SQLite

  Fts3Table *p = (Fts3Table *)pVtab;
  int i;

  assert( p->nPendingData==0 );
  assert( p->pSegments==0 );

  /* Free any prepared statements held */
  sqlite3_finalize(p->pSeekStmt);
  for(i=0; i<SizeofArray(p->aStmt); i++){
    sqlite3_finalize(p->aStmt[i]);
  }
  sqlite3_free(p->zSegmentsTbl);
  sqlite3_free(p->zReadExprlist);
  sqlite3_free(p->zWriteExprlist);
  sqlite3_free(p->zContentTbl);

  *ppCsr = pCsr = (sqlite3_vtab_cursor *)sqlite3_malloc(sizeof(Fts3Cursor));
  if( !pCsr ){
    return SQLITE_NOMEM;
  }
  memset(pCsr, 0, sizeof(Fts3Cursor));
  return SQLITE_OK;
}

/*
** Finalize the statement handle at pCsr->pStmt.
**
** Or, if that statement handle is one created by fts3CursorSeekStmt(),
** and the Fts3Table.pSeekStmt slot is currently NULL, save the statement
** pointer there instead of finalizing it.
*/
static void fts3CursorFinalizeStmt(Fts3Cursor *pCsr){
  if( pCsr->bSeekStmt ){
    Fts3Table *p = (Fts3Table *)pCsr->base.pVtab;
    if( p->pSeekStmt==0 ){
      p->pSeekStmt = pCsr->pStmt;
      sqlite3_reset(pCsr->pStmt);
      pCsr->pStmt = 0;
    }
    pCsr->bSeekStmt = 0;
  }
  sqlite3_finalize(pCsr->pStmt);
}

/*
** Close the cursor.  For additional information see the documentation
** on the xClose method of the virtual table interface.
*/
static int fts3CloseMethod(sqlite3_vtab_cursor *pCursor){
  Fts3Cursor *pCsr = (Fts3Cursor *)pCursor;
  assert( ((Fts3Table *)pCsr->base.pVtab)->pSegments==0 );
  fts3CursorFinalizeStmt(pCsr);
  sqlite3Fts3ExprFree(pCsr->pExpr);
  sqlite3Fts3FreeDeferredTokens(pCsr);
  sqlite3_free(pCsr->aDoclist);
  sqlite3Fts3MIBufferFree(pCsr->pMIBuffer);
  assert( ((Fts3Table *)pCsr->base.pVtab)->pSegments==0 );
  sqlite3_free(pCsr);
  return SQLITE_OK;
}

/*
** If pCsr->pStmt has not been prepared (i.e. if pCsr->pStmt==0), then
** compose and prepare an SQL statement of the form:
**
**    "SELECT <columns> FROM %_content WHERE rowid = ?"
**
** (or the equivalent for a content=xxx table) and set pCsr->pStmt to
** it. If an error occurs, return an SQLite error code.


*/
static int fts3CursorSeekStmt(Fts3Cursor *pCsr){
  int rc = SQLITE_OK;
  if( pCsr->pStmt==0 ){
    Fts3Table *p = (Fts3Table *)pCsr->base.pVtab;
    char *zSql;
    if( p->pSeekStmt ){
      pCsr->pStmt = p->pSeekStmt;
      p->pSeekStmt = 0;
    }else{
      zSql = sqlite3_mprintf("SELECT %s WHERE rowid = ?", p->zReadExprlist);
      if( !zSql ) return SQLITE_NOMEM;
      rc = sqlite3_prepare_v2(p->db, zSql, -1, &pCsr->pStmt, 0);
      sqlite3_free(zSql);
    }
    if( rc==SQLITE_OK ) pCsr->bSeekStmt = 1;
  }
  return rc;
}

/*
** 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){
  int rc = SQLITE_OK;
  if( pCsr->isRequireSeek ){


    rc = fts3CursorSeekStmt(pCsr);
    if( rc==SQLITE_OK ){
      sqlite3_bind_int64(pCsr->pStmt, 1, pCsr->iPrevId);
      pCsr->isRequireSeek = 0;
      if( SQLITE_ROW==sqlite3_step(pCsr->pStmt) ){
        return SQLITE_OK;
      }else{
        rc = sqlite3_reset(pCsr->pStmt);

  if( eSearch!=FTS3_FULLSCAN_SEARCH ) pCons = apVal[iIdx++];
  if( idxNum & FTS3_HAVE_LANGID ) pLangid = apVal[iIdx++];
  if( idxNum & FTS3_HAVE_DOCID_GE ) pDocidGe = apVal[iIdx++];
  if( idxNum & FTS3_HAVE_DOCID_LE ) pDocidLe = apVal[iIdx++];
  assert( iIdx==nVal );

  /* In case the cursor has been used before, clear it now. */
  fts3CursorFinalizeStmt(pCsr);
  sqlite3_free(pCsr->aDoclist);
  sqlite3Fts3MIBufferFree(pCsr->pMIBuffer);
  sqlite3Fts3ExprFree(pCsr->pExpr);
  memset(&pCursor[1], 0, sizeof(Fts3Cursor)-sizeof(sqlite3_vtab_cursor));

  /* Set the lower and upper bounds on docids to return */
  pCsr->iMinDocid = fts3DocidRange(pDocidGe, SMALLEST_INT64);

    if( zSql ){
      rc = sqlite3_prepare_v2(p->db, zSql, -1, &pCsr->pStmt, 0);
      sqlite3_free(zSql);
    }else{
      rc = SQLITE_NOMEM;
    }
  }else if( eSearch==FTS3_DOCID_SEARCH ){
    rc = fts3CursorSeekStmt(pCsr);
    if( rc==SQLITE_OK ){
      rc = sqlite3_bind_value(pCsr->pStmt, 1, pCons);
    }
  }
  if( rc!=SQLITE_OK ) return rc;

  return fts3NextMethod(pCursor);

  int nAutoincrmerge;             /* Value configured by 'automerge' */
  u32 nLeafAdd;                   /* Number of leaf blocks added this trans */

  /* Precompiled statements used by the implementation. Each of these 
  ** statements is run and reset within a single virtual table API call. 
  */
  sqlite3_stmt *aStmt[40];
  sqlite3_stmt *pSeekStmt;        /* Cache for fts3CursorSeekStmt() */

  char *zReadExprlist;
  char *zWriteExprlist;

  int nNodeSize;                  /* Soft limit for node size */
  u8 bFts4;                       /* True for FTS4, false for FTS3 */
  u8 bHasStat;                    /* True if %_stat table exists (2==unknown) */

** the xOpen method. Cursors are destroyed using the xClose method.
*/
struct Fts3Cursor {
  sqlite3_vtab_cursor base;       /* Base class used by SQLite core */
  i16 eSearch;                    /* Search strategy (see below) */
  u8 isEof;                       /* True if at End Of Results */
  u8 isRequireSeek;               /* True if must seek pStmt to %_content row */
  u8 bSeekStmt;                   /* True if pStmt is a seek */
  sqlite3_stmt *pStmt;            /* Prepared statement in use by the cursor */
  Fts3Expr *pExpr;                /* Parsed MATCH query string */
  int iLangid;                    /* Language being queried for */
  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 */

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

/* What version of GCC is being used.  0 means GCC is not being used */
#ifndef GCC_VERSION
#if defined(__GNUC__) && !defined(SQLITE_DISABLE_INTRINSIC)
# define GCC_VERSION (__GNUC__*1000000+__GNUC_MINOR__*1000+__GNUC_PATCHLEVEL__)
#else
# define GCC_VERSION 0
#endif
#endif

/* What version of CLANG is being used.  0 means CLANG is not being used */
#ifndef CLANG_VERSION
#if defined(__clang__) && !defined(_WIN32) && !defined(SQLITE_DISABLE_INTRINSIC)
# define CLANG_VERSION \
            (__clang_major__*1000000+__clang_minor__*1000+__clang_patchlevel__)
#else
# define CLANG_VERSION 0
#endif
#endif

**
** For best performance, an attempt is made to guess at the byte-order
** using C-preprocessor macros.  If that is unsuccessful, or if
** -DSQLITE_RUNTIME_BYTEORDER=1 is set, then byte-order is determined
** at run-time.
*/
#ifndef SQLITE_BYTEORDER
#if defined(i386)     || defined(__i386__)   || defined(_M_IX86) ||    \
    defined(__x86_64) || defined(__x86_64__) || defined(_M_X64)  ||    \
    defined(_M_AMD64) || defined(_M_ARM)     || defined(__x86)   ||    \
    defined(__arm__)
# define SQLITE_BYTEORDER    1234
#elif defined(sparc)    || defined(__ppc__)

# define SQLITE_BYTEORDER    4321
#else
# define SQLITE_BYTEORDER    0     /* 0 means "unknown at compile-time" */
#endif
#endif


/* What version of MSVC is being used.  0 means MSVC is not being used */
#ifndef MSVC_VERSION
#if defined(_MSC_VER) && !defined(SQLITE_DISABLE_INTRINSIC)
# define MSVC_VERSION _MSC_VER
#else
# define MSVC_VERSION 0
#endif
#endif

