CAPI3REF: Flags For File Open Operations
**
** These bit values are intended for use in the
** 3rd parameter to the [sqlite3_open_v2()] interface and
** in the 4th parameter to the [sqlite3_vfs.xOpen] method.
................................................................................
** of good-quality randomness into zOut.  The return value is
** the actual number of bytes of randomness obtained.
** The xSleep() method causes the calling thread to sleep for at
** least the number of microseconds given.  ^The xCurrentTime()
** method returns a Julian Day Number for the current date and time as
** a floating point value.
** ^The xCurrentTimeInt64() method returns, as an integer, the Julian
** Day Number multiplied by 86400000 (the number of milliseconds in 
** a 24-hour day).  
** ^SQLite will use the xCurrentTimeInt64() method to get the current
** date and time if that method is available (if iVersion is 2 or 
** greater and the function pointer is not NULL) and will fall back
** to xCurrentTime() if xCurrentTimeInt64() is unavailable.
**
** ^The xSetSystemCall(), xGetSystemCall(), and xNestSystemCall() interfaces
................................................................................
** ^SQLite will never require a scratch buffer that is more than 6
** times the database page size. ^If SQLite needs needs additional
** scratch memory beyond what is provided by this configuration option, then 
** [sqlite3_malloc()] will be used to obtain the memory needed.</dd>
**
** [[SQLITE_CONFIG_PAGECACHE]] <dt>SQLITE_CONFIG_PAGECACHE</dt>
** <dd> ^This option specifies a static memory buffer that SQLite can use for
** the database page cache with the default page cache implementation.  
** This configuration should not be used if an application-define page
** cache implementation is loaded using the SQLITE_CONFIG_PCACHE option.
** There are three arguments to this option: A pointer to 8-byte aligned
** memory, the size of each page buffer (sz), and the number of pages (N).
** The sz argument should be the size of the largest database page
** (a power of two between 512 and 32768) plus a little extra for each
** page header.  ^The page header size is 20 to 40 bytes depending on
................................................................................
** automatically deleted as soon as the database connection is closed.
**
** [[URI filenames in sqlite3_open()]] <h3>URI Filenames</h3>
**
** ^If [URI filename] interpretation is enabled, and the filename argument
** begins with "file:", then the filename is interpreted as a URI. ^URI
** filename interpretation is enabled if the [SQLITE_OPEN_URI] flag is
** set in the fourth argument to sqlite3_open_v2(), or if it has
** been enabled globally using the [SQLITE_CONFIG_URI] option with the
** [sqlite3_config()] method or by the [SQLITE_USE_URI] compile-time option.
** As of SQLite version 3.7.7, URI filename interpretation is turned off
** by default, but future releases of SQLite might enable URI filename
** interpretation by default.  See "[URI filenames]" for additional
** information.
**
** URI filenames are parsed according to RFC 3986. ^If the URI contains an
** authority, then it must be either an empty string or the string 
** "localhost". ^If the authority is not an empty string or "localhost", an 
** error is returned to the caller. ^The fragment component of a URI, if 
** present, is ignored.
................................................................................
** [SQLITE_DONE], [SQLITE_ROW], [SQLITE_ERROR], or [SQLITE_MISUSE].
** ^With the "v2" interface, any of the other [result codes] or
** [extended result codes] might be returned as well.
**
** ^[SQLITE_BUSY] means that the database engine was unable to acquire the
** database locks it needs to do its job.  ^If the statement is a [COMMIT]
** or occurs outside of an explicit transaction, then you can retry the
** statement.  If the statement is not a [COMMIT] and occurs within an
** explicit transaction then you should rollback the transaction before
** continuing.
**
** ^[SQLITE_DONE] means that the statement has finished executing
** successfully.  sqlite3_step() should not be called again on this virtual
** machine without first calling [sqlite3_reset()] to reset the virtual
** machine back to its initial state.
................................................................................
SQLITE_API int sqlite3_column_type(sqlite3_stmt*, int iCol);
SQLITE_API sqlite3_value *sqlite3_column_value(sqlite3_stmt*, int iCol);

/*
** CAPI3REF: Destroy A Prepared Statement Object
**
** ^The sqlite3_finalize() function is called to delete a [prepared statement].
** ^If the most recent evaluation of the statement encountered no errors
** or if the statement is never been evaluated, then sqlite3_finalize() returns
** SQLITE_OK.  ^If the most recent evaluation of statement S failed, then
** sqlite3_finalize(S) returns the appropriate [error code] or
** [extended error code].
**
** ^The sqlite3_finalize(S) routine can be called at any point during
** the life cycle of [prepared statement] S:
................................................................................
** ^The implementation is not required to provided versions of these
** routines that actually work. If the implementation does not provide working
** versions of these routines, it should at least provide stubs that always
** return true so that one does not get spurious assertion failures.
**
** ^If the argument to sqlite3_mutex_held() is a NULL pointer then
** the routine should return 1.   This seems counter-intuitive since
** clearly the mutex cannot be held if it does not exist.  But
** the reason the mutex does not exist is because the build is not
** using mutexes.  And we do not want the assert() containing the
** call to sqlite3_mutex_held() to fail, so a non-zero return is
** the appropriate thing to do.  ^The sqlite3_mutex_notheld()
** interface should also return 1 when given a NULL pointer.
*/
#ifndef NDEBUG
................................................................................
#define SQLITE_TESTCTRL_ASSERT                  12
#define SQLITE_TESTCTRL_ALWAYS                  13
#define SQLITE_TESTCTRL_RESERVE                 14
#define SQLITE_TESTCTRL_OPTIMIZATIONS           15
#define SQLITE_TESTCTRL_ISKEYWORD               16
#define SQLITE_TESTCTRL_PGHDRSZ                 17
#define SQLITE_TESTCTRL_SCRATCHMALLOC           18
#define SQLITE_TESTCTRL_LOCALTIME_FAULT         19
#define SQLITE_TESTCTRL_LAST                    19

/*
** CAPI3REF: SQLite Runtime Status
**
** ^This interface is used to retrieve runtime status information
** about the performance of SQLite, and optionally to reset various
** highwater marks.  ^The first argument is an integer code for
................................................................................
** stored in the cache, both pinned and unpinned.
** 
** [[the xFetch() page cache methods]]
** The xFetch() method locates a page in the cache and returns a pointer to 
** the page, or a NULL pointer.
** A "page", in this context, means a buffer of szPage bytes aligned at an
** 8-byte boundary. The page to be fetched is determined by the key. ^The
** minimum key value is 1.  After it has been retrieved using xFetch, the page 
** is considered to be "pinned".
**
** If the requested page is already in the page cache, then the page cache
** implementation must return a pointer to the page buffer with its content
** intact.  If the requested page is not already in the cache, then the
** cache implementation should use the value of the createFlag
** parameter to help it determined what action to take: