assert( p->nPendingData==0 );

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



  sqlite3_free(p->zSelectLeaves);


  /* Invoke the tokenizer destructor to free the tokenizer. */
  p->pTokenizer->pModule->xDestroy(p->pTokenizer);

  sqlite3_free(p);
  return SQLITE_OK;
}
................................................................................
  Fts3Cursor *pCsr = (Fts3Cursor *)pCursor;
  sqlite3_finalize(pCsr->pStmt);
  sqlite3Fts3ExprFree(pCsr->pExpr);
  sqlite3_free(pCsr->aDoclist);
  sqlite3_free(pCsr);
  return SQLITE_OK;
}




















static int fts3NextMethod(sqlite3_vtab_cursor *pCursor){
  int rc;                         /* Return code */

  Fts3Cursor *pCsr = (Fts3Cursor *)pCursor;

  if( pCsr->aDoclist==0 ){
    if( SQLITE_ROW==sqlite3_step(pCsr->pStmt) ){
      rc = SQLITE_OK;
    }else{
      pCsr->isEof = 1;
      rc = sqlite3_reset(pCsr->pStmt);
    }
  }else if( pCsr->pNextId>=&pCsr->aDoclist[pCsr->nDoclist] ){
    pCsr->isEof = 1;
    rc = SQLITE_OK;
  }else{
    sqlite3_reset(pCsr->pStmt);
    fts3GetDeltaVarint(&pCsr->pNextId, &pCsr->iPrevId);
    sqlite3_bind_int64(pCsr->pStmt, 1, pCsr->iPrevId);
    if( SQLITE_ROW==sqlite3_step(pCsr->pStmt) ){
      rc = SQLITE_OK;
    }else{
      pCsr->isEof = 1;
      if( SQLITE_OK==(rc = sqlite3_reset(pCsr->pStmt)) ){
        rc = SQLITE_ERROR;
      }
    }
  }
  return rc;
}


/*
** The buffer pointed to by argument zNode (size nNode bytes) contains the
................................................................................
    if( pNew ){
      if( nSegment==nAlloc ){
        nAlloc += 16;
        Fts3SegReader **pArray = (Fts3SegReader **)sqlite3_realloc(
            apSegment, nAlloc*sizeof(Fts3SegReader *)
        );
        if( !pArray ){
          sqlite3Fts3SegReaderFree(pNew);
          rc = SQLITE_NOMEM;
          goto finished;
        }
        apSegment = pArray;
      }
      apSegment[nSegment++] = pNew;
    }
................................................................................
  }else{
    sqlite3_free(tsc.aOutput);
  }

finished:
  sqlite3_reset(pStmt);
  for(i=0; i<nSegment; i++){
    sqlite3Fts3SegReaderFree(apSegment[i]);
  }
  sqlite3_free(apSegment);
  return rc;
}


/* 
................................................................................

/* This is the xColumn method of the virtual table.  The SQLite
** core calls this method during a query when it needs the value
** of a column from the virtual table.  This method needs to use
** one of the sqlite3_result_*() routines to store the requested
** value back in the pContext.
*/
static int fulltextColumn(sqlite3_vtab_cursor *pCursor,
                          sqlite3_context *pContext, int idxCol){
  Fts3Cursor *c = (Fts3Cursor *) pCursor;
  Fts3Table *v = cursor_vtab(c);





  if( idxCol<v->nColumn ){
    sqlite3_value *pVal = sqlite3_column_value(c->pStmt, idxCol+1);
    sqlite3_result_value(pContext, pVal);
  }else if( idxCol==v->nColumn ){
    /* The extra column whose name is the same as the table.
    ** Return a blob which is a pointer to the cursor
................................................................................
** This is the xRowid method. The SQLite core calls this routine to
** retrieve the rowid for the current row of the result set. fts3
** exposes %_content.docid as the rowid for the virtual table. The
** rowid should be written to *pRowid.
*/
static int fts3RowidMethod(sqlite3_vtab_cursor *pCursor, sqlite_int64 *pRowid){
  Fts3Cursor *pCsr = (Fts3Cursor *) pCursor;



  *pRowid = sqlite3_column_int64(pCsr->pStmt, 0);

  return SQLITE_OK;
}

/* 
** This function is the implementation of the xUpdate callback used by 
** FTS3 virtual tables. It is invoked by SQLite each time a row is to be
** inserted, updated or deleted.
................................................................................
  /* xDisconnect   */ fts3DisconnectMethod,
  /* xDestroy      */ fts3DestroyMethod,
  /* xOpen         */ fts3OpenMethod,
  /* xClose        */ fulltextClose,
  /* xFilter       */ fts3FilterMethod,
  /* xNext         */ fts3NextMethod,
  /* xEof          */ fts3EofMethod,
  /* xColumn       */ fulltextColumn,
  /* xRowid        */ fts3RowidMethod,
  /* xUpdate       */ fts3UpdateMethod,
  /* xBegin        */ fts3BeginMethod,
  /* xSync         */ fts3SyncMethod,
  /* xCommit       */ fts3CommitMethod,
  /* xRollback     */ fts3RollbackMethod,
  /* xFindFunction */ fts3FindFunctionMethod,

  assert( p->nPendingData==0 );

  /* Free any prepared statements held */
  for(i=0; i<SizeofArray(p->aStmt); i++){
    sqlite3_finalize(p->aStmt[i]);
  }
  for(i=0; i<p->nLeavesStmt; i++){
    sqlite3_finalize(p->aLeavesStmt[i]);
  }
  sqlite3_free(p->zSelectLeaves);
  sqlite3_free(p->aLeavesStmt);

  /* Invoke the tokenizer destructor to free the tokenizer. */
  p->pTokenizer->pModule->xDestroy(p->pTokenizer);

  sqlite3_free(p);
  return SQLITE_OK;
}
................................................................................
  Fts3Cursor *pCsr = (Fts3Cursor *)pCursor;
  sqlite3_finalize(pCsr->pStmt);
  sqlite3Fts3ExprFree(pCsr->pExpr);
  sqlite3_free(pCsr->aDoclist);
  sqlite3_free(pCsr);
  return SQLITE_OK;
}

static int fts3CursorSeek(Fts3Cursor *pCsr){
  if( pCsr->isRequireSeek ){
    pCsr->isRequireSeek = 0;
    sqlite3_bind_int64(pCsr->pStmt, 1, pCsr->iPrevId);
    if( SQLITE_ROW==sqlite3_step(pCsr->pStmt) ){
      return SQLITE_OK;
    }else{
      int rc;
      pCsr->isEof = 1;
      if( SQLITE_OK==(rc = sqlite3_reset(pCsr->pStmt)) ){
        rc = SQLITE_ERROR;
      }
      return rc;
    }
  }else{
    return SQLITE_OK;
  }
}

static int fts3NextMethod(sqlite3_vtab_cursor *pCursor){

  int rc = SQLITE_OK;             /* Return code */
  Fts3Cursor *pCsr = (Fts3Cursor *)pCursor;

  if( pCsr->aDoclist==0 ){
    if( SQLITE_ROW!=sqlite3_step(pCsr->pStmt) ){


      pCsr->isEof = 1;
      rc = sqlite3_reset(pCsr->pStmt);
    }
  }else if( pCsr->pNextId>=&pCsr->aDoclist[pCsr->nDoclist] ){
    pCsr->isEof = 1;

  }else{
    sqlite3_reset(pCsr->pStmt);
    fts3GetDeltaVarint(&pCsr->pNextId, &pCsr->iPrevId);




    pCsr->isRequireSeek = 1;




  }
  return rc;
}


/*
** The buffer pointed to by argument zNode (size nNode bytes) contains the
................................................................................
    if( pNew ){
      if( nSegment==nAlloc ){
        nAlloc += 16;
        Fts3SegReader **pArray = (Fts3SegReader **)sqlite3_realloc(
            apSegment, nAlloc*sizeof(Fts3SegReader *)
        );
        if( !pArray ){
          sqlite3Fts3SegReaderFree(p, pNew);
          rc = SQLITE_NOMEM;
          goto finished;
        }
        apSegment = pArray;
      }
      apSegment[nSegment++] = pNew;
    }
................................................................................
  }else{
    sqlite3_free(tsc.aOutput);
  }

finished:
  sqlite3_reset(pStmt);
  for(i=0; i<nSegment; i++){
    sqlite3Fts3SegReaderFree(p, apSegment[i]);
  }
  sqlite3_free(apSegment);
  return rc;
}


/* 
................................................................................

/* This is the xColumn method of the virtual table.  The SQLite
** core calls this method during a query when it needs the value
** of a column from the virtual table.  This method needs to use
** one of the sqlite3_result_*() routines to store the requested
** value back in the pContext.
*/
static int fts3ColumnMethod(sqlite3_vtab_cursor *pCursor,
                          sqlite3_context *pContext, int idxCol){
  Fts3Cursor *c = (Fts3Cursor *) pCursor;
  Fts3Table *v = cursor_vtab(c);
  int rc = fts3CursorSeek(c);
  if( rc!=SQLITE_OK ){
    return rc;
  }

  if( idxCol<v->nColumn ){
    sqlite3_value *pVal = sqlite3_column_value(c->pStmt, idxCol+1);
    sqlite3_result_value(pContext, pVal);
  }else if( idxCol==v->nColumn ){
    /* The extra column whose name is the same as the table.
    ** Return a blob which is a pointer to the cursor
................................................................................
** This is the xRowid method. The SQLite core calls this routine to
** retrieve the rowid for the current row of the result set. fts3
** exposes %_content.docid as the rowid for the virtual table. The
** rowid should be written to *pRowid.
*/
static int fts3RowidMethod(sqlite3_vtab_cursor *pCursor, sqlite_int64 *pRowid){
  Fts3Cursor *pCsr = (Fts3Cursor *) pCursor;
  if( pCsr->aDoclist ){
    *pRowid = pCsr->iPrevId;
  }else{
    *pRowid = sqlite3_column_int64(pCsr->pStmt, 0);
  }
  return SQLITE_OK;
}

/* 
** This function is the implementation of the xUpdate callback used by 
** FTS3 virtual tables. It is invoked by SQLite each time a row is to be
** inserted, updated or deleted.
................................................................................
  /* xDisconnect   */ fts3DisconnectMethod,
  /* xDestroy      */ fts3DestroyMethod,
  /* xOpen         */ fts3OpenMethod,
  /* xClose        */ fulltextClose,
  /* xFilter       */ fts3FilterMethod,
  /* xNext         */ fts3NextMethod,
  /* xEof          */ fts3EofMethod,
  /* xColumn       */ fts3ColumnMethod,
  /* xRowid        */ fts3RowidMethod,
  /* xUpdate       */ fts3UpdateMethod,
  /* xBegin        */ fts3BeginMethod,
  /* xSync         */ fts3SyncMethod,
  /* xCommit       */ fts3CommitMethod,
  /* xRollback     */ fts3RollbackMethod,
  /* xFindFunction */ fts3FindFunctionMethod,

** A connection to a fulltext index is an instance of the following
** structure. The xCreate and xConnect methods create an instance
** of this structure and xDestroy and xDisconnect free that instance.
** All other methods receive a pointer to the structure as one of their
** arguments.
*/
struct Fts3Table {
  sqlite3_vtab base;               /* Base class used by SQLite core */
  sqlite3 *db;                     /* The database connection */
  const char *zDb;                 /* logical database name */
  const char *zName;               /* virtual table name */
  int nColumn;                     /* number of columns in virtual table */
  char **azColumn;                 /* column names.  malloced */
  sqlite3_tokenizer *pTokenizer;   /* tokenizer for inserts and queries */

  /* Precompiled statements used by the implementation. Each of these 
  ** statements is run and reset within a single virtual table API call. 
  */
  sqlite3_stmt *aStmt[18];

  /* Pointer to string containing the SQL:
  **
  ** "SELECT block FROM %_segments WHERE blockid BETWEEN ? AND ? 
  **    ORDER BY blockid"
  */
  char *zSelectLeaves;





  /* The following hash table is used to buffer pending index updates during
  ** transactions. Variable nPendingData estimates the memory size of the 
  ** pending data, including hash table overhead, but not malloc overhead. 
  ** When nPendingData exceeds FTS3_MAX_PENDING_DATA, the buffer is flushed 
  ** automatically. Variable iPrevDocid is the docid of the most recently
  ** inserted record.
................................................................................
** the xOpen method. Cursors are destroyed using the xClose method.
*/
struct Fts3Cursor {
  sqlite3_vtab_cursor base;       /* Base class used by SQLite core */
  int eType;                      /* Search strategy (see below) */
  sqlite3_stmt *pStmt;            /* Prepared statement in use by the cursor */
  int isEof;                      /* True if at End Of Results */

  Fts3Expr *pExpr;                /* Parsed MATCH query string */
  sqlite3_int64 iPrevId;          /* Previous id read from aDoclist */
  char *pNextId;                  /* Pointer into the body of aDoclist */
  char *aDoclist;                 /* List of docids for full-text queries */
  int nDoclist;                   /* Size of buffer at aDoclist */
};

................................................................................
/* fts3_write.c */
int sqlite3Fts3UpdateMethod(sqlite3_vtab*,int,sqlite3_value**,sqlite3_int64*);
int sqlite3Fts3PendingTermsFlush(Fts3Table *);
void sqlite3Fts3PendingTermsClear(Fts3Table *);
int sqlite3Fts3Optimize(Fts3Table *);
int sqlite3Fts3SegReaderNew(Fts3Table *,int, sqlite3_int64,
  sqlite3_int64, sqlite3_int64, const char *, int, Fts3SegReader**);
void sqlite3Fts3SegReaderFree(Fts3SegReader *);
int sqlite3Fts3SegReaderIterate(
  Fts3Table *, Fts3SegReader **, int, Fts3SegFilter *,
  int (*)(Fts3Table *, void *, char *, int, char *, int),  void *
);
int sqlite3Fts3ReadBlock(Fts3Table*, sqlite3_int64, char const**, int*);
int sqlite3Fts3AllSegdirs(Fts3Table*, sqlite3_stmt **);

** A connection to a fulltext index is an instance of the following
** structure. The xCreate and xConnect methods create an instance
** of this structure and xDestroy and xDisconnect free that instance.
** All other methods receive a pointer to the structure as one of their
** arguments.
*/
struct Fts3Table {
  sqlite3_vtab base;              /* Base class used by SQLite core */
  sqlite3 *db;                    /* The database connection */
  const char *zDb;                /* logical database name */
  const char *zName;              /* virtual table name */
  int nColumn;                    /* number of columns in virtual table */
  char **azColumn;                /* column names.  malloced */
  sqlite3_tokenizer *pTokenizer;  /* tokenizer for inserts and queries */

  /* Precompiled statements used by the implementation. Each of these 
  ** statements is run and reset within a single virtual table API call. 
  */
  sqlite3_stmt *aStmt[18];

  /* Pointer to string containing the SQL:
  **
  ** "SELECT block FROM %_segments WHERE blockid BETWEEN ? AND ? 
  **    ORDER BY blockid"
  */
  char *zSelectLeaves;
  int nLeavesStmt;                /* Valid statements in aLeavesStmt */
  int nLeavesTotal;               /* Total number of prepared leaves stmts */
  int nLeavesAlloc;               /* Allocated size of aLeavesStmt */
  sqlite3_stmt **aLeavesStmt;     /* Array of prepared zSelectLeaves stmts */

  /* The following hash table is used to buffer pending index updates during
  ** transactions. Variable nPendingData estimates the memory size of the 
  ** pending data, including hash table overhead, but not malloc overhead. 
  ** When nPendingData exceeds FTS3_MAX_PENDING_DATA, the buffer is flushed 
  ** automatically. Variable iPrevDocid is the docid of the most recently
  ** inserted record.
................................................................................
** the xOpen method. Cursors are destroyed using the xClose method.
*/
struct Fts3Cursor {
  sqlite3_vtab_cursor base;       /* Base class used by SQLite core */
  int eType;                      /* Search strategy (see below) */
  sqlite3_stmt *pStmt;            /* Prepared statement in use by the cursor */
  int isEof;                      /* True if at End Of Results */
  int isRequireSeek;              /* True if must seek pStmt to %_content row */
  Fts3Expr *pExpr;                /* Parsed MATCH query string */
  sqlite3_int64 iPrevId;          /* Previous id read from aDoclist */
  char *pNextId;                  /* Pointer into the body of aDoclist */
  char *aDoclist;                 /* List of docids for full-text queries */
  int nDoclist;                   /* Size of buffer at aDoclist */
};

................................................................................
/* fts3_write.c */
int sqlite3Fts3UpdateMethod(sqlite3_vtab*,int,sqlite3_value**,sqlite3_int64*);
int sqlite3Fts3PendingTermsFlush(Fts3Table *);
void sqlite3Fts3PendingTermsClear(Fts3Table *);
int sqlite3Fts3Optimize(Fts3Table *);
int sqlite3Fts3SegReaderNew(Fts3Table *,int, sqlite3_int64,
  sqlite3_int64, sqlite3_int64, const char *, int, Fts3SegReader**);
void sqlite3Fts3SegReaderFree(Fts3Table *, Fts3SegReader *);
int sqlite3Fts3SegReaderIterate(
  Fts3Table *, Fts3SegReader **, int, Fts3SegFilter *,
  int (*)(Fts3Table *, void *, char *, int, char *, int),  void *
);
int sqlite3Fts3ReadBlock(Fts3Table*, sqlite3_int64, char const**, int*);
int sqlite3Fts3AllSegdirs(Fts3Table*, sqlite3_stmt **);

  }
}

/*
** Free all allocations associated with the iterator passed as the first
** argument.
*/
void sqlite3Fts3SegReaderFree(Fts3SegReader *pReader){
  if( pReader ){


    sqlite3_finalize(pReader->pStmt);


    sqlite3_free(pReader->zTerm);
    sqlite3_free(pReader);
  }
}

int sqlite3Fts3SegReaderNew(
  Fts3Table *p,                   /* Virtual table handle */
................................................................................

  if( nExtra ){
    /* The entire segment is stored in the root node. */
    pReader->aNode = (char *)&pReader[1];
    pReader->nNode = nRoot;
    memcpy(pReader->aNode, zRoot, nRoot);
  }else{

    if( !p->zSelectLeaves ){
      p->zSelectLeaves = sqlite3_mprintf(
          "SELECT block FROM %Q.'%q_segments' WHERE blockid BETWEEN ? AND ? "
          "ORDER BY blockid", p->zDb, p->zName
      );
      if( !p->zSelectLeaves ){
        rc = SQLITE_NOMEM;
        goto finished;
      }
    }













    rc = sqlite3_prepare_v2(p->db, p->zSelectLeaves, -1, &pReader->pStmt, 0);
    if( rc!=SQLITE_OK ){
      goto finished;




    }
    sqlite3_bind_int64(pReader->pStmt, 1, iStartLeaf);
    sqlite3_bind_int64(pReader->pStmt, 2, iEndLeaf);
  }
  rc = fts3SegReaderNext(pReader);

 finished:
  if( rc==SQLITE_OK ){
    *ppReader = pReader;
  }else{
    sqlite3Fts3SegReaderFree(pReader);
  }
  return rc;
}


/*
** The second argument to this function is expected to be a statement of
................................................................................
    rc = fts3SegWriterFlush(p, pWriter, iNewLevel, iIdx);
  }

 finished:
  fts3SegWriterFree(pWriter);
  if( apSegment ){
    for(i=0; i<nSegment; i++){
      sqlite3Fts3SegReaderFree(apSegment[i]);
    }
    sqlite3_free(apSegment);
  }
  sqlite3_reset(pStmt);
  return rc;
}

  }
}

/*
** Free all allocations associated with the iterator passed as the first
** argument.
*/
void sqlite3Fts3SegReaderFree(Fts3Table *p, Fts3SegReader *pReader){
  if( pReader ){
    if( pReader->pStmt ){
      assert( p->nLeavesStmt<p->nLeavesTotal );
      sqlite3_reset(pReader->pStmt);
      p->aLeavesStmt[p->nLeavesStmt++] = pReader->pStmt;
    }
    sqlite3_free(pReader->zTerm);
    sqlite3_free(pReader);
  }
}

int sqlite3Fts3SegReaderNew(
  Fts3Table *p,                   /* Virtual table handle */
................................................................................

  if( nExtra ){
    /* The entire segment is stored in the root node. */
    pReader->aNode = (char *)&pReader[1];
    pReader->nNode = nRoot;
    memcpy(pReader->aNode, zRoot, nRoot);
  }else{
    sqlite3_stmt *pStmt;
    if( !p->zSelectLeaves ){
      p->zSelectLeaves = sqlite3_mprintf(
          "SELECT block FROM %Q.'%q_segments' WHERE blockid BETWEEN ? AND ? "
          "ORDER BY blockid", p->zDb, p->zName
      );
      if( !p->zSelectLeaves ){
        rc = SQLITE_NOMEM;
        goto finished;
      }
    }
    if( p->nLeavesStmt==0 ){
      if( p->nLeavesTotal==p->nLeavesAlloc ){
        int nNew = p->nLeavesAlloc + 16;
        sqlite3_stmt **aNew = (sqlite3_stmt **)sqlite3_realloc(
            p->aLeavesStmt, nNew*sizeof(sqlite3_stmt *)
        );
        if( !aNew ){
          rc = SQLITE_NOMEM;
          goto finished;
        }
        p->nLeavesAlloc = nNew;
        p->aLeavesStmt = aNew;
      }
      rc = sqlite3_prepare_v2(p->db, p->zSelectLeaves, -1, &pReader->pStmt, 0);
      if( rc!=SQLITE_OK ){
        goto finished;
      }
      p->nLeavesTotal++;
    }else{
      pReader->pStmt = p->aLeavesStmt[--p->nLeavesStmt];
    }
    sqlite3_bind_int64(pReader->pStmt, 1, iStartLeaf);
    sqlite3_bind_int64(pReader->pStmt, 2, iEndLeaf);
  }
  rc = fts3SegReaderNext(pReader);

 finished:
  if( rc==SQLITE_OK ){
    *ppReader = pReader;
  }else{
    sqlite3Fts3SegReaderFree(p, pReader);
  }
  return rc;
}


/*
** The second argument to this function is expected to be a statement of
................................................................................
    rc = fts3SegWriterFlush(p, pWriter, iNewLevel, iIdx);
  }

 finished:
  fts3SegWriterFree(pWriter);
  if( apSegment ){
    for(i=0; i<nSegment; i++){
      sqlite3Fts3SegReaderFree(p, apSegment[i]);
    }
    sqlite3_free(apSegment);
  }
  sqlite3_reset(pStmt);
  return rc;
}