/*
** Functions to deserialize a 16 bit integer, 32 bit real number and
** 64 bit integer. The deserialized value is returned.
*/
static int readInt16(u8 *p){
  return (p[0]<<8) + p[1];
}
static void readCoord(u8 *p, RtreeCoord *pCoord){
  assert( ((((char*)p) - (char*)0)&3)==0 );  /* p is always 4-byte aligned */
#if SQLITE_BYTEORDER==1234 && MSVC_VERSION>=1300
  pCoord->u = _byteswap_ulong(*(u32*)p);
#elif SQLITE_BYTEORDER==1234 && (GCC_VERSION>=4003000 || CLANG_VERSION>=3000000)
  pCoord->u = __builtin_bswap32(*(u32*)p);



#elif SQLITE_BYTEORDER==4321
  pCoord->u = *(u32*)p;
#else
  pCoord->u = (
    (((u32)p[0]) << 24) + 
    (((u32)p[1]) << 16) + 
    (((u32)p[2]) <<  8) + 

}

/*
** Functions to serialize a 16 bit integer, 32 bit real number and
** 64 bit integer. The value returned is the number of bytes written
** to the argument buffer (always 2, 4 and 8 respectively).
*/
static void writeInt16(u8 *p, int i){
  p[0] = (i>> 8)&0xFF;
  p[1] = (i>> 0)&0xFF;

}
static int writeCoord(u8 *p, RtreeCoord *pCoord){
  u32 i;
  assert( ((((char*)p) - (char*)0)&3)==0 );  /* p is always 4-byte aligned */
  assert( sizeof(RtreeCoord)==4 );
  assert( sizeof(u32)==4 );
#if SQLITE_BYTEORDER==1234 && (GCC_VERSION>=4003000 || CLANG_VERSION>=3000000)

/*
** get2byteAligned(), unlike get2byte(), requires that its argument point to a
** two-byte aligned address.  get2bytea() is only used for accessing the
** cell addresses in a btree header.
*/
#if SQLITE_BYTEORDER==4321
# define get2byteAligned(x)  (*(u16*)(x))
#elif SQLITE_BYTEORDER==1234 && GCC_VERSION>=4008000

# define get2byteAligned(x)  __builtin_bswap16(*(u16*)(x))
#elif SQLITE_BYTEORDER==1234 && MSVC_VERSION>=1300

# define get2byteAligned(x)  _byteswap_ushort(*(u16*)(x))
#else
# define get2byteAligned(x)  ((x)[0]<<8 | (x)[1])
#endif

          pExpr->op==TK_NE || pExpr->op==TK_IS || pExpr->op==TK_ISNOT );
  assert( pExpr->pLeft );
  aff = sqlite3ExprAffinity(pExpr->pLeft);
  if( pExpr->pRight ){
    aff = sqlite3CompareAffinity(pExpr->pRight, aff);
  }else if( ExprHasProperty(pExpr, EP_xIsSelect) ){
    aff = sqlite3CompareAffinity(pExpr->x.pSelect->pEList->a[0].pExpr, aff);
  }else if( aff==0 ){
    aff = SQLITE_AFF_BLOB;
  }
  return aff;
}

/*
** pExpr is a comparison expression, eg. '=', '<', IN(...) etc.

*/
static void mallocWithAlarm(int n, void **pp){
  void *p;
  int nFull;
  assert( sqlite3_mutex_held(mem0.mutex) );
  assert( n>0 );

  /* In Firefox (circa 2017-02-08), xRoundup() is remapped to an internal
  ** implementation of malloc_good_size(), which must be called in debug
  ** mode and specifically when the DMD "Dark Matter Detector" is enabled
  ** or else a crash results.  Hence, do not attempt to optimize out the
  ** following xRoundup() call. */
  nFull = sqlite3GlobalConfig.m.xRoundup(n);

  sqlite3StatusHighwater(SQLITE_STATUS_MALLOC_SIZE, n);
  if( mem0.alarmThreshold>0 ){
    sqlite3_int64 nUsed = sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED);
    if( nUsed >= mem0.alarmThreshold - nFull ){
      mem0.nearlyFull = 1;

** compiled without mutexes (SQLITE_THREADSAFE=0).
*/
void sqlite3MemoryBarrier(void){
#if defined(SQLITE_MEMORY_BARRIER)
  SQLITE_MEMORY_BARRIER;
#elif defined(__GNUC__)
  __sync_synchronize();
#elif MSVC_VERSION>=1300

