int argc,                       /* Number of elements in argv array */
  const char * const *argv,       /* xCreate/xConnect argument array */
  sqlite3_vtab **ppVTab,          /* Write the resulting vtab structure here */
  char **pzErr                    /* Write any error message here */
){
  Fts5Global *pGlobal = (Fts5Global*)pAux;
  const char **azConfig = (const char**)argv;
  int rc;                         /* Return code */
  Fts5Config *pConfig;            /* Results of parsing argc/argv */
  Fts5Table *pTab = 0;            /* New virtual table object */

  /* Parse the arguments */


  rc = sqlite3Fts5ConfigParse(pGlobal, db, argc, azConfig, &pConfig, pzErr);
  assert( (rc==SQLITE_OK && *pzErr==0) || pConfig==0 );

  /* Allocate the new vtab object */
  if( rc==SQLITE_OK ){
    pTab = (Fts5Table*)sqlite3_malloc(sizeof(Fts5Table));
    if( pTab==0 ){
      rc = SQLITE_NOMEM;
    }else{
      memset(pTab, 0, sizeof(Fts5Table));
      pTab->pConfig = pConfig;
      pTab->pGlobal = pGlobal;
    }
  }

  /* Open the index sub-system */
  if( rc==SQLITE_OK ){
    rc = sqlite3Fts5IndexOpen(pConfig, bCreate, &pTab->pIndex, pzErr);
  }

  int argc,                       /* Number of elements in argv array */
  const char * const *argv,       /* xCreate/xConnect argument array */
  sqlite3_vtab **ppVTab,          /* Write the resulting vtab structure here */
  char **pzErr                    /* Write any error message here */
){
  Fts5Global *pGlobal = (Fts5Global*)pAux;
  const char **azConfig = (const char**)argv;
  int rc = SQLITE_OK;             /* Return code */
  Fts5Config *pConfig;            /* Results of parsing argc/argv */
  Fts5Table *pTab = 0;            /* New virtual table object */

  /* Allocate the new vtab object and parse the configuration */
  pTab = (Fts5Table*)sqlite3Fts5MallocZero(&rc, sizeof(Fts5Table));
  if( rc==SQLITE_OK ){
    rc = sqlite3Fts5ConfigParse(pGlobal, db, argc, azConfig, &pConfig, pzErr);
    assert( (rc==SQLITE_OK && *pzErr==0) || pConfig==0 );
  }

  if( rc==SQLITE_OK ){





    pTab->pConfig = pConfig;
    pTab->pGlobal = pGlobal;

  }

  /* Open the index sub-system */
  if( rc==SQLITE_OK ){
    rc = sqlite3Fts5IndexOpen(pConfig, bCreate, &pTab->pIndex, pzErr);
  }

int sqlite3Fts5PoslistNext64(
  const u8 *a, int n,             /* Buffer containing poslist */
  int *pi,                        /* IN/OUT: Offset within a[] */
  i64 *piOff                      /* IN/OUT: Current offset */
);




/*
** End of interface to code in fts5_buffer.c.
**************************************************************************/

/**************************************************************************
** Interface to code in fts5_index.c. fts5_index.c contains contains code
** to access the data stored in the %_data table.
................................................................................
** }
*/

/*
** Open a new iterator to iterate though all docids that match the 
** specified token or token prefix.
*/
Fts5IndexIter *sqlite3Fts5IndexQuery(
  Fts5Index *p,                   /* FTS index to query */
  const char *pToken, int nToken, /* Token (or prefix) to query for */
  int flags                       /* Mask of FTS5INDEX_QUERY_X flags */

);

/*
** Docid list iteration.
*/
int  sqlite3Fts5IterEof(Fts5IndexIter*);
void sqlite3Fts5IterNext(Fts5IndexIter*);
void sqlite3Fts5IterNextFrom(Fts5IndexIter*, i64 iMatch);
i64  sqlite3Fts5IterRowid(Fts5IndexIter*);

/*
** Obtain the position list that corresponds to the current position.
*/
const u8 *sqlite3Fts5IterPoslist(Fts5IndexIter*, int *pn);

/*
** Close an iterator opened by sqlite3Fts5IndexQuery().
*/
void sqlite3Fts5IterClose(Fts5IndexIter*);

/*
................................................................................
** times.
**
** For an insert, it must be called once for each token in the new document.
** If the operation is a delete, it must be called (at least) once for each
** unique token in the document with an iCol value less than zero. The iPos
** argument is ignored for a delete.
*/
void sqlite3Fts5IndexWrite(
  Fts5Index *p,                   /* Index to write to */
  int iCol,                       /* Column token appears in (-ve -> delete) */
  int iPos,                       /* Position of token within column */
  const char *pToken, int nToken  /* Token to add or remove to or from index */
);

/*
** Indicate that subsequent calls to sqlite3Fts5IndexWrite() pertain to
** document iDocid.
*/
void sqlite3Fts5IndexBeginWrite(
  Fts5Index *p,                   /* Index to write to */
  i64 iDocid                      /* Docid to add or remove data from */
);

/*
** Flush any data stored in the in-memory hash tables to the database.
** If the bCommit flag is true, also close any open blob handles.
................................................................................

/*
** Return the total number of entries read from the %_data table by 
** this connection since it was created.
*/
int sqlite3Fts5IndexReads(Fts5Index *p);

/* Malloc utility */
void *sqlite3Fts5MallocZero(int *pRc, int nByte);

/*
** End of interface to code in fts5_index.c.
**************************************************************************/

/**************************************************************************
** Interface to code in fts5_hash.c. 
*/

int sqlite3Fts5PoslistNext64(
  const u8 *a, int n,             /* Buffer containing poslist */
  int *pi,                        /* IN/OUT: Offset within a[] */
  i64 *piOff                      /* IN/OUT: Current offset */
);

/* Malloc utility */
void *sqlite3Fts5MallocZero(int *pRc, int nByte);

/*
** End of interface to code in fts5_buffer.c.
**************************************************************************/

/**************************************************************************
** Interface to code in fts5_index.c. fts5_index.c contains contains code
** to access the data stored in the %_data table.
................................................................................
** }
*/

/*
** Open a new iterator to iterate though all docids that match the 
** specified token or token prefix.
*/
int sqlite3Fts5IndexQuery(
  Fts5Index *p,                   /* FTS index to query */
  const char *pToken, int nToken, /* Token (or prefix) to query for */
  int flags,                      /* Mask of FTS5INDEX_QUERY_X flags */
  Fts5IndexIter **ppIter
);

/*
** Docid list iteration.
*/
int sqlite3Fts5IterEof(Fts5IndexIter*);
int sqlite3Fts5IterNext(Fts5IndexIter*);
int sqlite3Fts5IterNextFrom(Fts5IndexIter*, i64 iMatch);
i64 sqlite3Fts5IterRowid(Fts5IndexIter*);

/*
** Obtain the position list that corresponds to the current position.
*/
int sqlite3Fts5IterPoslist(Fts5IndexIter*, const u8 **pp, int *pn);

/*
** Close an iterator opened by sqlite3Fts5IndexQuery().
*/
void sqlite3Fts5IterClose(Fts5IndexIter*);

/*
................................................................................
** times.
**
** For an insert, it must be called once for each token in the new document.
** If the operation is a delete, it must be called (at least) once for each
** unique token in the document with an iCol value less than zero. The iPos
** argument is ignored for a delete.
*/
int sqlite3Fts5IndexWrite(
  Fts5Index *p,                   /* Index to write to */
  int iCol,                       /* Column token appears in (-ve -> delete) */
  int iPos,                       /* Position of token within column */
  const char *pToken, int nToken  /* Token to add or remove to or from index */
);

/*
** Indicate that subsequent calls to sqlite3Fts5IndexWrite() pertain to
** document iDocid.
*/
int sqlite3Fts5IndexBeginWrite(
  Fts5Index *p,                   /* Index to write to */
  i64 iDocid                      /* Docid to add or remove data from */
);

/*
** Flush any data stored in the in-memory hash tables to the database.
** If the bCommit flag is true, also close any open blob handles.
................................................................................

/*
** Return the total number of entries read from the %_data table by 
** this connection since it was created.
*/
int sqlite3Fts5IndexReads(Fts5Index *p);




/*
** End of interface to code in fts5_index.c.
**************************************************************************/

/**************************************************************************
** Interface to code in fts5_hash.c. 
*/

    *pOut++ = z[i];
  }
  if( bParen ) *pOut++ = '}';

  pBuf->n = pOut - pBuf->p;
  *pOut = '\0';
}

    *pOut++ = z[i];
  }
  if( bParen ) *pOut++ = '}';

  pBuf->n = pOut - pBuf->p;
  *pOut = '\0';
}

void *sqlite3Fts5MallocZero(int *pRc, int nByte){
  void *pRet = 0;
  if( *pRc==SQLITE_OK ){
    pRet = sqlite3_malloc(nByte);
    if( pRet==0 && nByte>0 ){
      *pRc = SQLITE_NOMEM;
    }else{
      memset(pRet, 0, nByte);
    }
  }
  return pRet;
}

/*
** Duplicate the string passed as the only argument into a buffer allocated
** by sqlite3_malloc().
**
** Return 0 if an OOM error is encountered.
*/
static char *fts5Strdup(const char *z){


  return sqlite3_mprintf("%s", z);



}

/*
** Allocate an instance of the default tokenizer ("simple") at 
** Fts5Config.pTokenizer. Return SQLITE_OK if successful, or an SQLite error
** code if an error occurs.
*/
................................................................................

  *ppOut = pRet = (Fts5Config*)sqlite3_malloc(sizeof(Fts5Config));
  if( pRet==0 ) return SQLITE_NOMEM;
  memset(pRet, 0, sizeof(Fts5Config));
  pRet->db = db;
  pRet->iCookie = -1;

  pRet->azCol = (char**)sqlite3_malloc(sizeof(char*) * nArg);
  pRet->zDb = fts5Strdup(azArg[1]);
  pRet->zName = fts5Strdup(azArg[2]);

  if( sqlite3_stricmp(pRet->zName, FTS5_RANK_NAME)==0 ){
    *pzErr = sqlite3_mprintf("reserved fts5 table name: %s", pRet->zName);
    rc = SQLITE_ERROR;
  }else if( pRet->azCol==0 || pRet->zDb==0 || pRet->zName==0 ){
    rc = SQLITE_NOMEM;
  }else{
    int i;
    for(i=3; rc==SQLITE_OK && i<nArg; i++){
      char *zDup = fts5Strdup(azArg[i]);
      if( zDup==0 ){
        rc = SQLITE_NOMEM;
      }else{

        /* Check if this is a special directive - "cmd=arg" */
        if( zDup[0]!='"' && zDup[0]!='\'' && zDup[0]!='[' && zDup[0]!='`' ){
          char *p = zDup;
          while( *p && *p!='=' ) p++;
          if( *p ){
            char *zArg = &p[1];
            *p = '\0';
            sqlite3Fts5Dequote(zArg);
            rc = fts5ConfigParseSpecial(pRet, zDup, zArg, pzErr);
            sqlite3_free(zDup);
            zDup = 0;
          }
        }

        /* If it is not a special directive, it must be a column name. In
        ** this case, check that it is not the reserved column name "rank". */
        if( zDup ){
          sqlite3Fts5Dequote(zDup);
          pRet->azCol[pRet->nCol++] = zDup;
          if( sqlite3_stricmp(zDup, FTS5_RANK_NAME)==0 ){
            *pzErr = sqlite3_mprintf("reserved fts5 column name: %s", zDup);
            rc = SQLITE_ERROR;

          }
        }
      }
    }
  }

  if( rc==SQLITE_OK && pRet->pTok==0 ){

/*
** Duplicate the string passed as the only argument into a buffer allocated
** by sqlite3_malloc().
**
** Return 0 if an OOM error is encountered.
*/
static char *fts5Strdup(int *pRc, const char *z){
  char *pRet = 0;
  if( *pRc==SQLITE_OK ){
    pRet = sqlite3_mprintf("%s", z);
    if( pRet==0 ) *pRc = SQLITE_NOMEM;
  }
  return pRet;
}

/*
** Allocate an instance of the default tokenizer ("simple") at 
** Fts5Config.pTokenizer. Return SQLITE_OK if successful, or an SQLite error
** code if an error occurs.
*/
................................................................................

  *ppOut = pRet = (Fts5Config*)sqlite3_malloc(sizeof(Fts5Config));
  if( pRet==0 ) return SQLITE_NOMEM;
  memset(pRet, 0, sizeof(Fts5Config));
  pRet->db = db;
  pRet->iCookie = -1;

  pRet->azCol = (char**)sqlite3Fts5MallocZero(&rc, sizeof(char*) * nArg);
  pRet->zDb = fts5Strdup(&rc, azArg[1]);
  pRet->zName = fts5Strdup(&rc, azArg[2]);
  if( rc==SQLITE_OK ){
    if( sqlite3_stricmp(pRet->zName, FTS5_RANK_NAME)==0 ){
      *pzErr = sqlite3_mprintf("reserved fts5 table name: %s", pRet->zName);
      rc = SQLITE_ERROR;


    }else{
      int i;
      for(i=3; rc==SQLITE_OK && i<nArg; i++){
        char *zDup = fts5Strdup(&rc, azArg[i]);
        if( zDup ){



          /* Check if this is a special directive - "cmd=arg" */
          if( zDup[0]!='"' && zDup[0]!='\'' && zDup[0]!='[' && zDup[0]!='`' ){
            char *p = zDup;
            while( *p && *p!='=' ) p++;
            if( *p ){
              char *zArg = &p[1];
              *p = '\0';
              sqlite3Fts5Dequote(zArg);
              rc = fts5ConfigParseSpecial(pRet, zDup, zArg, pzErr);
              sqlite3_free(zDup);
              zDup = 0;
            }
          }

          /* If it is not a special directive, it must be a column name. In
           ** this case, check that it is not the reserved column name "rank". */
          if( zDup ){
            sqlite3Fts5Dequote(zDup);
            pRet->azCol[pRet->nCol++] = zDup;
            if( sqlite3_stricmp(zDup, FTS5_RANK_NAME)==0 ){
              *pzErr = sqlite3_mprintf("reserved fts5 column name: %s", zDup);
              rc = SQLITE_ERROR;
            }
          }
        }
      }
    }
  }

  if( rc==SQLITE_OK && pRet->pTok==0 ){

    aIter = (Fts5PoslistReader*)sqlite3_malloc(nByte);
    if( !aIter ) return SQLITE_NOMEM;
  }

  /* Initialize a term iterator for each term in the phrase */
  for(i=0; i<pPhrase->nTerm; i++){
    int n;

    const u8 *a = sqlite3Fts5IterPoslist(pPhrase->aTerm[i].pIter, &n);
    if( sqlite3Fts5PoslistReaderInit(iCol, a, n, &aIter[i]) ) goto ismatch_out;


  }

  while( 1 ){
    int bMatch;
    i64 iPos = aIter[0].iPos;
    do {
      bMatch = 1;
................................................................................
** set output variable *pbEof to true before returning.
*/
static int fts5ExprNearAdvanceAll(
  Fts5Expr *pExpr,                /* Expression pPhrase belongs to */
  Fts5ExprNearset *pNear,         /* Near object to advance iterators of */
  int *pbEof                      /* OUT: Set to true if phrase at EOF */
){
  int rc = SQLITE_OK;             /* Return code */
  int i, j;                       /* Phrase and token index, respectively */

  for(i=0; i<pNear->nPhrase; i++){
    Fts5ExprPhrase *pPhrase = pNear->apPhrase[i];
    for(j=0; j<pPhrase->nTerm; j++){
      Fts5IndexIter *pIter = pPhrase->aTerm[j].pIter;
      sqlite3Fts5IterNext(pIter);
      if( sqlite3Fts5IterEof(pIter) ){
        *pbEof = 1;
        return rc;
      }
    }
  }

  return rc;
}

/*
** Advance iterator pIter until it points to a value equal to or smaller
** than the initial value of *piMin. If this means the iterator points
** to a value smaller than *piMin, update *piMin to the new smallest value.
**
................................................................................
  while( 1 ){
    int i;

    /* Advance the iterators until they all point to the same rowid */
    rc = fts5ExprNearNextRowidMatch(pExpr, pNode, bFromValid, iFrom);
    if( pNode->bEof || rc!=SQLITE_OK ) break;

    for(i=0; i<pNear->nPhrase; i++){
      Fts5ExprPhrase *pPhrase = pNear->apPhrase[i];
      if( pPhrase->nTerm>1 || pNear->iCol>=0 ){
        int bMatch = 0;
        rc = fts5ExprPhraseIsMatch(pExpr, pNear->iCol, pPhrase, &bMatch);
        if( rc!=SQLITE_OK ) return rc;
        if( bMatch==0 ) break;
      }else{
        int n;

        const u8 *a = sqlite3Fts5IterPoslist(pPhrase->aTerm[0].pIter, &n);
        fts5BufferSet(&rc, &pPhrase->poslist, n, a);
      }
    }

    if( i==pNear->nPhrase ){
      int bMatch = 1;
      if( pNear->nPhrase>1 ){
        rc = fts5ExprNearIsMatch(pNear, &bMatch);
      }
      if( rc!=SQLITE_OK || bMatch ) break;
    }

    /* If control flows to here, then the current rowid is not a match.
    ** Advance all term iterators in all phrases to the next rowid. */

    rc = fts5ExprNearAdvanceAll(pExpr, pNear, &pNode->bEof);

    if( pNode->bEof || rc!=SQLITE_OK ) break;
  }

  return rc;
}

/*
................................................................................
  Fts5Expr *pExpr,
  Fts5ExprNode *pNode
){
  Fts5ExprNearset *pNear = pNode->pNear;
  Fts5ExprTerm *pTerm;
  Fts5ExprPhrase *pPhrase;
  int i, j;


  for(i=0; i<pNear->nPhrase; i++){
    pPhrase = pNear->apPhrase[i];
    for(j=0; j<pPhrase->nTerm; j++){
      pTerm = &pPhrase->aTerm[j];
      pTerm->pIter = sqlite3Fts5IndexQuery(
          pExpr->pIndex, pTerm->zTerm, strlen(pTerm->zTerm),
          (pTerm->bPrefix ? FTS5INDEX_QUERY_PREFIX : 0) |
          (pExpr->bAsc ? FTS5INDEX_QUERY_ASC : 0)

      );
      if( pTerm->pIter && sqlite3Fts5IterEof(pTerm->pIter) ){
        pNode->bEof = 1;
        return SQLITE_OK;
      }
    }
  }

  return SQLITE_OK;
}

/* fts5ExprNodeNext() calls fts5ExprNodeNextMatch(). And vice-versa. */
static int fts5ExprNodeNextMatch(Fts5Expr*, Fts5ExprNode*, int, i64);

/*
** Compare the values currently indicated by the two nodes as follows:

    aIter = (Fts5PoslistReader*)sqlite3_malloc(nByte);
    if( !aIter ) return SQLITE_NOMEM;
  }

  /* Initialize a term iterator for each term in the phrase */
  for(i=0; i<pPhrase->nTerm; i++){
    int n;
    const u8 *a;
    rc = sqlite3Fts5IterPoslist(pPhrase->aTerm[i].pIter, &a, &n);
    if( rc || sqlite3Fts5PoslistReaderInit(iCol, a, n, &aIter[i]) ){
      goto ismatch_out;
    }
  }

  while( 1 ){
    int bMatch;
    i64 iPos = aIter[0].iPos;
    do {
      bMatch = 1;
................................................................................
** set output variable *pbEof to true before returning.
*/
static int fts5ExprNearAdvanceAll(
  Fts5Expr *pExpr,                /* Expression pPhrase belongs to */
  Fts5ExprNearset *pNear,         /* Near object to advance iterators of */
  int *pbEof                      /* OUT: Set to true if phrase at EOF */
){

  int i, j;                       /* Phrase and token index, respectively */

  for(i=0; i<pNear->nPhrase; i++){
    Fts5ExprPhrase *pPhrase = pNear->apPhrase[i];
    for(j=0; j<pPhrase->nTerm; j++){
      Fts5IndexIter *pIter = pPhrase->aTerm[j].pIter;
      int rc = sqlite3Fts5IterNext(pIter);
      if( rc || sqlite3Fts5IterEof(pIter) ){
        *pbEof = 1;
        return rc;
      }
    }
  }

  return SQLITE_OK;
}

/*
** Advance iterator pIter until it points to a value equal to or smaller
** than the initial value of *piMin. If this means the iterator points
** to a value smaller than *piMin, update *piMin to the new smallest value.
**
................................................................................
  while( 1 ){
    int i;

    /* Advance the iterators until they all point to the same rowid */
    rc = fts5ExprNearNextRowidMatch(pExpr, pNode, bFromValid, iFrom);
    if( pNode->bEof || rc!=SQLITE_OK ) break;

    for(i=0; rc==SQLITE_OK && i<pNear->nPhrase; i++){
      Fts5ExprPhrase *pPhrase = pNear->apPhrase[i];
      if( pPhrase->nTerm>1 || pNear->iCol>=0 ){
        int bMatch = 0;
        rc = fts5ExprPhraseIsMatch(pExpr, pNear->iCol, pPhrase, &bMatch);

        if( bMatch==0 ) break;
      }else{
        int n;
        const u8 *a;
        rc = sqlite3Fts5IterPoslist(pPhrase->aTerm[0].pIter, &a, &n);
        fts5BufferSet(&rc, &pPhrase->poslist, n, a);
      }
    }

    if( rc==SQLITE_OK && i==pNear->nPhrase ){
      int bMatch = 1;
      if( pNear->nPhrase>1 ){
        rc = fts5ExprNearIsMatch(pNear, &bMatch);
      }
      if( rc!=SQLITE_OK || bMatch ) break;
    }

    /* If control flows to here, then the current rowid is not a match.
    ** Advance all term iterators in all phrases to the next rowid. */
    if( rc==SQLITE_OK ){
      rc = fts5ExprNearAdvanceAll(pExpr, pNear, &pNode->bEof);
    }
    if( pNode->bEof || rc!=SQLITE_OK ) break;
  }

  return rc;
}

/*
................................................................................
  Fts5Expr *pExpr,
  Fts5ExprNode *pNode
){
  Fts5ExprNearset *pNear = pNode->pNear;
  Fts5ExprTerm *pTerm;
  Fts5ExprPhrase *pPhrase;
  int i, j;
  int rc = SQLITE_OK;

  for(i=0; rc==SQLITE_OK && i<pNear->nPhrase; i++){
    pPhrase = pNear->apPhrase[i];
    for(j=0; j<pPhrase->nTerm; j++){
      pTerm = &pPhrase->aTerm[j];
      rc = sqlite3Fts5IndexQuery(
          pExpr->pIndex, pTerm->zTerm, strlen(pTerm->zTerm),
          (pTerm->bPrefix ? FTS5INDEX_QUERY_PREFIX : 0) |
          (pExpr->bAsc ? FTS5INDEX_QUERY_ASC : 0),
          &pTerm->pIter
      );
      if( pTerm->pIter && sqlite3Fts5IterEof(pTerm->pIter) ){
        pNode->bEof = 1;
        break;
      }
    }
  }

  return rc;
}

/* fts5ExprNodeNext() calls fts5ExprNodeNextMatch(). And vice-versa. */
static int fts5ExprNodeNextMatch(Fts5Expr*, Fts5ExprNode*, int, i64);

/*
** Compare the values currently indicated by the two nodes as follows:

#ifdef SQLITE_DEBUG
static int fts5Corrupt() { return SQLITE_CORRUPT_VTAB; }
# define FTS5_CORRUPT fts5Corrupt()
#else
# define FTS5_CORRUPT SQLITE_CORRUPT_VTAB
#endif

#ifdef SQLITE_DEBUG
static int fts5MissingData() { return 0; }
#else
# define fts5MissingData() 
#endif


typedef struct Fts5BtreeIter Fts5BtreeIter;
typedef struct Fts5BtreeIterLevel Fts5BtreeIterLevel;
typedef struct Fts5ChunkIter Fts5ChunkIter;
typedef struct Fts5Data Fts5Data;
typedef struct Fts5DlidxIter Fts5DlidxIter;
typedef struct Fts5MultiSegIter Fts5MultiSegIter;
................................................................................
  Fts5Buffer term;                /* Current term */
  int iLeaf;                      /* Leaf containing terms >= current term */
  int nEmpty;                     /* Number of "empty" leaves following iLeaf */
  int bEof;                       /* Set to true at EOF */
  int bDlidx;                     /* True if there exists a dlidx */
};


/*
** Decode a segment-data rowid from the %_data table. This function is
** the opposite of macro FTS5_SEGMENT_ROWID().
*/
static void fts5DecodeRowid(
  i64 iRowid,                     /* Rowid from %_data table */
  int *piIdx,                     /* OUT: Index */
  int *piSegid,                   /* OUT: Segment id */
  int *piHeight,                  /* OUT: Height */
  int *piPgno                     /* OUT: Page number */
){
  *piPgno = (int)(iRowid & (((i64)1 << FTS5_DATA_PAGE_B) - 1));
  iRowid >>= FTS5_DATA_PAGE_B;

  *piHeight = (int)(iRowid & (((i64)1 << FTS5_DATA_HEIGHT_B) - 1));
  iRowid >>= FTS5_DATA_HEIGHT_B;

  *piSegid = (int)(iRowid & (((i64)1 << FTS5_DATA_ID_B) - 1));
  iRowid >>= FTS5_DATA_ID_B;

  *piIdx = (int)(iRowid & (((i64)1 << FTS5_DATA_IDX_B) - 1));
}

static void fts5DebugRowid(int *pRc, Fts5Buffer *pBuf, i64 iKey){
  int iIdx,iSegid,iHeight,iPgno;  /* Rowid compenents */
  fts5DecodeRowid(iKey, &iIdx, &iSegid, &iHeight, &iPgno);

  if( iSegid==0 ){
    if( iKey==FTS5_AVERAGES_ROWID ){
      sqlite3Fts5BufferAppendPrintf(pRc, pBuf, "(averages) ");
    }else{
      sqlite3Fts5BufferAppendPrintf(pRc, pBuf, 
          "{structure idx=%d}", (int)(iKey-10)
      );
    }
  }
  else if( iHeight==FTS5_SEGMENT_MAX_HEIGHT ){
    sqlite3Fts5BufferAppendPrintf(pRc, pBuf, "(dlidx idx=%d segid=%d pgno=%d)",
        iIdx, iSegid, iPgno
    );
  }else{
    sqlite3Fts5BufferAppendPrintf(pRc, pBuf, "(idx=%d segid=%d h=%d pgno=%d)",
        iIdx, iSegid, iHeight, iPgno
    );
  }
}

static void fts5DebugStructure(
  int *pRc,                       /* IN/OUT: error code */
  Fts5Buffer *pBuf,
  Fts5Structure *p
){
  int iLvl, iSeg;                 /* Iterate through levels, segments */

  for(iLvl=0; iLvl<p->nLevel; iLvl++){
    Fts5StructureLevel *pLvl = &p->aLevel[iLvl];
    sqlite3Fts5BufferAppendPrintf(pRc, pBuf, 
        " {lvl=%d nMerge=%d", iLvl, pLvl->nMerge
    );
    for(iSeg=0; iSeg<pLvl->nSeg; iSeg++){
      Fts5StructureSegment *pSeg = &pLvl->aSeg[iSeg];
      sqlite3Fts5BufferAppendPrintf(pRc, pBuf, 
          " {id=%d h=%d leaves=%d..%d}", pSeg->iSegid, pSeg->nHeight, 
          pSeg->pgnoFirst, pSeg->pgnoLast
      );
    }
    sqlite3Fts5BufferAppendPrintf(pRc, pBuf, "}");
  }
}



static void fts5PutU16(u8 *aOut, u16 iVal){
  aOut[0] = (iVal>>8);
  aOut[1] = (iVal&0xFF);
}

static u16 fts5GetU16(const u8 *aIn){
................................................................................
  assert( p->rc==SQLITE_OK );
  pRet = sqlite3_malloc(nByte);
  if( pRet==0 ){
    p->rc = SQLITE_NOMEM;
  }else{
    memset(pRet, 0, nByte);
  }
  return pRet;
}

void *sqlite3Fts5MallocZero(int *pRc, int nByte){
  void *pRet = 0;
  if( *pRc==SQLITE_OK ){
    pRet = sqlite3_malloc(nByte);
    if( pRet==0 && nByte>0 ){
      *pRc = SQLITE_NOMEM;
    }else{
      memset(pRet, 0, nByte);
    }
  }
  return pRet;
}

/*
** Compare the contents of the pLeft buffer with the pRight/nRight blob.
**
** Return -ve if pLeft is smaller than pRight, 0 if they are equal or
................................................................................
    if( p->pReader==0 ){
      Fts5Config *pConfig = p->pConfig;
      rc = sqlite3_blob_open(pConfig->db, 
          pConfig->zDb, p->zDataTbl, "block", iRowid, 0, &p->pReader
      );
    }

    if( rc ) fts5MissingData();

    if( rc==SQLITE_OK ){
      int nByte = sqlite3_blob_bytes(p->pReader);
      if( pBuf ){
        fts5BufferZero(pBuf);
        fts5BufferGrow(&rc, pBuf, nByte);
        rc = sqlite3_blob_read(p->pReader, pBuf->p, nByte, 0);
        if( rc==SQLITE_OK ) pBuf->n = nByte;
................................................................................
  if( p->rc==SQLITE_OK ){
    p->rc = sqlite3Fts5HashWrite(
        p->apHash[iIdx], p->iWriteRowid, iCol, iPos, pToken, nToken
    );
  }
}

/*
** Insert or remove data to or from the index. Each time a document is 
** added to or removed from the index, this function is called one or more
** times.
**
** For an insert, it must be called once for each token in the new document.
** If the operation is a delete, it must be called (at least) once for each
** unique token in the document with an iCol value less than zero. The iPos
** argument is ignored for a delete.
*/
void sqlite3Fts5IndexWrite(
  Fts5Index *p,                   /* Index to write to */
  int iCol,                       /* Column token appears in (-ve -> delete) */
  int iPos,                       /* Position of token within column */
  const char *pToken, int nToken  /* Token to add or remove to or from index */
){
  int i;                          /* Used to iterate through indexes */
  Fts5Config *pConfig = p->pConfig;

  /* If an error has already occured this call is a no-op. */
  if( p->rc!=SQLITE_OK ) return;

  /* Allocate hash tables if they have not already been allocated */
  if( p->apHash==0 ){
    int nHash = pConfig->nPrefix + 1;
    p->apHash = (Fts5Hash**)fts5IdxMalloc(p, sizeof(Fts5Hash*) * nHash);
    for(i=0; p->rc==SQLITE_OK && i<nHash; i++){
      p->rc = sqlite3Fts5HashNew(&p->apHash[i], &p->nPendingData);
    }
  }

  /* Add the new token to the main terms hash table. And to each of the
  ** prefix hash tables that it is large enough for. */
  fts5AddTermToHash(p, 0, iCol, iPos, pToken, nToken);
  for(i=0; i<pConfig->nPrefix; i++){
    if( nToken>=pConfig->aPrefix[i] ){
      fts5AddTermToHash(p, i+1, iCol, iPos, pToken, pConfig->aPrefix[i]);
    }
  }
}

/*
** Allocate a new segment-id for the structure pStruct.
**
** If an error has already occurred, this function is a no-op. 0 is 
** returned in this case.
*/
static int fts5AllocateSegid(Fts5Index *p, Fts5Structure *pStruct){
................................................................................
  /* Flush the terms and each prefix index to disk */
  for(i=0; i<=pConfig->nPrefix; i++){
    fts5FlushOneHash(p, i, &nLeaf);
  }
  p->nPendingData = 0;
}

/*
** Indicate that all subsequent calls to sqlite3Fts5IndexWrite() pertain
** to the document with rowid iRowid.
*/
void sqlite3Fts5IndexBeginWrite(Fts5Index *p, i64 iRowid){
  if( iRowid<=p->iWriteRowid || (p->nPendingData > p->nMaxPendingData) ){
    fts5IndexFlush(p);
  }
  p->iWriteRowid = iRowid;
}

/*
** Commit data to disk.
*/
int sqlite3Fts5IndexSync(Fts5Index *p, int bCommit){
  fts5IndexFlush(p);
  if( bCommit ) fts5CloseReader(p);
  return p->rc;
}

/*
** Discard any data stored in the in-memory hash tables. Do not write it
** to the database. Additionally, assume that the contents of the %_data
** table may have changed on disk. So any in-memory caches of %_data 
** records must be invalidated.
*/
int sqlite3Fts5IndexRollback(Fts5Index *p){
  fts5CloseReader(p);
  fts5IndexDiscardData(p);
  return SQLITE_OK;
}

/*
** Open a new Fts5Index handle. If the bCreate argument is true, create
** and initialize the underlying %_data table.
**
** If successful, set *pp to point to the new object and return SQLITE_OK.
** Otherwise, set *pp to NULL and return an SQLite error code.
*/
int sqlite3Fts5IndexOpen(
  Fts5Config *pConfig, 
  int bCreate, 
  Fts5Index **pp,
  char **pzErr
){
  int rc = SQLITE_OK;
  Fts5Index *p;                   /* New object */

  *pp = p = (Fts5Index*)sqlite3_malloc(sizeof(Fts5Index));
  if( !p ) return SQLITE_NOMEM;

  memset(p, 0, sizeof(Fts5Index));
  p->pConfig = pConfig;
  p->nCrisisMerge = FTS5_CRISIS_MERGE;
  p->nWorkUnit = FTS5_WORK_UNIT;
  p->nMaxPendingData = 1024*1024;
  p->zDataTbl = sqlite3_mprintf("%s_data", pConfig->zName);
  if( p->zDataTbl==0 ){
    rc = SQLITE_NOMEM;
  }else if( bCreate ){
    int i;
    Fts5Structure s;
    rc = sqlite3Fts5CreateTable(
        pConfig, "data", "id INTEGER PRIMARY KEY, block BLOB", 0, pzErr
    );
    if( rc==SQLITE_OK ){
      memset(&s, 0, sizeof(Fts5Structure));
      for(i=0; i<pConfig->nPrefix+1; i++){
        fts5StructureWrite(p, i, &s);
      }
      rc = p->rc;
    }
    sqlite3Fts5IndexSetAverages(p, (const u8*)"", 0);
  }

  if( rc ){
    sqlite3Fts5IndexClose(p, 0);
    *pp = 0;
  }
  return rc;
}

/*
** Close a handle opened by an earlier call to sqlite3Fts5IndexOpen().
*/
int sqlite3Fts5IndexClose(Fts5Index *p, int bDestroy){
  int rc = SQLITE_OK;
  if( bDestroy ){
    rc = sqlite3Fts5DropTable(p->pConfig, "data");
  }
  assert( p->pReader==0 );
  sqlite3_finalize(p->pWriter);
  sqlite3_finalize(p->pDeleter);
  if( p->apHash ){
    int i;
    for(i=0; i<=p->pConfig->nPrefix; i++){
      sqlite3Fts5HashFree(p->apHash[i]);
    }
    sqlite3_free(p->apHash);
  }
  sqlite3_free(p->zDataTbl);
  sqlite3_free(p);
  return rc;
}

/*
** Return a simple checksum value based on the arguments.
*/
static u64 fts5IndexEntryCksum(
  i64 iRowid, 
  int iCol, 
  int iPos, 
................................................................................
  int nTerm
){
  int i;
  u64 ret = iRowid;
  ret += (ret<<3) + iCol;
  ret += (ret<<3) + iPos;
  for(i=0; i<nTerm; i++) ret += (ret<<3) + pTerm[i];
  return ret;
}

/*
** Calculate and return a checksum that is the XOR of the index entry
** checksum of all entries that would be generated by the token specified
** by the final 5 arguments.
*/
u64 sqlite3Fts5IndexCksum(
  Fts5Config *pConfig,            /* Configuration object */
  i64 iRowid,                     /* Document term appears in */
  int iCol,                       /* Column term appears in */
  int iPos,                       /* Position term appears in */
  const char *pTerm, int nTerm    /* Term at iPos */
){
  u64 ret = 0;                    /* Return value */
  int iIdx;                       /* For iterating through indexes */

  for(iIdx=0; iIdx<=pConfig->nPrefix; iIdx++){
    int n = ((iIdx==pConfig->nPrefix) ? nTerm : pConfig->aPrefix[iIdx]);
    if( n<=nTerm ){
      ret ^= fts5IndexEntryCksum(iRowid, iCol, iPos, pTerm, n);
    }
  }

  return ret;
}

static void fts5BtreeIterInit(
  Fts5Index *p, 
  int iIdx,
  Fts5StructureSegment *pSeg, 
................................................................................
  if( p->rc==SQLITE_OK && iter.iLeaf!=pSeg->pgnoLast ){
    p->rc = FTS5_CORRUPT;
  }

  fts5BtreeIterFree(&iter);
}

/*
** Run internal checks to ensure that the FTS index (a) is internally 
** consistent and (b) contains entries for which the XOR of the checksums
** as calculated by fts5IndexEntryCksum() is cksum.
**
** Return SQLITE_CORRUPT if any of the internal checks fail, or if the
** checksum does not match. Return SQLITE_OK if all checks pass without
** error, or some other SQLite error code if another error (e.g. OOM)
** occurs.
*/
int sqlite3Fts5IndexIntegrityCheck(Fts5Index *p, u64 cksum){
  Fts5Config *pConfig = p->pConfig;
  int iIdx;                       /* Used to iterate through indexes */
  int rc;                         /* Return code */
  u64 cksum2 = 0;                 /* Checksum based on contents of indexes */

  /* Check that the checksum of the index matches the argument checksum */
  for(iIdx=0; iIdx<=pConfig->nPrefix; iIdx++){
    Fts5MultiSegIter *pIter;
    Fts5Structure *pStruct = fts5StructureRead(p, iIdx);
    for(fts5MultiIterNew(p, pStruct, iIdx, 0, 0, 0, -1, 0, &pIter);
        fts5MultiIterEof(p, pIter)==0;
        fts5MultiIterNext(p, pIter, 0, 0)
    ){
      Fts5PosIter sPos;           /* Used to iterate through position list */
      int n;                      /* Size of term in bytes */
      i64 iRowid = fts5MultiIterRowid(pIter);
      char *z = (char*)fts5MultiIterTerm(pIter, &n);

      for(fts5PosIterInit(p, pIter, &sPos);
          fts5PosIterEof(p, &sPos)==0;
          fts5PosIterNext(p, &sPos)
      ){
        cksum2 ^= fts5IndexEntryCksum(iRowid, sPos.iCol, sPos.iPos, z, n);
#if 0
        fprintf(stdout, "rowid=%d ", (int)iRowid);
        fprintf(stdout, "term=%.*s ", n, z);
        fprintf(stdout, "col=%d ", sPos.iCol);
        fprintf(stdout, "off=%d\n", sPos.iPos);
        fflush(stdout);
#endif
      }
    }
    fts5MultiIterFree(p, pIter);
    fts5StructureRelease(pStruct);
  }
  rc = p->rc;
  if( rc==SQLITE_OK && cksum!=cksum2 ) rc = FTS5_CORRUPT;

  /* Check that the internal nodes of each segment match the leaves */
  for(iIdx=0; rc==SQLITE_OK && iIdx<=pConfig->nPrefix; iIdx++){
    Fts5Structure *pStruct = fts5StructureRead(p, iIdx);
    if( pStruct ){
      int iLvl, iSeg;
      for(iLvl=0; iLvl<pStruct->nLevel; iLvl++){
        for(iSeg=0; iSeg<pStruct->aLevel[iLvl].nSeg; iSeg++){
          Fts5StructureSegment *pSeg = &pStruct->aLevel[iLvl].aSeg[iSeg];
          fts5IndexIntegrityCheckSegment(p, iIdx, pSeg);
        }
      }
    }
    fts5StructureRelease(pStruct);
    rc = p->rc;
  }

  return rc;
}

/*
** This is part of the fts5_decode() debugging aid.
**
** Arguments pBlob/nBlob contain a serialized Fts5Structure object. This
** function appends a human-readable representation of the same object
** to the buffer passed as the second argument. 
*/
static void fts5DecodeStructure(
  int *pRc,                       /* IN/OUT: error code */
  Fts5Buffer *pBuf,
  const u8 *pBlob, int nBlob
){
  int rc;                         /* Return code */
  Fts5Structure *p = 0;           /* Decoded structure object */

  rc = fts5StructureDecode(pBlob, nBlob, 0, &p);
  if( rc!=SQLITE_OK ){
    *pRc = rc;
    return;
  }

  fts5DebugStructure(pRc, pBuf, p);
  fts5StructureRelease(p);
}

/*
** Buffer (a/n) is assumed to contain a list of serialized varints. Read
** each varint and append its string representation to buffer pBuf. Return
** after either the input buffer is exhausted or a 0 value is read.
**
** The return value is the number of bytes read from the input buffer.
*/
static int fts5DecodePoslist(int *pRc, Fts5Buffer *pBuf, const u8 *a, int n){
  int iOff = 0;
  while( iOff<n ){
    int iVal;
    iOff += getVarint32(&a[iOff], iVal);
    sqlite3Fts5BufferAppendPrintf(pRc, pBuf, " %d", iVal);
  }
  return iOff;
}

/*
** The start of buffer (a/n) contains the start of a doclist. The doclist
** may or may not finish within the buffer. This function appends a text
** representation of the part of the doclist that is present to buffer
** pBuf. 
**
** The return value is the number of bytes read from the input buffer.
*/
static int fts5DecodeDoclist(int *pRc, Fts5Buffer *pBuf, const u8 *a, int n){
  i64 iDocid;
  int iOff = 0;

  if( iOff<n ){
    iOff += sqlite3GetVarint(&a[iOff], (u64*)&iDocid);
    sqlite3Fts5BufferAppendPrintf(pRc, pBuf, " rowid=%lld", iDocid);
  }
  while( iOff<n ){
    int nPos;
    iOff += getVarint32(&a[iOff], nPos);
    iOff += fts5DecodePoslist(pRc, pBuf, &a[iOff], MIN(n-iOff, nPos));
    if( iOff<n ){
      i64 iDelta;
      iOff += sqlite3GetVarint(&a[iOff], (u64*)&iDelta);
      if( iDelta==0 ) return iOff;
      iDocid -= iDelta;
      sqlite3Fts5BufferAppendPrintf(pRc, pBuf, " rowid=%lld", iDocid);
    }
  }

  return iOff;
}

/*
** The implementation of user-defined scalar function fts5_decode().
*/
static void fts5DecodeFunction(
  sqlite3_context *pCtx,          /* Function call context */
  int nArg,                       /* Number of args (always 2) */
  sqlite3_value **apVal           /* Function arguments */
){
  i64 iRowid;                     /* Rowid for record being decoded */
  int iIdx,iSegid,iHeight,iPgno;  /* Rowid components */
  const u8 *a; int n;             /* Record to decode */
  Fts5Buffer s;                   /* Build up text to return here */
  int rc = SQLITE_OK;             /* Return code */

  assert( nArg==2 );
  memset(&s, 0, sizeof(Fts5Buffer));
  iRowid = sqlite3_value_int64(apVal[0]);
  n = sqlite3_value_bytes(apVal[1]);
  a = sqlite3_value_blob(apVal[1]);
  fts5DecodeRowid(iRowid, &iIdx, &iSegid, &iHeight, &iPgno);

  fts5DebugRowid(&rc, &s, iRowid);
  if( iHeight==FTS5_SEGMENT_MAX_HEIGHT ){
    int i = 0;
    i64 iPrev;
    if( n>0 ){
      i = getVarint(&a[i], (u64*)&iPrev);
      sqlite3Fts5BufferAppendPrintf(&rc, &s, " %lld", iPrev);
    }
    while( i<n ){
      i64 iVal;
      i += getVarint(&a[i], (u64*)&iVal);
      if( iVal==0 ){
        sqlite3Fts5BufferAppendPrintf(&rc, &s, " x");
      }else{
        iPrev = iPrev - iVal;
        sqlite3Fts5BufferAppendPrintf(&rc, &s, " %lld", iPrev);
      }
    }

  }else
  if( iSegid==0 ){
    if( iRowid==FTS5_AVERAGES_ROWID ){
      /* todo */
    }else{
      fts5DecodeStructure(&rc, &s, a, n);
    }
  }else{

    Fts5Buffer term;
    memset(&term, 0, sizeof(Fts5Buffer));

    if( iHeight==0 ){
      int iTermOff = 0;
      int iRowidOff = 0;
      int iOff;
      int nKeep = 0;

      iRowidOff = fts5GetU16(&a[0]);
      iTermOff = fts5GetU16(&a[2]);

      if( iRowidOff ){
        iOff = iRowidOff;
      }else if( iTermOff ){
        iOff = iTermOff;
      }else{
        iOff = n;
      }
      fts5DecodePoslist(&rc, &s, &a[4], iOff-4);


      assert( iRowidOff==0 || iOff==iRowidOff );
      if( iRowidOff ){
        iOff += fts5DecodeDoclist(&rc, &s, &a[iOff], n-iOff);
      }

      assert( iTermOff==0 || iOff==iTermOff );
      while( iOff<n ){
        int nByte;
        iOff += getVarint32(&a[iOff], nByte);
        term.n= nKeep;
        fts5BufferAppendBlob(&rc, &term, nByte, &a[iOff]);
        iOff += nByte;

        sqlite3Fts5BufferAppendPrintf(
            &rc, &s, " term=%.*s", term.n, (const char*)term.p
        );
        iOff += fts5DecodeDoclist(&rc, &s, &a[iOff], n-iOff);
        if( iOff<n ){
          iOff += getVarint32(&a[iOff], nKeep);
        }
      }
      fts5BufferFree(&term);
    }else{
      Fts5NodeIter ss;
      for(fts5NodeIterInit(a, n, &ss); ss.aData; fts5NodeIterNext(&rc, &ss)){
        if( ss.term.n==0 ){
          sqlite3Fts5BufferAppendPrintf(&rc, &s, " left=%d", ss.iChild);
        }else{
          sqlite3Fts5BufferAppendPrintf(&rc,&s, " \"%.*s\"", 
              ss.term.n, ss.term.p
          );
        }
        if( ss.nEmpty ){
          sqlite3Fts5BufferAppendPrintf(&rc, &s, " empty=%d%s", ss.nEmpty,
              ss.bDlidx ? "*" : ""
          );
        }
      }
      fts5NodeIterFree(&ss);
    }
  }
  
  if( rc==SQLITE_OK ){
    sqlite3_result_text(pCtx, (const char*)s.p, s.n, SQLITE_TRANSIENT);
  }else{
    sqlite3_result_error_code(pCtx, rc);
  }
  fts5BufferFree(&s);
}

