SQLite

/*
** Virtual-table cursor object.
**
** iSpecial:
**   If this is a 'special' query (refer to function fts5SpecialMatch()), 
**   then this variable contains the result of the query. 
**
** iFirstRowid, iLastRowid:
**   These variables are only used for FTS5_PLAN_MATCH cursors. Assuming the
**   cursor iterates in ascending order of rowids, iFirstRowid is the lower
**   limit of rowids to return, and iLastRowid the upper. In other words, the
**   WHERE clause in the user's query might have been:
**
**       <tbl> MATCH <expr> AND rowid BETWEEN $iFirstRowid AND $iLastRowid
**
**   If the cursor iterates in descending order of rowid, iFirstRowid
**   is the upper limit (i.e. the "first" rowid visited) and iLastRowid
**   the lower.
*/
struct Fts5Cursor {
  sqlite3_vtab_cursor base;       /* Base class used by SQLite core */
  int ePlan;                      /* FTS5_PLAN_XXX value */
  int bDesc;                      /* True for "ORDER BY rowid DESC" queries */
  i64 iFirstRowid;                /* Return no rowids earlier than this */
  i64 iLastRowid;                 /* Return no rowids later than this */
  sqlite3_stmt *pStmt;            /* Statement used to read %_content */
  Fts5Expr *pExpr;                /* Expression for MATCH queries */
  Fts5Sorter *pSorter;            /* Sorter for "ORDER BY rank" queries */
  int csrflags;                   /* Mask of cursor flags (see below) */
  Fts5Cursor *pNext;              /* Next cursor in Fts5Cursor.pCsr list */
  i64 iSpecial;                   /* Result of special query */

  /* Variables used by auxiliary functions */
  i64 iCsrId;                     /* Cursor id */
  Fts5Auxiliary *pAux;            /* Currently executing extension function */
  Fts5Auxdata *pAuxdata;          /* First in linked list of saved aux-data */
  int *aColumnSize;               /* Values for xColumnSize() */

  /* Cache used by auxiliary functions xInst() and xInstCount() */
  int nInstCount;                 /* Number of phrase instances */
  int *aInst;                     /* 3 integers per phrase instance */
};

/*
** Bits that make up the "idxNum" parameter passed indirectly by 
** xBestIndex() to xFilter().
*/
#define FTS5_BI_MATCH        0x0001         /* <tbl> MATCH ? */
#define FTS5_BI_RANK         0x0002         /* rank MATCH ? */
#define FTS5_BI_ROWID_EQ     0x0004         /* rowid == ? */
#define FTS5_BI_ROWID_LE     0x0008         /* rowid <= ? */
#define FTS5_BI_ROWID_GE     0x0010         /* rowid >= ? */

#define FTS5_BI_ORDER_RANK   0x0020
#define FTS5_BI_ORDER_ROWID  0x0040
#define FTS5_BI_ORDER_DESC   0x0080

/*
** Values for Fts5Cursor.csrflags
*/
#define FTS5CSR_REQUIRE_CONTENT   0x01
#define FTS5CSR_REQUIRE_DOCSIZE   0x02
#define FTS5CSR_EOF               0x04
#define FTS5CSR_FREE_ZRANK        0x08
#define FTS5CSR_REQUIRE_RESEEK    0x10

#define BitFlagAllTest(x,y) (((x) & (y))==(y))
#define BitFlagTest(x,y)    (((x) & (y))!=0)

/*
** Constants for the largest and smallest possible 64-bit signed integers.
** These are copied from sqliteInt.h.
*/
#ifndef SQLITE_AMALGAMATION
# define LARGEST_INT64  (0xffffffff|(((i64)0x7fffffff)<<32))
# define SMALLEST_INT64 (((i64)-1) - LARGEST_INT64)
#endif

/*
** Macros to Set(), Clear() and Test() cursor flags.
*/
#define CsrFlagSet(pCsr, flag)   ((pCsr)->csrflags |= (flag))
#define CsrFlagClear(pCsr, flag) ((pCsr)->csrflags &= ~(flag))
#define CsrFlagTest(pCsr, flag)  ((pCsr)->csrflags & (flag))

  sqlite3_vtab **ppVtab,          /* OUT: New sqlite3_vtab object */
  char **pzErr                    /* OUT: sqlite3_malloc'd error message */
){
  return fts5InitVtab(1, db, pAux, argc, argv, ppVtab, pzErr);
}

/*
** The different query plans.
*/
#define FTS5_PLAN_SCAN           1       /* No usable constraint */
#define FTS5_PLAN_MATCH          2       /* (<tbl> MATCH ?) */
#define FTS5_PLAN_SORTED_MATCH   3       /* (<tbl> MATCH ? ORDER BY rank) */
#define FTS5_PLAN_ROWID          4       /* (rowid = ?) */
#define FTS5_PLAN_SOURCE         5       /* A source cursor for SORTED_MATCH */
#define FTS5_PLAN_SPECIAL        6       /* An internal query */


/*
** Implementation of the xBestIndex method for FTS5 tables. Within the 
** WHERE constraint, it searches for the following:
**
**   1. A MATCH constraint against the special column.
**   2. A MATCH constraint against the "rank" column.
**   3. An == constraint against the rowid column.
**   4. A < or <= constraint against the rowid column.
**   5. A > or >= constraint against the rowid column.
**
** Within the ORDER BY, either:
**
**   5. ORDER BY rank [ASC|DESC]
**   6. ORDER BY rowid [ASC|DESC]
**
** Costs are assigned as follows:
**

**  a) If an unusable MATCH operator is present in the WHERE clause, the

**     cost is unconditionally set to 1e50 (a really big number).
**
**  a) If a MATCH operator is present, the cost depends on the other
**     constraints also present. As follows:
**
**       * No other constraints:         cost=1000.0

**       * One rowid range constraint:   cost=750.0
**       * Both rowid range constraints: cost=500.0




**       * An == rowid constraint:       cost=100.0
**
**  b) Otherwise, if there is no MATCH:

**
**       * No other constraints:         cost=1000000.0
**       * One rowid range constraint:   cost=750000.0
**       * Both rowid range constraints: cost=250000.0
**       * An == rowid constraint:       cost=10.0
**
** Costs are not modified by the ORDER BY clause.
*/
static int fts5BestIndexMethod(sqlite3_vtab *pVTab, sqlite3_index_info *pInfo){
  Fts5Table *pTab = (Fts5Table*)pVTab;
  Fts5Config *pConfig = pTab->pConfig;
  int idxFlags = 0;               /* Parameter passed through to xFilter() */
  int bHasMatch;
  int iNext;
  int i;

  struct Constraint {
    int op;                       /* Mask against sqlite3_index_constraint.op */
    int fts5op;                   /* FTS5 mask for idxFlags */
    int iCol;                     /* 0==rowid, 1==tbl, 2==rank */
    int omit;                     /* True to omit this if found */
    int iConsIndex;               /* Index in pInfo->aConstraint[] */
  } aConstraint[] = {
    {SQLITE_INDEX_CONSTRAINT_MATCH, FTS5_BI_MATCH,    1, 1, -1},


    {SQLITE_INDEX_CONSTRAINT_MATCH, FTS5_BI_RANK,     2, 1, -1},
    {SQLITE_INDEX_CONSTRAINT_EQ,    FTS5_BI_ROWID_EQ, 0, 0, -1},

    {SQLITE_INDEX_CONSTRAINT_LT|SQLITE_INDEX_CONSTRAINT_LE, 
                                    FTS5_BI_ROWID_LE, 0, 0, -1},

    {SQLITE_INDEX_CONSTRAINT_GT|SQLITE_INDEX_CONSTRAINT_GE, 
                                    FTS5_BI_ROWID_GE, 0, 0, -1},
  };

  int aColMap[3];
  aColMap[0] = -1;
  aColMap[1] = pConfig->nCol;
  aColMap[2] = pConfig->nCol+1;