  _ReadWriteBarrier();
#elif defined(MemoryBarrier)
  MemoryBarrier();
#endif
}

/*

# define _LARGE_FILE       1
# ifndef _FILE_OFFSET_BITS
#   define _FILE_OFFSET_BITS 64
# endif
# define _LARGEFILE_SOURCE 1
#endif

/* The GCC_VERSION, CLANG_VERSION, and MSVC_VERSION macros are used to
** conditionally include optimizations for each of these compilers.  A
** value of 0 means that compiler is not being used.  The
** SQLITE_DISABLE_INTRINSIC macro means do not use any compiler-specific
** optimizations, and hence set all compiler macros to 0
*/
#if defined(__GNUC__) && !defined(SQLITE_DISABLE_INTRINSIC)
# define GCC_VERSION (__GNUC__*1000000+__GNUC_MINOR__*1000+__GNUC_PATCHLEVEL__)
#else
# define GCC_VERSION 0
#endif


#if defined(__clang__) && !defined(_WIN32) && !defined(SQLITE_DISABLE_INTRINSIC)
# define CLANG_VERSION \
            (__clang_major__*1000000+__clang_minor__*1000+__clang_patchlevel__)
#else
# define CLANG_VERSION 0
#endif
#if defined(_MSC_VER) && !defined(SQLITE_DISABLE_INTRINSIC)
# define MSVC_VERSION _MSC_VER
#else
# define MSVC_VERSION 0
#endif

/* Needed for various definitions... */
#if defined(__GNUC__) && !defined(_GNU_SOURCE)
# define _GNU_SOURCE
#endif

*/
#if !defined(SQLITE_DISABLE_INTRINSIC)
#  if defined(_MSC_VER) && _MSC_VER>=1400
#    if !defined(_WIN32_WCE)
#      include <intrin.h>
#      pragma intrinsic(_byteswap_ushort)
#      pragma intrinsic(_byteswap_ulong)
#      pragma intrinsic(_byteswap_uint64)
#      pragma intrinsic(_ReadWriteBarrier)
#    else
#      include <cmnintrin.h>
#    endif
#  endif
#endif

/*
** Macros to determine whether the machine is big or little endian,
** and whether or not that determination is run-time or compile-time.
**
** For best performance, an attempt is made to guess at the byte-order
** using C-preprocessor macros.  If that is unsuccessful, or if
** -DSQLITE_BYTEORDER=0 is set, then byte-order is determined
** at run-time.
*/
#ifndef SQLITE_BYTEORDER
# if defined(i386)     || defined(__i386__)   || defined(_M_IX86) ||    \
     defined(__x86_64) || defined(__x86_64__) || defined(_M_X64)  ||    \
     defined(_M_AMD64) || defined(_M_ARM)     || defined(__x86)   ||    \
     defined(__arm__)
#   define SQLITE_BYTEORDER    1234
# elif defined(sparc)    || defined(__ppc__)
#   define SQLITE_BYTEORDER    4321
# else
#   define SQLITE_BYTEORDER 0
# endif
#endif


#if SQLITE_BYTEORDER==4321
# define SQLITE_BIGENDIAN    1
# define SQLITE_LITTLEENDIAN 0
# define SQLITE_UTF16NATIVE  SQLITE_UTF16BE

#elif SQLITE_BYTEORDER==1234
# define SQLITE_BIGENDIAN    0
# define SQLITE_LITTLEENDIAN 1
# define SQLITE_UTF16NATIVE  SQLITE_UTF16LE
#else
# ifdef SQLITE_AMALGAMATION
  const int sqlite3one = 1;
# else
  extern const int sqlite3one;
# endif

# define SQLITE_BIGENDIAN    (*(char *)(&sqlite3one)==0)
# define SQLITE_LITTLEENDIAN (*(char *)(&sqlite3one)==1)
# define SQLITE_UTF16NATIVE  (SQLITE_BIGENDIAN?SQLITE_UTF16BE:SQLITE_UTF16LE)
#endif

/*
** Constants for the largest and smallest possible 64-bit signed integers.

** Read or write a four-byte big-endian integer value.
*/
u32 sqlite3Get4byte(const u8 *p){
#if SQLITE_BYTEORDER==4321
  u32 x;
  memcpy(&x,p,4);
  return x;

#elif SQLITE_BYTEORDER==1234 && (GCC_VERSION>=4003000 || CLANG_VERSION>=3000000)
  u32 x;
  memcpy(&x,p,4);
  return __builtin_bswap32(x);
#elif SQLITE_BYTEORDER==1234 && MSVC_VERSION>=1300

  u32 x;
  memcpy(&x,p,4);
  return _byteswap_ulong(x);
#else
  testcase( p[0]&0x80 );
  return ((unsigned)p[0]<<24) | (p[1]<<16) | (p[2]<<8) | p[3];
#endif
}
void sqlite3Put4byte(unsigned char *p, u32 v){
#if SQLITE_BYTEORDER==4321
  memcpy(p,&v,4);

#elif SQLITE_BYTEORDER==1234 && (GCC_VERSION>=4003000 || CLANG_VERSION>=3000000)
  u32 x = __builtin_bswap32(v);
  memcpy(p,&x,4);
#elif SQLITE_BYTEORDER==1234 && MSVC_VERSION>=1300

  u32 x = _byteswap_ulong(v);
  memcpy(p,&x,4);
#else
  p[0] = (u8)(v>>24);
  p[1] = (u8)(v>>16);
  p[2] = (u8)(v>>8);
  p[3] = (u8)v;

/*
** Attempt to add, substract, or multiply the 64-bit signed value iB against
** the other 64-bit signed integer at *pA and store the result in *pA.
** Return 0 on success.  Or if the operation would have resulted in an
** overflow, leave *pA unchanged and return 1.
*/
int sqlite3AddInt64(i64 *pA, i64 iB){

#if GCC_VERSION>=5004000 || CLANG_VERSION>=4000000
  return __builtin_add_overflow(*pA, iB, pA);
#else
  i64 iA = *pA;
  testcase( iA==0 ); testcase( iA==1 );
  testcase( iB==-1 ); testcase( iB==0 );
  if( iB>=0 ){
    testcase( iA>0 && LARGEST_INT64 - iA == iB );
    testcase( iA>0 && LARGEST_INT64 - iA == iB - 1 );
    if( iA>0 && LARGEST_INT64 - iA < iB ) return 1;
  }else{
    testcase( iA<0 && -(iA + LARGEST_INT64) == iB + 1 );
    testcase( iA<0 && -(iA + LARGEST_INT64) == iB + 2 );
    if( iA<0 && -(iA + LARGEST_INT64) > iB + 1 ) return 1;
  }
  *pA += iB;
  return 0; 
#endif
}
int sqlite3SubInt64(i64 *pA, i64 iB){

#if GCC_VERSION>=5004000 || CLANG_VERSION>=4000000
  return __builtin_sub_overflow(*pA, iB, pA);
#else
  testcase( iB==SMALLEST_INT64+1 );
  if( iB==SMALLEST_INT64 ){
    testcase( (*pA)==(-1) ); testcase( (*pA)==0 );
    if( (*pA)>=0 ) return 1;
    *pA -= iB;
    return 0;
  }else{
    return sqlite3AddInt64(pA, -iB);
  }
#endif
}
int sqlite3MulInt64(i64 *pA, i64 iB){

#if GCC_VERSION>=5004000 || CLANG_VERSION>=4000000
  return __builtin_mul_overflow(*pA, iB, pA);
#else
  i64 iA = *pA;
  if( iB>0 ){
    if( iA>LARGEST_INT64/iB ) return 1;
    if( iA<SMALLEST_INT64/iB ) return 1;
  }else if( iB<0 ){

  pScan->idxaff = 0;
  pScan->zCollName = 0;
  if( pIdx ){
    int j = iColumn;
    iColumn = pIdx->aiColumn[j];
    if( iColumn==XN_EXPR ){
      pScan->pIdxExpr = pIdx->aColExpr->a[j].pExpr;
      pScan->zCollName = pIdx->azColl[j];
    }else if( iColumn==pIdx->pTable->iPKey ){
      iColumn = XN_ROWID;
    }else if( iColumn>=0 ){
      pScan->idxaff = pIdx->pTable->aCol[iColumn].affinity;
      pScan->zCollName = pIdx->azColl[j];
    }
  }else if( iColumn==XN_EXPR ){

  CREATE INDEX t10_abcd ON t10(a+b,c+d);
}
do_execsql_test indexexpr1-1200.4 {
  SELECT a+b, c+d FROM t10 ORDER BY a+b, c+d;
} {
  0 0 0 2 0 4 2 0 2 2 4 0
}

# Ticket https://www.sqlite.org/src/tktview/eb703ba7b50c1a
# Incorrect result using an index on an expression with a collating function
#
do_execsql_test indexexpr1-1300.1 {
  CREATE TABLE t1300(a INTEGER PRIMARY KEY, b);
  INSERT INTO t1300 VALUES(1,'coffee'),(2,'COFFEE'),(3,'stress'),(4,'STRESS');
  CREATE INDEX t1300bexpr ON t1300( substr(b,4) );
  SELECT a FROM t1300 WHERE substr(b,4)='ess' COLLATE nocase ORDER BY +a;
} {3 4}

finish_test