/*
** This is called as part of registering the FTS5 module with database
** connection db. It registers several user-defined scalar functions useful
** with FTS5.
**
** If successful, SQLITE_OK is returned. If an error occurs, some other
** SQLite error code is returned instead.
*/
int sqlite3Fts5IndexInit(sqlite3 *db){
  int rc = sqlite3_create_function(
      db, "fts5_decode", 2, SQLITE_UTF8, 0, fts5DecodeFunction, 0, 0
  );
  return rc;
}

/*
** Iterator pMulti currently points to a valid entry (not EOF). This
** function appends a copy of the position-list of the entry pMulti 
** currently points to to buffer pBuf.
**
** If an error occurs, an error code is left in p->rc. It is assumed
** no error has already occurred when this function is called.
................................................................................
      fts5DoclistIterInit(&doclist, bAsc, pIter->pDoclist);
    }
  }

  fts5StructureRelease(pStruct);
  sqlite3_free(aBuf);
}







/*

























































































































































































































































** Open a new iterator to iterate though all docids that match the 
** specified token or token prefix.
*/
Fts5IndexIter *sqlite3Fts5IndexQuery(
  Fts5Index *p,                   /* FTS index to query */
  const char *pToken, int nToken, /* Token (or prefix) to query for */
  int flags                       /* Mask of FTS5INDEX_QUERY_X flags */

){
  Fts5IndexIter *pRet;
  int iIdx = 0;

  if( flags & FTS5INDEX_QUERY_PREFIX ){
    Fts5Config *pConfig = p->pConfig;
    for(iIdx=1; iIdx<=pConfig->nPrefix; iIdx++){
................................................................................
      if( pConfig->aPrefix[iIdx-1]==nToken ) break;
    }
    if( iIdx>pConfig->nPrefix ){
      iIdx = -1;
    }
  }

  pRet = (Fts5IndexIter*)sqlite3_malloc(sizeof(Fts5IndexIter));
  if( pRet ){
    memset(pRet, 0, sizeof(Fts5IndexIter));

    pRet->pIndex = p;
    if( iIdx>=0 ){
      pRet->pStruct = fts5StructureRead(p, iIdx);
      if( pRet->pStruct ){
................................................................................
    }
  }

  if( p->rc ){
    sqlite3Fts5IterClose(pRet);
    pRet = 0;
  }

  return pRet;
}

/*
** Return true if the iterator passed as the only argument is at EOF.
*/
int sqlite3Fts5IterEof(Fts5IndexIter *pIter){

  if( pIter->pDoclist ){ 
    return pIter->pDoclist->aPoslist==0; 
  }else{
    return fts5MultiIterEof(pIter->pIndex, pIter->pMulti);
  }
}

/*
** Move to the next matching rowid. 
*/
void sqlite3Fts5IterNext(Fts5IndexIter *pIter){

  if( pIter->pDoclist ){
    fts5DoclistIterNext(pIter->pDoclist);
  }else{
    fts5BufferZero(&pIter->poslist);
    fts5MultiIterNext(pIter->pIndex, pIter->pMulti, 0, 0);
  }

}

/*
** Move to the next matching rowid that occurs at or after iMatch. The
** definition of "at or after" depends on whether this iterator iterates
** in ascending or descending rowid order.
*/
void sqlite3Fts5IterNextFrom(Fts5IndexIter *pIter, i64 iMatch){
  if( pIter->pDoclist ){
    assert( 0 );
    /* fts5DoclistIterNextFrom(pIter->pDoclist, iMatch); */
  }else{
    fts5MultiIterNextFrom(pIter->pIndex, pIter->pMulti, iMatch);
  }

}

/*
** Return the current rowid.
*/
i64 sqlite3Fts5IterRowid(Fts5IndexIter *pIter){
  if( pIter->pDoclist ){
................................................................................
** Return a pointer to a buffer containing a copy of the position list for
** the current entry. Output variable *pn is set to the size of the buffer 
** in bytes before returning.
**
** The returned buffer does not include the 0x00 terminator byte stored on
** disk.
*/
const u8 *sqlite3Fts5IterPoslist(Fts5IndexIter *pIter, int *pn){

  if( pIter->pDoclist ){
    *pn = pIter->pDoclist->nPoslist;
    return pIter->pDoclist->aPoslist;
  }else{
    Fts5Index *p = pIter->pIndex;
    fts5BufferZero(&pIter->poslist);
    fts5MultiIterPoslist(p, pIter->pMulti, 0, &pIter->poslist);
    assert( p->rc==SQLITE_OK );
    if( p->rc ) return 0;
    *pn = pIter->poslist.n;
    return pIter->poslist.p;
  }

}

/*
** Close an iterator opened by an earlier call to sqlite3Fts5IndexQuery().
*/
void sqlite3Fts5IterClose(Fts5IndexIter *pIter){
  if( pIter ){
................................................................................

/*
** Read the "averages" record into the buffer supplied as the second 
** argument. Return SQLITE_OK if successful, or an SQLite error code
** if an error occurs.
*/
int sqlite3Fts5IndexGetAverages(Fts5Index *p, Fts5Buffer *pBuf){

  fts5DataReadOrBuffer(p, pBuf, FTS5_AVERAGES_ROWID);
  return p->rc;
}

/*
** Replace the current "averages" record with the contents of the buffer 
** supplied as the second argument.
*/
int sqlite3Fts5IndexSetAverages(Fts5Index *p, const u8 *pData, int nData){

  fts5DataWrite(p, FTS5_AVERAGES_ROWID, pData, nData);
  return p->rc;
}

/*
** Return the total number of blocks this module has read from the %_data
** table since it was created.
*/
int sqlite3Fts5IndexReads(Fts5Index *p){
  return p->nRead;
}

/*
** Set the 32-bit cookie value at the start of all structure records to
** the value passed as the second argument.
**
** Return SQLITE_OK if successful, or an SQLite error code if an error
** occurs.
*/
int sqlite3Fts5IndexSetCookie(Fts5Index *p, int iNew){
  int rc = SQLITE_OK;
  Fts5Config *pConfig = p->pConfig;
  u8 aCookie[4];
  int i;


  sqlite3Fts5Put32(aCookie, iNew);
  for(i=0; rc==SQLITE_OK && i<=pConfig->nPrefix; i++){
    sqlite3_blob *pBlob = 0;
    i64 iRowid = FTS5_STRUCTURE_ROWID(i);
    rc = sqlite3_blob_open(
        pConfig->db, pConfig->zDb, p->zDataTbl, "block", iRowid, 1, &pBlob
    );
................................................................................
      sqlite3_blob_write(pBlob, aCookie, 4, 0);
      rc = sqlite3_blob_close(pBlob);
    }
  }

  return rc;
}

#ifdef SQLITE_DEBUG
static int fts5Corrupt() { return SQLITE_CORRUPT_VTAB; }
# define FTS5_CORRUPT fts5Corrupt()
#else
# define FTS5_CORRUPT SQLITE_CORRUPT_VTAB
#endif








typedef struct Fts5BtreeIter Fts5BtreeIter;
typedef struct Fts5BtreeIterLevel Fts5BtreeIterLevel;
typedef struct Fts5ChunkIter Fts5ChunkIter;
typedef struct Fts5Data Fts5Data;
typedef struct Fts5DlidxIter Fts5DlidxIter;
typedef struct Fts5MultiSegIter Fts5MultiSegIter;
................................................................................
  Fts5Buffer term;                /* Current term */
  int iLeaf;                      /* Leaf containing terms >= current term */
  int nEmpty;                     /* Number of "empty" leaves following iLeaf */
  int bEof;                       /* Set to true at EOF */
  int bDlidx;                     /* True if there exists a dlidx */
};










































































static void fts5PutU16(u8 *aOut, u16 iVal){
  aOut[0] = (iVal>>8);
  aOut[1] = (iVal&0xFF);
}

static u16 fts5GetU16(const u8 *aIn){
................................................................................
  assert( p->rc==SQLITE_OK );
  pRet = sqlite3_malloc(nByte);
  if( pRet==0 ){
    p->rc = SQLITE_NOMEM;
  }else{
    memset(pRet, 0, nByte);
  }













  return pRet;
}

/*
** Compare the contents of the pLeft buffer with the pRight/nRight blob.
**
** Return -ve if pLeft is smaller than pRight, 0 if they are equal or
................................................................................
    if( p->pReader==0 ){
      Fts5Config *pConfig = p->pConfig;
      rc = sqlite3_blob_open(pConfig->db, 
          pConfig->zDb, p->zDataTbl, "block", iRowid, 0, &p->pReader
      );
    }



    if( rc==SQLITE_OK ){
      int nByte = sqlite3_blob_bytes(p->pReader);
      if( pBuf ){
        fts5BufferZero(pBuf);
        fts5BufferGrow(&rc, pBuf, nByte);
        rc = sqlite3_blob_read(p->pReader, pBuf->p, nByte, 0);
        if( rc==SQLITE_OK ) pBuf->n = nByte;
................................................................................
  if( p->rc==SQLITE_OK ){
    p->rc = sqlite3Fts5HashWrite(
        p->apHash[iIdx], p->iWriteRowid, iCol, iPos, pToken, nToken
    );
  }
}










































/*
** Allocate a new segment-id for the structure pStruct.
**
** If an error has already occurred, this function is a no-op. 0 is 
** returned in this case.
*/
static int fts5AllocateSegid(Fts5Index *p, Fts5Structure *pStruct){
................................................................................
  /* Flush the terms and each prefix index to disk */
  for(i=0; i<=pConfig->nPrefix; i++){
    fts5FlushOneHash(p, i, &nLeaf);
  }
  p->nPendingData = 0;
}










































































































/*
** Return a simple checksum value based on the arguments.
*/
static u64 fts5IndexEntryCksum(
  i64 iRowid, 
  int iCol, 
  int iPos, 
................................................................................
  int nTerm
){
  int i;
  u64 ret = iRowid;
  ret += (ret<<3) + iCol;
  ret += (ret<<3) + iPos;
  for(i=0; i<nTerm; i++) ret += (ret<<3) + pTerm[i];

























  return ret;
}

static void fts5BtreeIterInit(
  Fts5Index *p, 
  int iIdx,
  Fts5StructureSegment *pSeg, 
................................................................................
  if( p->rc==SQLITE_OK && iter.iLeaf!=pSeg->pgnoLast ){
    p->rc = FTS5_CORRUPT;
  }

  fts5BtreeIterFree(&iter);
}























































































































































































































































































/*
** Iterator pMulti currently points to a valid entry (not EOF). This
** function appends a copy of the position-list of the entry pMulti 
** currently points to to buffer pBuf.
**
** If an error occurs, an error code is left in p->rc. It is assumed
** no error has already occurred when this function is called.
................................................................................
      fts5DoclistIterInit(&doclist, bAsc, pIter->pDoclist);
    }
  }

  fts5StructureRelease(pStruct);
  sqlite3_free(aBuf);
}

static int fts5IndexReturn(Fts5Index *p){
  int rc = p->rc;
  p->rc = SQLITE_OK;
  return rc;
}