  /* Set idxFlags flags for all WHERE clause terms that will be used. */
  for(i=0; i<pInfo->nConstraint; i++){
    struct sqlite3_index_constraint *p = &pInfo->aConstraint[i];
    int j;
    for(j=0; j<sizeof(aConstraint)/sizeof(aConstraint[0]); j++){
      struct Constraint *pC = &aConstraint[j];
      if( p->iColumn==aColMap[pC->iCol] && p->op & pC->op ){
        if( p->usable ){
          pC->iConsIndex = i;
          idxFlags |= pC->fts5op;
        }else if( j==0 ){
          /* As there exists an unusable MATCH constraint this is an 
          ** unusable plan. Set a prohibitively high cost. */
          pInfo->estimatedCost = 1e50;
          return SQLITE_OK;
        }
      }
    }
  }

  /* Set idxFlags flags for the ORDER BY clause */
  if( pInfo->nOrderBy==1 ){
    int iSort = pInfo->aOrderBy[0].iColumn;
    if( iSort==(pConfig->nCol+1) && BitFlagTest(idxFlags, FTS5_BI_MATCH) ){
      idxFlags |= FTS5_BI_ORDER_RANK;

    }else if( iSort==-1 ){
      idxFlags |= FTS5_BI_ORDER_ROWID;
    }
    if( BitFlagTest(idxFlags, FTS5_BI_ORDER_RANK|FTS5_BI_ORDER_ROWID) ){
      pInfo->orderByConsumed = 1;
      if( pInfo->aOrderBy[0].desc ){
        idxFlags |= FTS5_BI_ORDER_DESC;
      }
    }


  }

  /* Calculate the estimated cost based on the flags set in idxFlags. */
  bHasMatch = BitFlagTest(idxFlags, FTS5_BI_MATCH);
  if( BitFlagTest(idxFlags, FTS5_BI_ROWID_EQ) ){
    pInfo->estimatedCost = bHasMatch ? 100.0 : 10.0;
  }else if( BitFlagAllTest(idxFlags, FTS5_BI_ROWID_LE|FTS5_BI_ROWID_GE) ){
    pInfo->estimatedCost = bHasMatch ? 500.0 : 250000.0;
  }else if( BitFlagTest(idxFlags, FTS5_BI_ROWID_LE|FTS5_BI_ROWID_GE) ){
    pInfo->estimatedCost = bHasMatch ? 750.0 : 750000.0;
  }else{
    pInfo->estimatedCost = bHasMatch ? 1000.0 : 1000000.0;
  }



  /* Assign argvIndex values to each constraint in use. */
  iNext = 1;
  for(i=0; i<sizeof(aConstraint)/sizeof(aConstraint[0]); i++){
    struct Constraint *pC = &aConstraint[i];
    if( pC->iConsIndex>=0 ){
      pInfo->aConstraintUsage[pC->iConsIndex].argvIndex = iNext++;
      pInfo->aConstraintUsage[pC->iConsIndex].omit = pC->omit;
    }
  }

  pInfo->idxNum = idxFlags;
  return SQLITE_OK;
}

/*
** Implementation of xOpen method.
*/
static int fts5OpenMethod(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCsr){

  }else{
    rc = SQLITE_NOMEM;
  }
  *ppCsr = (sqlite3_vtab_cursor*)pCsr;
  return rc;
}

static int fts5StmtType(Fts5Cursor *pCsr){
  if( pCsr->ePlan==FTS5_PLAN_SCAN ){
    return (pCsr->bDesc) ? FTS5_STMT_SCAN_DESC : FTS5_STMT_SCAN_ASC;
  }
  return FTS5_STMT_LOOKUP;
}

/*
** This function is called after the cursor passed as the only argument
** is moved to point at a different row. It clears all cached data 

    Fts5Cursor *pCsr = (Fts5Cursor*)pCursor;
    Fts5Cursor **pp;
    Fts5Auxdata *pData;
    Fts5Auxdata *pNext;

    fts5CsrNewrow(pCsr);
    if( pCsr->pStmt ){
      int eStmt = fts5StmtType(pCsr);
      sqlite3Fts5StorageStmtRelease(pTab->pStorage, eStmt, pCsr->pStmt);
    }
    if( pCsr->pSorter ){
      Fts5Sorter *pSorter = pCsr->pSorter;
      sqlite3_finalize(pSorter->pStmt);
      sqlite3_free(pSorter);
    }

    if( pCsr->ePlan!=FTS5_PLAN_SOURCE ){
      sqlite3Fts5ExprFree(pCsr->pExpr);
    }

    for(pData=pCsr->pAuxdata; pData; pData=pNext){
      pNext = pData->pNext;
      if( pData->xDelete ) pData->xDelete(pData->pPtr);
      sqlite3_free(pData);

/*
** Set the FTS5CSR_REQUIRE_RESEEK flag on all FTS5_PLAN_MATCH cursors 
** open on table pTab.
*/
static void fts5TripCursors(Fts5Table *pTab){
  Fts5Cursor *pCsr;
  for(pCsr=pTab->pGlobal->pCsr; pCsr; pCsr=pCsr->pNext){
    if( pCsr->ePlan==FTS5_PLAN_MATCH
     && pCsr->base.pVtab==(sqlite3_vtab*)pTab 
    ){
      CsrFlagSet(pCsr, FTS5CSR_REQUIRE_RESEEK);
    }
  }
}

** error code if an error occurred.
*/
static int fts5CursorReseek(Fts5Cursor *pCsr, int *pbSkip){
  int rc = SQLITE_OK;
  assert( *pbSkip==0 );
  if( CsrFlagTest(pCsr, FTS5CSR_REQUIRE_RESEEK) ){
    Fts5Table *pTab = (Fts5Table*)(pCsr->base.pVtab);
    int bDesc = pCsr->bDesc;
    i64 iRowid = sqlite3Fts5ExprRowid(pCsr->pExpr);

    rc = sqlite3Fts5ExprFirst(pCsr->pExpr, pTab->pIndex, iRowid, bDesc);

    if( rc==SQLITE_OK && iRowid!=sqlite3Fts5ExprRowid(pCsr->pExpr) ){


      *pbSkip = 1;



    }

    CsrFlagClear(pCsr, FTS5CSR_REQUIRE_RESEEK);
    fts5CsrNewrow(pCsr);
    if( sqlite3Fts5ExprEof(pCsr->pExpr) ){
      CsrFlagSet(pCsr, FTS5CSR_EOF);
    }

**
** Return SQLITE_OK if nothing goes wrong.  SQLITE_OK is returned
** even if we reach end-of-file.  The fts5EofMethod() will be called
** subsequently to determine whether or not an EOF was hit.
*/
static int fts5NextMethod(sqlite3_vtab_cursor *pCursor){
  Fts5Cursor *pCsr = (Fts5Cursor*)pCursor;
  int ePlan = pCsr->ePlan;
  int bSkip = 0;
  int rc;

  if( (rc = fts5CursorReseek(pCsr, &bSkip)) || bSkip ) return rc;

  switch( ePlan ){
    case FTS5_PLAN_MATCH:
    case FTS5_PLAN_SOURCE:
      rc = sqlite3Fts5ExprNext(pCsr->pExpr, pCsr->iLastRowid);
      if( sqlite3Fts5ExprEof(pCsr->pExpr) ){
        CsrFlagSet(pCsr, FTS5CSR_EOF);
      }
      fts5CsrNewrow(pCsr);
      break;

    case FTS5_PLAN_SPECIAL: {

  }

  return rc;
}

static int fts5CursorFirst(Fts5Table *pTab, Fts5Cursor *pCsr, int bDesc){
  int rc;
  Fts5Expr *pExpr = pCsr->pExpr;
  rc = sqlite3Fts5ExprFirst(pExpr, pTab->pIndex, pCsr->iFirstRowid, bDesc);
  if( sqlite3Fts5ExprEof(pExpr) ){
    CsrFlagSet(pCsr, FTS5CSR_EOF);
  }
  fts5CsrNewrow(pCsr);
  return rc;
}

/*

  const char *z = zQuery;         /* Special query text */
  int n;                          /* Number of bytes in text at z */

  while( z[0]==' ' ) z++;
  for(n=0; z[n] && z[n]!=' '; n++);

  assert( pTab->base.zErrMsg==0 );
  pCsr->ePlan = FTS5_PLAN_SPECIAL;

  if( 0==sqlite3_strnicmp("reads", z, n) ){
    pCsr->iSpecial = sqlite3Fts5IndexReads(pTab->pIndex);
  }
  else if( 0==sqlite3_strnicmp("id", z, n) ){
    pCsr->iSpecial = pCsr->iCsrId;
  }

    }else{
      pCsr->zRank = (char*)FTS5_DEFAULT_RANK;
      pCsr->zRankArgs = 0;
    }
  }
  return rc;
}

static i64 fts5GetRowidLimit(sqlite3_value *pVal, i64 iDefault){
  if( pVal ){
    int eType = sqlite3_value_numeric_type(pVal);
    if( eType==SQLITE_INTEGER ){
      return sqlite3_value_int64(pVal);
    }
  }
  return iDefault;
}

/*
** This is the xFilter interface for the virtual table.  See
** the virtual table xFilter method documentation for additional
** information.
** 
** There are three possible query strategies:

  int idxNum,                     /* Strategy index */
  const char *idxStr,             /* Unused */
  int nVal,                       /* Number of elements in apVal */
  sqlite3_value **apVal           /* Arguments for the indexing scheme */
){
  Fts5Table *pTab = (Fts5Table*)(pCursor->pVtab);
  Fts5Cursor *pCsr = (Fts5Cursor*)pCursor;

  int rc = SQLITE_OK;             /* Error code */
  int iVal = 0;                   /* Counter for apVal[] */
  int bDesc;                      /* True if ORDER BY [rank|rowid] DESC */
  int bOrderByRank;               /* True if ORDER BY rank */
  sqlite3_value *pMatch = 0;      /* <tbl> MATCH ? expression (or NULL) */
  sqlite3_value *pRank = 0;       /* rank MATCH ? expression (or NULL) */
  sqlite3_value *pRowidEq = 0;    /* rowid = ? expression (or NULL) */
  sqlite3_value *pRowidLe = 0;    /* rowid <= ? expression (or NULL) */
  sqlite3_value *pRowidGe = 0;    /* rowid >= ? expression (or NULL) */
  char **pzErrmsg = pTab->pConfig->pzErrmsg;





  assert( pCsr->pStmt==0 );
  assert( pCsr->pExpr==0 );
  assert( pCsr->csrflags==0 );
  assert( pCsr->pRank==0 );
  assert( pCsr->zRank==0 );
  assert( pCsr->zRankArgs==0 );

  assert( pzErrmsg==0 || pzErrmsg==&pTab->base.zErrMsg );
  pTab->pConfig->pzErrmsg = &pTab->base.zErrMsg;

  /* Decode the arguments passed through to this function.
  **
  ** Note: The following set of if(...) statements must be in the same
  ** order as the corresponding entries in the struct at the top of
  ** fts5BestIndexMethod().  */
  if( BitFlagTest(idxNum, FTS5_BI_MATCH) ) pMatch = apVal[iVal++];
  if( BitFlagTest(idxNum, FTS5_BI_RANK) ) pRank = apVal[iVal++];
  if( BitFlagTest(idxNum, FTS5_BI_ROWID_EQ) ) pRowidEq = apVal[iVal++];
  if( BitFlagTest(idxNum, FTS5_BI_ROWID_LE) ) pRowidLe = apVal[iVal++];
  if( BitFlagTest(idxNum, FTS5_BI_ROWID_GE) ) pRowidGe = apVal[iVal++];
  assert( iVal==nVal );
  bOrderByRank = ((idxNum & FTS5_BI_ORDER_RANK) ? 1 : 0);
  pCsr->bDesc = bDesc = ((idxNum & FTS5_BI_ORDER_DESC) ? 1 : 0);