/*
** Run internal checks to ensure that the FTS index (a) is internally 
** consistent and (b) contains entries for which the XOR of the checksums
** as calculated by fts5IndexEntryCksum() is cksum.
**
** Return SQLITE_CORRUPT if any of the internal checks fail, or if the
** checksum does not match. Return SQLITE_OK if all checks pass without
** error, or some other SQLite error code if another error (e.g. OOM)
** occurs.
*/
int sqlite3Fts5IndexIntegrityCheck(Fts5Index *p, u64 cksum){
  Fts5Config *pConfig = p->pConfig;
  int iIdx;                       /* Used to iterate through indexes */
  int rc;                         /* Return code */
  u64 cksum2 = 0;                 /* Checksum based on contents of indexes */

  /* Check that the checksum of the index matches the argument checksum */
  for(iIdx=0; iIdx<=pConfig->nPrefix; iIdx++){
    Fts5MultiSegIter *pIter;
    Fts5Structure *pStruct = fts5StructureRead(p, iIdx);
    for(fts5MultiIterNew(p, pStruct, iIdx, 0, 0, 0, -1, 0, &pIter);
        fts5MultiIterEof(p, pIter)==0;
        fts5MultiIterNext(p, pIter, 0, 0)
    ){
      Fts5PosIter sPos;           /* Used to iterate through position list */
      int n;                      /* Size of term in bytes */
      i64 iRowid = fts5MultiIterRowid(pIter);
      char *z = (char*)fts5MultiIterTerm(pIter, &n);

      for(fts5PosIterInit(p, pIter, &sPos);
          fts5PosIterEof(p, &sPos)==0;
          fts5PosIterNext(p, &sPos)
      ){
        cksum2 ^= fts5IndexEntryCksum(iRowid, sPos.iCol, sPos.iPos, z, n);
#if 0
        fprintf(stdout, "rowid=%d ", (int)iRowid);
        fprintf(stdout, "term=%.*s ", n, z);
        fprintf(stdout, "col=%d ", sPos.iCol);
        fprintf(stdout, "off=%d\n", sPos.iPos);
        fflush(stdout);
#endif
      }
    }
    fts5MultiIterFree(p, pIter);
    fts5StructureRelease(pStruct);
  }
  rc = p->rc;
  if( rc==SQLITE_OK && cksum!=cksum2 ) rc = FTS5_CORRUPT;

  /* Check that the internal nodes of each segment match the leaves */
  for(iIdx=0; rc==SQLITE_OK && iIdx<=pConfig->nPrefix; iIdx++){
    Fts5Structure *pStruct = fts5StructureRead(p, iIdx);
    if( pStruct ){
      int iLvl, iSeg;
      for(iLvl=0; iLvl<pStruct->nLevel; iLvl++){
        for(iSeg=0; iSeg<pStruct->aLevel[iLvl].nSeg; iSeg++){
          Fts5StructureSegment *pSeg = &pStruct->aLevel[iLvl].aSeg[iSeg];
          fts5IndexIntegrityCheckSegment(p, iIdx, pSeg);
        }
      }
    }
    fts5StructureRelease(pStruct);
    rc = p->rc;
  }

  return rc;
}


/*
** Indicate that all subsequent calls to sqlite3Fts5IndexWrite() pertain
** to the document with rowid iRowid.
*/
int sqlite3Fts5IndexBeginWrite(Fts5Index *p, i64 iRowid){
  assert( p->rc==SQLITE_OK );
  if( iRowid<=p->iWriteRowid || (p->nPendingData > p->nMaxPendingData) ){
    fts5IndexFlush(p);
  }
  p->iWriteRowid = iRowid;
  return fts5IndexReturn(p);
}

/*
** Commit data to disk.
*/
int sqlite3Fts5IndexSync(Fts5Index *p, int bCommit){
  assert( p->rc==SQLITE_OK );
  fts5IndexFlush(p);
  if( bCommit ) fts5CloseReader(p);
  return fts5IndexReturn(p);
}

/*
** Discard any data stored in the in-memory hash tables. Do not write it
** to the database. Additionally, assume that the contents of the %_data
** table may have changed on disk. So any in-memory caches of %_data 
** records must be invalidated.
*/
int sqlite3Fts5IndexRollback(Fts5Index *p){
  fts5CloseReader(p);
  fts5IndexDiscardData(p);
  assert( p->rc==SQLITE_OK );
  return SQLITE_OK;
}

/*
** Open a new Fts5Index handle. If the bCreate argument is true, create
** and initialize the underlying %_data table.
**
** If successful, set *pp to point to the new object and return SQLITE_OK.
** Otherwise, set *pp to NULL and return an SQLite error code.
*/
int sqlite3Fts5IndexOpen(
  Fts5Config *pConfig, 
  int bCreate, 
  Fts5Index **pp,
  char **pzErr
){
  int rc = SQLITE_OK;
  Fts5Index *p;                   /* New object */

  *pp = p = (Fts5Index*)sqlite3_malloc(sizeof(Fts5Index));
  if( !p ) return SQLITE_NOMEM;

  memset(p, 0, sizeof(Fts5Index));
  p->pConfig = pConfig;
  p->nCrisisMerge = FTS5_CRISIS_MERGE;
  p->nWorkUnit = FTS5_WORK_UNIT;
  p->nMaxPendingData = 1024*1024;
  p->zDataTbl = sqlite3_mprintf("%s_data", pConfig->zName);
  if( p->zDataTbl==0 ){
    rc = SQLITE_NOMEM;
  }else if( bCreate ){
    int i;
    Fts5Structure s;
    rc = sqlite3Fts5CreateTable(
        pConfig, "data", "id INTEGER PRIMARY KEY, block BLOB", 0, pzErr
    );
    if( rc==SQLITE_OK ){
      memset(&s, 0, sizeof(Fts5Structure));
      for(i=0; i<pConfig->nPrefix+1; i++){
        fts5StructureWrite(p, i, &s);
      }
      rc = p->rc;
    }
    if( rc==SQLITE_OK ){
      rc = sqlite3Fts5IndexSetAverages(p, (const u8*)"", 0);
    }
  }

  assert( p->rc==SQLITE_OK || rc!=SQLITE_OK );
  if( rc ){
    sqlite3Fts5IndexClose(p, 0);
    *pp = 0;
  }
  return rc;
}

/*
** Close a handle opened by an earlier call to sqlite3Fts5IndexOpen().
*/
int sqlite3Fts5IndexClose(Fts5Index *p, int bDestroy){
  int rc = SQLITE_OK;
  if( p ){
    if( bDestroy ){
      rc = sqlite3Fts5DropTable(p->pConfig, "data");
    }
    assert( p->pReader==0 );
    sqlite3_finalize(p->pWriter);
    sqlite3_finalize(p->pDeleter);
    if( p->apHash ){
      int i;
      for(i=0; i<=p->pConfig->nPrefix; i++){
        sqlite3Fts5HashFree(p->apHash[i]);
      }
      sqlite3_free(p->apHash);
    }
    sqlite3_free(p->zDataTbl);
    sqlite3_free(p);
  }
  return rc;
}

/*
** Calculate and return a checksum that is the XOR of the index entry
** checksum of all entries that would be generated by the token specified
** by the final 5 arguments.
*/
u64 sqlite3Fts5IndexCksum(
  Fts5Config *pConfig,            /* Configuration object */
  i64 iRowid,                     /* Document term appears in */
  int iCol,                       /* Column term appears in */
  int iPos,                       /* Position term appears in */
  const char *pTerm, int nTerm    /* Term at iPos */
){
  u64 ret = 0;                    /* Return value */
  int iIdx;                       /* For iterating through indexes */

  for(iIdx=0; iIdx<=pConfig->nPrefix; iIdx++){
    int n = ((iIdx==pConfig->nPrefix) ? nTerm : pConfig->aPrefix[iIdx]);
    if( n<=nTerm ){
      ret ^= fts5IndexEntryCksum(iRowid, iCol, iPos, pTerm, n);
    }
  }

  return ret;
}

/*
** Insert or remove data to or from the index. Each time a document is 
** added to or removed from the index, this function is called one or more
** times.
**
** For an insert, it must be called once for each token in the new document.
** If the operation is a delete, it must be called (at least) once for each
** unique token in the document with an iCol value less than zero. The iPos
** argument is ignored for a delete.
*/
int sqlite3Fts5IndexWrite(
  Fts5Index *p,                   /* Index to write to */
  int iCol,                       /* Column token appears in (-ve -> delete) */
  int iPos,                       /* Position of token within column */
  const char *pToken, int nToken  /* Token to add or remove to or from index */
){
  int i;                          /* Used to iterate through indexes */
  Fts5Config *pConfig = p->pConfig;
  assert( p->rc==SQLITE_OK );

  /* Allocate hash tables if they have not already been allocated */
  if( p->apHash==0 ){
    int nHash = pConfig->nPrefix + 1;
    p->apHash = (Fts5Hash**)fts5IdxMalloc(p, sizeof(Fts5Hash*) * nHash);
    for(i=0; p->rc==SQLITE_OK && i<nHash; i++){
      p->rc = sqlite3Fts5HashNew(&p->apHash[i], &p->nPendingData);
    }
  }

  /* Add the new token to the main terms hash table. And to each of the
  ** prefix hash tables that it is large enough for. */
  fts5AddTermToHash(p, 0, iCol, iPos, pToken, nToken);
  for(i=0; i<pConfig->nPrefix; i++){
    if( nToken>=pConfig->aPrefix[i] ){
      fts5AddTermToHash(p, i+1, iCol, iPos, pToken, pConfig->aPrefix[i]);
    }
  }

  return fts5IndexReturn(p);
}

/*
** Open a new iterator to iterate though all docids that match the 
** specified token or token prefix.
*/
int sqlite3Fts5IndexQuery(
  Fts5Index *p,                   /* FTS index to query */
  const char *pToken, int nToken, /* Token (or prefix) to query for */
  int flags,                      /* Mask of FTS5INDEX_QUERY_X flags */
  Fts5IndexIter **ppIter          /* OUT: New iterator object */
){
  Fts5IndexIter *pRet;
  int iIdx = 0;

  if( flags & FTS5INDEX_QUERY_PREFIX ){
    Fts5Config *pConfig = p->pConfig;
    for(iIdx=1; iIdx<=pConfig->nPrefix; iIdx++){
................................................................................
      if( pConfig->aPrefix[iIdx-1]==nToken ) break;
    }
    if( iIdx>pConfig->nPrefix ){
      iIdx = -1;
    }
  }

  pRet = (Fts5IndexIter*)sqlite3Fts5MallocZero(&p->rc, sizeof(Fts5IndexIter));
  if( pRet ){
    memset(pRet, 0, sizeof(Fts5IndexIter));

    pRet->pIndex = p;
    if( iIdx>=0 ){
      pRet->pStruct = fts5StructureRead(p, iIdx);
      if( pRet->pStruct ){
................................................................................
    }
  }

  if( p->rc ){
    sqlite3Fts5IterClose(pRet);
    pRet = 0;
  }
  *ppIter = pRet;
  return fts5IndexReturn(p);
}

/*
** Return true if the iterator passed as the only argument is at EOF.
*/
int sqlite3Fts5IterEof(Fts5IndexIter *pIter){
  assert( pIter->pIndex->rc==SQLITE_OK );
  if( pIter->pDoclist ){ 
    return pIter->pDoclist->aPoslist==0; 
  }else{
    return fts5MultiIterEof(pIter->pIndex, pIter->pMulti);
  }
}