  /* Set the cursor upper and lower rowid limits. Only some strategies 
  ** actually use them. This is ok, as the xBestIndex() method leaves the
  ** sqlite3_index_constraint.omit flag clear for range constraints
  ** on the rowid field.  */
  if( pRowidEq ){
    pRowidLe = pRowidGe = pRowidEq;
  }
  if( bDesc ){
    pCsr->iFirstRowid = fts5GetRowidLimit(pRowidLe, LARGEST_INT64);
    pCsr->iLastRowid = fts5GetRowidLimit(pRowidGe, SMALLEST_INT64);
  }else{
    pCsr->iLastRowid = fts5GetRowidLimit(pRowidLe, LARGEST_INT64);
    pCsr->iFirstRowid = fts5GetRowidLimit(pRowidGe, SMALLEST_INT64);
  }

  if( pTab->pSortCsr ){
    /* If pSortCsr is non-NULL, then this call is being made as part of 
    ** processing for a "... MATCH <expr> ORDER BY rank" query (ePlan is
    ** set to FTS5_PLAN_SORTED_MATCH). pSortCsr is the cursor that will
    ** return results to the user for this query. The current cursor 
    ** (pCursor) is used to execute the query issued by function 
    ** fts5CursorFirstSorted() above.  */
    assert( pRowidEq==0 && pRowidLe==0 && pRowidGe==0 && pRank==0 );
    assert( nVal==0 && pMatch==0 && bOrderByRank==0 && bDesc==0 );
    assert( pCsr->iLastRowid==LARGEST_INT64 );
    assert( pCsr->iFirstRowid==SMALLEST_INT64 );
    pCsr->ePlan = FTS5_PLAN_SOURCE;
    pCsr->pExpr = pTab->pSortCsr->pExpr;
    rc = fts5CursorFirst(pTab, pCsr, bDesc);
  }else if( pMatch ){



    const char *zExpr = (const char*)sqlite3_value_text(apVal[0]);

    rc = fts5CursorParseRank(pTab->pConfig, pCsr, pRank);
    if( rc==SQLITE_OK ){
      if( zExpr[0]=='*' ){
        /* The user has issued a query of the form "MATCH '*...'". This
        ** indicates that the MATCH expression is not a full text query,
        ** but a request for an internal parameter.  */
        rc = fts5SpecialMatch(pTab, pCsr, &zExpr[1]);
      }else{
        char **pzErr = &pTab->base.zErrMsg;
        rc = sqlite3Fts5ExprNew(pTab->pConfig, zExpr, &pCsr->pExpr, pzErr);
        if( rc==SQLITE_OK ){
          if( bOrderByRank ){
            pCsr->ePlan = FTS5_PLAN_SORTED_MATCH;
            rc = fts5CursorFirstSorted(pTab, pCsr, bDesc);
          }else{
            pCsr->ePlan = FTS5_PLAN_MATCH;
            rc = fts5CursorFirst(pTab, pCsr, bDesc);
          }
        }
      }
    }
  }else{
    /* This is either a full-table scan (ePlan==FTS5_PLAN_SCAN) or a lookup
    ** by rowid (ePlan==FTS5_PLAN_ROWID).  */

    pCsr->ePlan = (pRowidEq ? FTS5_PLAN_ROWID : FTS5_PLAN_SCAN);
    rc = sqlite3Fts5StorageStmt(
        pTab->pStorage, fts5StmtType(pCsr), &pCsr->pStmt, &pTab->base.zErrMsg
    );
    if( rc==SQLITE_OK ){
      if( pCsr->ePlan==FTS5_PLAN_ROWID ){
        sqlite3_bind_value(pCsr->pStmt, 1, apVal[0]);
      }
      rc = fts5NextMethod(pCursor);

    }
  }

  pTab->pConfig->pzErrmsg = pzErrmsg;
  return rc;
}

/* 
** This is the xEof method of the virtual table. SQLite calls this 
** routine to find out if it has reached the end of a result set.
*/
static int fts5EofMethod(sqlite3_vtab_cursor *pCursor){
  Fts5Cursor *pCsr = (Fts5Cursor*)pCursor;
  return (CsrFlagTest(pCsr, FTS5CSR_EOF) ? 1 : 0);
}

/*
** Return the rowid that the cursor currently points to.
*/
static i64 fts5CursorRowid(Fts5Cursor *pCsr){
  assert( pCsr->ePlan==FTS5_PLAN_MATCH 
       || pCsr->ePlan==FTS5_PLAN_SORTED_MATCH 
       || pCsr->ePlan==FTS5_PLAN_SOURCE 
  );
  if( pCsr->pSorter ){
    return pCsr->pSorter->iRowid;
  }else{
    return sqlite3Fts5ExprRowid(pCsr->pExpr);
  }
}

/* 
** This is the xRowid method. The SQLite core calls this routine to
** retrieve the rowid for the current row of the result set. fts5
** exposes %_content.docid as the rowid for the virtual table. The
** rowid should be written to *pRowid.
*/
static int fts5RowidMethod(sqlite3_vtab_cursor *pCursor, sqlite_int64 *pRowid){
  Fts5Cursor *pCsr = (Fts5Cursor*)pCursor;
  int ePlan = pCsr->ePlan;
  
  assert( CsrFlagTest(pCsr, FTS5CSR_EOF)==0 );
  switch( ePlan ){
    case FTS5_PLAN_SPECIAL:
      *pRowid = 0;
      break;

*/
static int fts5SeekCursor(Fts5Cursor *pCsr){
  int rc = SQLITE_OK;

  /* If the cursor does not yet have a statement handle, obtain one now. */ 
  if( pCsr->pStmt==0 ){
    Fts5Table *pTab = (Fts5Table*)(pCsr->base.pVtab);
    int eStmt = fts5StmtType(pCsr);
    rc = sqlite3Fts5StorageStmt(
        pTab->pStorage, eStmt, &pCsr->pStmt, &pTab->base.zErrMsg
    );
    assert( CsrFlagTest(pCsr, FTS5CSR_REQUIRE_CONTENT) );
  }

  if( rc==SQLITE_OK && CsrFlagTest(pCsr, FTS5CSR_REQUIRE_CONTENT) ){

  Fts5Table *pTab = (Fts5Table*)(pCsr->base.pVtab);
  int rc;
  Fts5Cursor *pNew = 0;

  rc = fts5OpenMethod(pCsr->base.pVtab, (sqlite3_vtab_cursor**)&pNew);
  if( rc==SQLITE_OK ){
    Fts5Config *pConf = pTab->pConfig;
    pNew->ePlan = FTS5_PLAN_MATCH;
    pNew->iFirstRowid = SMALLEST_INT64;
    pNew->iLastRowid = LARGEST_INT64;
    pNew->base.pVtab = (sqlite3_vtab*)pTab;
    rc = sqlite3Fts5ExprPhraseExpr(pConf, pCsr->pExpr, iPhrase, &pNew->pExpr);
  }

  if( rc==SQLITE_OK ){
    for(rc = fts5CursorFirst(pTab, pNew, 0);
        rc==SQLITE_OK && CsrFlagTest(pNew, FTS5CSR_EOF)==0;