/*
** Move to the next matching rowid. 
*/
int sqlite3Fts5IterNext(Fts5IndexIter *pIter){
  assert( pIter->pIndex->rc==SQLITE_OK );
  if( pIter->pDoclist ){
    fts5DoclistIterNext(pIter->pDoclist);
  }else{
    fts5BufferZero(&pIter->poslist);
    fts5MultiIterNext(pIter->pIndex, pIter->pMulti, 0, 0);
  }
  return fts5IndexReturn(pIter->pIndex);
}

/*
** Move to the next matching rowid that occurs at or after iMatch. The
** definition of "at or after" depends on whether this iterator iterates
** in ascending or descending rowid order.
*/
int sqlite3Fts5IterNextFrom(Fts5IndexIter *pIter, i64 iMatch){
  if( pIter->pDoclist ){
    assert( 0 );
    /* fts5DoclistIterNextFrom(pIter->pDoclist, iMatch); */
  }else{
    fts5MultiIterNextFrom(pIter->pIndex, pIter->pMulti, iMatch);
  }
  return fts5IndexReturn(pIter->pIndex);
}

/*
** Return the current rowid.
*/
i64 sqlite3Fts5IterRowid(Fts5IndexIter *pIter){
  if( pIter->pDoclist ){
................................................................................
** Return a pointer to a buffer containing a copy of the position list for
** the current entry. Output variable *pn is set to the size of the buffer 
** in bytes before returning.
**
** The returned buffer does not include the 0x00 terminator byte stored on
** disk.
*/
int sqlite3Fts5IterPoslist(Fts5IndexIter *pIter, const u8 **pp, int *pn){
  assert( pIter->pIndex->rc==SQLITE_OK );
  if( pIter->pDoclist ){
    *pn = pIter->pDoclist->nPoslist;
    *pp = pIter->pDoclist->aPoslist;
  }else{
    Fts5Index *p = pIter->pIndex;
    fts5BufferZero(&pIter->poslist);
    fts5MultiIterPoslist(p, pIter->pMulti, 0, &pIter->poslist);


    *pn = pIter->poslist.n;
    *pp = pIter->poslist.p;
  }
  return fts5IndexReturn(pIter->pIndex);
}

/*
** Close an iterator opened by an earlier call to sqlite3Fts5IndexQuery().
*/
void sqlite3Fts5IterClose(Fts5IndexIter *pIter){
  if( pIter ){
................................................................................

/*
** Read the "averages" record into the buffer supplied as the second 
** argument. Return SQLITE_OK if successful, or an SQLite error code
** if an error occurs.
*/
int sqlite3Fts5IndexGetAverages(Fts5Index *p, Fts5Buffer *pBuf){
  assert( p->rc==SQLITE_OK );
  fts5DataReadOrBuffer(p, pBuf, FTS5_AVERAGES_ROWID);
  return fts5IndexReturn(p);
}

/*
** Replace the current "averages" record with the contents of the buffer 
** supplied as the second argument.
*/
int sqlite3Fts5IndexSetAverages(Fts5Index *p, const u8 *pData, int nData){
  assert( p->rc==SQLITE_OK );
  fts5DataWrite(p, FTS5_AVERAGES_ROWID, pData, nData);
  return fts5IndexReturn(p);
}

/*
** Return the total number of blocks this module has read from the %_data
** table since it was created.
*/
int sqlite3Fts5IndexReads(Fts5Index *p){
  return p->nRead;
}

/*
** Set the 32-bit cookie value stored at the start of all structure 
** records to the value passed as the second argument.
**
** Return SQLITE_OK if successful, or an SQLite error code if an error
** occurs.
*/
int sqlite3Fts5IndexSetCookie(Fts5Index *p, int iNew){
  int rc = SQLITE_OK;
  Fts5Config *pConfig = p->pConfig;
  u8 aCookie[4];
  int i;

  assert( p->rc==SQLITE_OK );
  sqlite3Fts5Put32(aCookie, iNew);
  for(i=0; rc==SQLITE_OK && i<=pConfig->nPrefix; i++){
    sqlite3_blob *pBlob = 0;
    i64 iRowid = FTS5_STRUCTURE_ROWID(i);
    rc = sqlite3_blob_open(
        pConfig->db, pConfig->zDb, p->zDataTbl, "block", iRowid, 1, &pBlob
    );
................................................................................
      sqlite3_blob_write(pBlob, aCookie, 4, 0);
      rc = sqlite3_blob_close(pBlob);
    }
  }

  return rc;
}

/*************************************************************************
**************************************************************************
** Below this point is the implementation of the fts5_decode() scalar
** function only.
*/

/*
** Decode a segment-data rowid from the %_data table. This function is
** the opposite of macro FTS5_SEGMENT_ROWID().
*/
static void fts5DecodeRowid(
  i64 iRowid,                     /* Rowid from %_data table */
  int *piIdx,                     /* OUT: Index */
  int *piSegid,                   /* OUT: Segment id */
  int *piHeight,                  /* OUT: Height */
  int *piPgno                     /* OUT: Page number */
){
  *piPgno = (int)(iRowid & (((i64)1 << FTS5_DATA_PAGE_B) - 1));
  iRowid >>= FTS5_DATA_PAGE_B;

  *piHeight = (int)(iRowid & (((i64)1 << FTS5_DATA_HEIGHT_B) - 1));
  iRowid >>= FTS5_DATA_HEIGHT_B;

  *piSegid = (int)(iRowid & (((i64)1 << FTS5_DATA_ID_B) - 1));
  iRowid >>= FTS5_DATA_ID_B;

  *piIdx = (int)(iRowid & (((i64)1 << FTS5_DATA_IDX_B) - 1));
}

static void fts5DebugRowid(int *pRc, Fts5Buffer *pBuf, i64 iKey){
  int iIdx,iSegid,iHeight,iPgno;  /* Rowid compenents */
  fts5DecodeRowid(iKey, &iIdx, &iSegid, &iHeight, &iPgno);

  if( iSegid==0 ){
    if( iKey==FTS5_AVERAGES_ROWID ){
      sqlite3Fts5BufferAppendPrintf(pRc, pBuf, "(averages) ");
    }else{
      sqlite3Fts5BufferAppendPrintf(pRc, pBuf, 
          "{structure idx=%d}", (int)(iKey-10)
      );
    }
  }
  else if( iHeight==FTS5_SEGMENT_MAX_HEIGHT ){
    sqlite3Fts5BufferAppendPrintf(pRc, pBuf, "(dlidx idx=%d segid=%d pgno=%d)",
        iIdx, iSegid, iPgno
    );
  }else{
    sqlite3Fts5BufferAppendPrintf(pRc, pBuf, "(idx=%d segid=%d h=%d pgno=%d)",
        iIdx, iSegid, iHeight, iPgno
    );
  }
}

static void fts5DebugStructure(
  int *pRc,                       /* IN/OUT: error code */
  Fts5Buffer *pBuf,
  Fts5Structure *p
){
  int iLvl, iSeg;                 /* Iterate through levels, segments */

  for(iLvl=0; iLvl<p->nLevel; iLvl++){
    Fts5StructureLevel *pLvl = &p->aLevel[iLvl];
    sqlite3Fts5BufferAppendPrintf(pRc, pBuf, 
        " {lvl=%d nMerge=%d", iLvl, pLvl->nMerge
    );
    for(iSeg=0; iSeg<pLvl->nSeg; iSeg++){
      Fts5StructureSegment *pSeg = &pLvl->aSeg[iSeg];
      sqlite3Fts5BufferAppendPrintf(pRc, pBuf, 
          " {id=%d h=%d leaves=%d..%d}", pSeg->iSegid, pSeg->nHeight, 
          pSeg->pgnoFirst, pSeg->pgnoLast
      );
    }
    sqlite3Fts5BufferAppendPrintf(pRc, pBuf, "}");
  }
}

/*
** This is part of the fts5_decode() debugging aid.
**
** Arguments pBlob/nBlob contain a serialized Fts5Structure object. This
** function appends a human-readable representation of the same object
** to the buffer passed as the second argument. 
*/
static void fts5DecodeStructure(
  int *pRc,                       /* IN/OUT: error code */
  Fts5Buffer *pBuf,
  const u8 *pBlob, int nBlob
){
  int rc;                         /* Return code */
  Fts5Structure *p = 0;           /* Decoded structure object */

  rc = fts5StructureDecode(pBlob, nBlob, 0, &p);
  if( rc!=SQLITE_OK ){
    *pRc = rc;
    return;
  }

  fts5DebugStructure(pRc, pBuf, p);
  fts5StructureRelease(p);
}

/*
** Buffer (a/n) is assumed to contain a list of serialized varints. Read
** each varint and append its string representation to buffer pBuf. Return
** after either the input buffer is exhausted or a 0 value is read.
**
** The return value is the number of bytes read from the input buffer.
*/
static int fts5DecodePoslist(int *pRc, Fts5Buffer *pBuf, const u8 *a, int n){
  int iOff = 0;
  while( iOff<n ){
    int iVal;
    iOff += getVarint32(&a[iOff], iVal);
    sqlite3Fts5BufferAppendPrintf(pRc, pBuf, " %d", iVal);
  }
  return iOff;
}

/*
** The start of buffer (a/n) contains the start of a doclist. The doclist
** may or may not finish within the buffer. This function appends a text
** representation of the part of the doclist that is present to buffer
** pBuf. 
**
** The return value is the number of bytes read from the input buffer.
*/
static int fts5DecodeDoclist(int *pRc, Fts5Buffer *pBuf, const u8 *a, int n){
  i64 iDocid;
  int iOff = 0;

  if( iOff<n ){
    iOff += sqlite3GetVarint(&a[iOff], (u64*)&iDocid);
    sqlite3Fts5BufferAppendPrintf(pRc, pBuf, " rowid=%lld", iDocid);
  }
  while( iOff<n ){
    int nPos;
    iOff += getVarint32(&a[iOff], nPos);
    iOff += fts5DecodePoslist(pRc, pBuf, &a[iOff], MIN(n-iOff, nPos));
    if( iOff<n ){
      i64 iDelta;
      iOff += sqlite3GetVarint(&a[iOff], (u64*)&iDelta);
      if( iDelta==0 ) return iOff;
      iDocid -= iDelta;
      sqlite3Fts5BufferAppendPrintf(pRc, pBuf, " rowid=%lld", iDocid);
    }
  }

  return iOff;
}

/*
** The implementation of user-defined scalar function fts5_decode().
*/
static void fts5DecodeFunction(
  sqlite3_context *pCtx,          /* Function call context */
  int nArg,                       /* Number of args (always 2) */
  sqlite3_value **apVal           /* Function arguments */
){
  i64 iRowid;                     /* Rowid for record being decoded */
  int iIdx,iSegid,iHeight,iPgno;  /* Rowid components */
  const u8 *a; int n;             /* Record to decode */
  Fts5Buffer s;                   /* Build up text to return here */
  int rc = SQLITE_OK;             /* Return code */

  assert( nArg==2 );
  memset(&s, 0, sizeof(Fts5Buffer));
  iRowid = sqlite3_value_int64(apVal[0]);
  n = sqlite3_value_bytes(apVal[1]);
  a = sqlite3_value_blob(apVal[1]);
  fts5DecodeRowid(iRowid, &iIdx, &iSegid, &iHeight, &iPgno);

  fts5DebugRowid(&rc, &s, iRowid);
  if( iHeight==FTS5_SEGMENT_MAX_HEIGHT ){
    int i = 0;
    i64 iPrev;
    if( n>0 ){
      i = getVarint(&a[i], (u64*)&iPrev);
      sqlite3Fts5BufferAppendPrintf(&rc, &s, " %lld", iPrev);
    }
    while( i<n ){
      i64 iVal;
      i += getVarint(&a[i], (u64*)&iVal);
      if( iVal==0 ){
        sqlite3Fts5BufferAppendPrintf(&rc, &s, " x");
      }else{
        iPrev = iPrev - iVal;
        sqlite3Fts5BufferAppendPrintf(&rc, &s, " %lld", iPrev);
      }
    }

  }else
  if( iSegid==0 ){
    if( iRowid==FTS5_AVERAGES_ROWID ){
      /* todo */
    }else{
      fts5DecodeStructure(&rc, &s, a, n);
    }
  }else{

    Fts5Buffer term;
    memset(&term, 0, sizeof(Fts5Buffer));

    if( iHeight==0 ){
      int iTermOff = 0;
      int iRowidOff = 0;
      int iOff;
      int nKeep = 0;

      iRowidOff = fts5GetU16(&a[0]);
      iTermOff = fts5GetU16(&a[2]);

      if( iRowidOff ){
        iOff = iRowidOff;
      }else if( iTermOff ){
        iOff = iTermOff;
      }else{
        iOff = n;
      }
      fts5DecodePoslist(&rc, &s, &a[4], iOff-4);


      assert( iRowidOff==0 || iOff==iRowidOff );
      if( iRowidOff ){
        iOff += fts5DecodeDoclist(&rc, &s, &a[iOff], n-iOff);
      }

      assert( iTermOff==0 || iOff==iTermOff );
      while( iOff<n ){
        int nByte;
        iOff += getVarint32(&a[iOff], nByte);
        term.n= nKeep;
        fts5BufferAppendBlob(&rc, &term, nByte, &a[iOff]);
        iOff += nByte;

        sqlite3Fts5BufferAppendPrintf(
            &rc, &s, " term=%.*s", term.n, (const char*)term.p
        );
        iOff += fts5DecodeDoclist(&rc, &s, &a[iOff], n-iOff);
        if( iOff<n ){
          iOff += getVarint32(&a[iOff], nKeep);
        }
      }
      fts5BufferFree(&term);
    }else{
      Fts5NodeIter ss;
      for(fts5NodeIterInit(a, n, &ss); ss.aData; fts5NodeIterNext(&rc, &ss)){
        if( ss.term.n==0 ){
          sqlite3Fts5BufferAppendPrintf(&rc, &s, " left=%d", ss.iChild);
        }else{
          sqlite3Fts5BufferAppendPrintf(&rc,&s, " \"%.*s\"", 
              ss.term.n, ss.term.p
          );
        }
        if( ss.nEmpty ){
          sqlite3Fts5BufferAppendPrintf(&rc, &s, " empty=%d%s", ss.nEmpty,
              ss.bDlidx ? "*" : ""
          );
        }
      }
      fts5NodeIterFree(&ss);
    }
  }
  
  if( rc==SQLITE_OK ){
    sqlite3_result_text(pCtx, (const char*)s.p, s.n, SQLITE_TRANSIENT);
  }else{
    sqlite3_result_error_code(pCtx, rc);
  }
  fts5BufferFree(&s);
}


/*
** This is called as part of registering the FTS5 module with database
** connection db. It registers several user-defined scalar functions useful
** with FTS5.
**
** If successful, SQLITE_OK is returned. If an error occurs, some other
** SQLite error code is returned instead.
*/
int sqlite3Fts5IndexInit(sqlite3 *db){
  int rc = sqlite3_create_function(
      db, "fts5_decode", 2, SQLITE_UTF8, 0, fts5DecodeFunction, 0, 0
  );
  return rc;
}

}

/*
** Close a handle opened by an earlier call to sqlite3Fts5StorageOpen().
*/
int sqlite3Fts5StorageClose(Fts5Storage *p, int bDestroy){
  int rc = SQLITE_OK;

  int i;

  /* Finalize all SQL statements */
  for(i=0; i<ArraySize(p->aStmt); i++){
    sqlite3_finalize(p->aStmt[i]);
  }

  /* If required, remove the shadow tables from the database */
  if( bDestroy ){
    rc = sqlite3Fts5DropTable(p->pConfig, "content");
    if( rc==SQLITE_OK ) rc = sqlite3Fts5DropTable(p->pConfig, "docsize");
    if( rc==SQLITE_OK ) rc = sqlite3Fts5DropTable(p->pConfig, "config");
  }

  sqlite3_free(p);

  return rc;
}

typedef struct Fts5InsertCtx Fts5InsertCtx;
struct Fts5InsertCtx {
  Fts5Storage *pStorage;
  int iCol;
................................................................................
  int iStart,                     /* Start offset of token */
  int iEnd,                       /* End offset of token */
  int iPos                        /* Position offset of token */
){
  Fts5InsertCtx *pCtx = (Fts5InsertCtx*)pContext;
  Fts5Index *pIdx = pCtx->pStorage->pIndex;
  pCtx->szCol = iPos+1;
  sqlite3Fts5IndexWrite(pIdx, pCtx->iCol, iPos, pToken, nToken);
  return SQLITE_OK;
}

/*
** If a row with rowid iDel is present in the %_content table, add the
** delete-markers to the FTS index necessary to delete it. Do not actually
** remove the %_content row at this time though.
*/
................................................................................
    int rc2;
    sqlite3_bind_int64(pSeek, 1, iDel);
    if( sqlite3_step(pSeek)==SQLITE_ROW ){
      int iCol;
      Fts5InsertCtx ctx;
      ctx.pStorage = p;
      ctx.iCol = -1;
      sqlite3Fts5IndexBeginWrite(p->pIndex, iDel);
      for(iCol=1; iCol<=pConfig->nCol; iCol++){
        rc = sqlite3Fts5Tokenize(pConfig, 
            (const char*)sqlite3_column_text(pSeek, iCol),
            sqlite3_column_bytes(pSeek, iCol),
            (void*)&ctx,
            fts5StorageInsertCallback
        );
        p->aTotalSize[iCol-1] -= (i64)ctx.szCol;
................................................................................
  if( rc==SQLITE_OK ){
    sqlite3_step(pInsert);
    rc = sqlite3_reset(pInsert);
  }
  *piRowid = sqlite3_last_insert_rowid(pConfig->db);

  /* Add new entries to the FTS index */

  sqlite3Fts5IndexBeginWrite(p->pIndex, *piRowid);
  ctx.pStorage = p;

  for(ctx.iCol=0; rc==SQLITE_OK && ctx.iCol<pConfig->nCol; ctx.iCol++){
    ctx.szCol = 0;
    rc = sqlite3Fts5Tokenize(pConfig, 
        (const char*)sqlite3_value_text(apVal[ctx.iCol+2]),
        sqlite3_value_bytes(apVal[ctx.iCol+2]),
        (void*)&ctx,
        fts5StorageInsertCallback

}

/*
** Close a handle opened by an earlier call to sqlite3Fts5StorageOpen().
*/
int sqlite3Fts5StorageClose(Fts5Storage *p, int bDestroy){
  int rc = SQLITE_OK;
  if( p ){
    int i;

    /* Finalize all SQL statements */
    for(i=0; i<ArraySize(p->aStmt); i++){
      sqlite3_finalize(p->aStmt[i]);
    }

    /* If required, remove the shadow tables from the database */
    if( bDestroy ){
      rc = sqlite3Fts5DropTable(p->pConfig, "content");
      if( rc==SQLITE_OK ) rc = sqlite3Fts5DropTable(p->pConfig, "docsize");
      if( rc==SQLITE_OK ) rc = sqlite3Fts5DropTable(p->pConfig, "config");
    }

    sqlite3_free(p);
  }
  return rc;
}

typedef struct Fts5InsertCtx Fts5InsertCtx;
struct Fts5InsertCtx {
  Fts5Storage *pStorage;
  int iCol;
................................................................................
  int iStart,                     /* Start offset of token */
  int iEnd,                       /* End offset of token */
  int iPos                        /* Position offset of token */
){
  Fts5InsertCtx *pCtx = (Fts5InsertCtx*)pContext;
  Fts5Index *pIdx = pCtx->pStorage->pIndex;
  pCtx->szCol = iPos+1;
  return sqlite3Fts5IndexWrite(pIdx, pCtx->iCol, iPos, pToken, nToken);

}

/*
** If a row with rowid iDel is present in the %_content table, add the
** delete-markers to the FTS index necessary to delete it. Do not actually
** remove the %_content row at this time though.
*/
................................................................................
    int rc2;
    sqlite3_bind_int64(pSeek, 1, iDel);
    if( sqlite3_step(pSeek)==SQLITE_ROW ){
      int iCol;
      Fts5InsertCtx ctx;
      ctx.pStorage = p;
      ctx.iCol = -1;
      rc = sqlite3Fts5IndexBeginWrite(p->pIndex, iDel);
      for(iCol=1; rc==SQLITE_OK && iCol<=pConfig->nCol; iCol++){
        rc = sqlite3Fts5Tokenize(pConfig, 
            (const char*)sqlite3_column_text(pSeek, iCol),
            sqlite3_column_bytes(pSeek, iCol),
            (void*)&ctx,
            fts5StorageInsertCallback
        );
        p->aTotalSize[iCol-1] -= (i64)ctx.szCol;
................................................................................
  if( rc==SQLITE_OK ){
    sqlite3_step(pInsert);
    rc = sqlite3_reset(pInsert);
  }
  *piRowid = sqlite3_last_insert_rowid(pConfig->db);

  /* Add new entries to the FTS index */
  if( rc==SQLITE_OK ){
    rc = sqlite3Fts5IndexBeginWrite(p->pIndex, *piRowid);
    ctx.pStorage = p;
  }
  for(ctx.iCol=0; rc==SQLITE_OK && ctx.iCol<pConfig->nCol; ctx.iCol++){
    ctx.szCol = 0;
    rc = sqlite3Fts5Tokenize(pConfig, 
        (const char*)sqlite3_value_text(apVal[ctx.iCol+2]),
        sqlite3_value_bytes(apVal[ctx.iCol+2]),
        (void*)&ctx,
        fts5StorageInsertCallback

# 2014 June 17
#
# 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.
#
#*************************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this script is testing the FTS5 module.
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
source $testdir/malloc_common.tcl
set testprefix fts5fault1

# If SQLITE_ENABLE_FTS3 is defined, omit this file.
ifcapable !fts5 {
  finish_test
  return
}

faultsim_save_and_close
do_faultsim_test 1 -prep {
  faultsim_restore_and_reopen
} -body {
  execsql { CREATE VIRTUAL TABLE t1 USING fts5(a) }
} -test {
  faultsim_test_result {0 {}} 
}



finish_test

  fts3varint.test
  fts4growth.test fts4growth2.test
}

test_suite "fts5" -prefix "" -description {
  All FTS5 tests.
} -files {
  fts5aa.test fts5ab.test fts5ac.test fts5ad.test fts5ae.test fts5ea.test
  fts5af.test fts5ag.test fts5ah.test fts5ai.test fts5aj.test




}

test_suite "nofaultsim" -prefix "" -description {
  "Very" quick test suite. Runs in less than 5 minutes on a workstation. 
  This test suite is the same as the "quick" tests, except that some files
  that test malloc and IO errors are omitted.
} -files [

  fts3varint.test
  fts4growth.test fts4growth2.test
}

test_suite "fts5" -prefix "" -description {
  All FTS5 tests.
} -files {
  fts5aa.test fts5ab.test fts5ac.test fts5ad.test fts5ae.test 
  fts5af.test fts5ag.test fts5ah.test fts5ai.test fts5aj.test
  fts5ak.test fts5al.test
  fts5ea.test

  fts5fault1.test
}

test_suite "nofaultsim" -prefix "" -description {
  "Very" quick test suite. Runs in less than 5 minutes on a workstation. 
  This test suite is the same as the "quick" tests, except that some files
  that test malloc and IO errors are omitted.
} -files [