  Fts5Table *pTab = (Fts5Table*)(pCursor->pVtab);
  Fts5Config *pConfig = pTab->pConfig;
  Fts5Cursor *pCsr = (Fts5Cursor*)pCursor;
  int rc = SQLITE_OK;
  
  assert( CsrFlagTest(pCsr, FTS5CSR_EOF)==0 );

  if( pCsr->ePlan==FTS5_PLAN_SPECIAL ){
    if( iCol==pConfig->nCol ){
      sqlite3_result_int64(pCtx, pCsr->iSpecial);
    }
  }else

  if( iCol==pConfig->nCol ){
    /* User is requesting the value of the special column with the same name
    ** as the table. Return the cursor integer id number. This value is only
    ** useful in that it may be passed as the first argument to an FTS5
    ** auxiliary function.  */
    sqlite3_result_int64(pCtx, pCsr->iCsrId);
  }else if( iCol==pConfig->nCol+1 ){

    /* The value of the "rank" column. */
    if( pCsr->ePlan==FTS5_PLAN_SOURCE ){
      fts5PoslistBlob(pCtx, pCsr);
    }else if( 
        pCsr->ePlan==FTS5_PLAN_MATCH
     || pCsr->ePlan==FTS5_PLAN_SORTED_MATCH
    ){
      if( pCsr->pRank || SQLITE_OK==(rc = fts5FindRankFunction(pCsr)) ){
        fts5ApiInvoke(pCsr->pRank, pCsr, pCtx, pCsr->nRankArg, pCsr->apRankArg);
      }
    }
  }else if( !fts5IsContentless(pTab) ){
    rc = fts5SeekCursor(pCsr);

**     rc==SQLITE_OK && 0==sqlite3Fts5ExprEof(pExpr);
**     rc = sqlite3Fts5ExprNext(pExpr)
** ){
**   // The document with rowid iRowid matches the expression!
**   i64 iRowid = sqlite3Fts5ExprRowid(pExpr);
** }
*/
int sqlite3Fts5ExprFirst(Fts5Expr*, Fts5Index *pIdx, i64 iMin, int bDesc);
int sqlite3Fts5ExprNext(Fts5Expr*, i64 iMax);
int sqlite3Fts5ExprEof(Fts5Expr*);
i64 sqlite3Fts5ExprRowid(Fts5Expr*);

void sqlite3Fts5ExprFree(Fts5Expr*);

/* Called during startup to register a UDF with SQLite */
int sqlite3Fts5ExprInit(Fts5Global*, sqlite3*);

  }
  return rc;
}


/*
** Begin iterating through the set of documents in index pIdx matched by
** the MATCH expression passed as the first argument. If the "bDesc" 
** parameter is passed a non-zero value, iteration is in descending rowid 
** order. Or, if it is zero, in ascending order.
**
** If iterating in ascending rowid order (bDesc==0), the first document
** visited is that with the smallest rowid that is larger than or equal
** to parameter iFirst. Or, if iterating in ascending order (bDesc==1),
** then the first document visited must have a rowid smaller than or
** equal to iFirst.
**
** Return SQLITE_OK if successful, or an SQLite error code otherwise. It
** is not considered an error if the query does not match any documents.
*/
int sqlite3Fts5ExprFirst(Fts5Expr *p, Fts5Index *pIdx, i64 iFirst, int bDesc){
  Fts5ExprNode *pRoot = p->pRoot;
  int rc = SQLITE_OK;
  if( pRoot ){
    p->pIndex = pIdx;
    p->bDesc = bDesc;
    rc = fts5ExprNodeFirst(p, pRoot);

    /* If not at EOF but the current rowid occurs earlier than iFirst in
    ** the iteration order, move to document iFirst or later. */
    if( pRoot->bEof==0 && fts5RowidCmp(p, pRoot->iRowid, iFirst)<0 ){
      rc = fts5ExprNodeNext(p, pRoot, 1, iFirst);
    }

    /* If the iterator is not at a real match, skip forward until it is. */
    while( pRoot->bNomatch && rc==SQLITE_OK && pRoot->bEof==0 ){
      rc = fts5ExprNodeNext(p, pRoot, 0, 0);
    }
  }
  return rc;
}

/*
** Move to the next document 
**
** Return SQLITE_OK if successful, or an SQLite error code otherwise. It
** is not considered an error if the query does not match any documents.
*/
int sqlite3Fts5ExprNext(Fts5Expr *p, i64 iLast){
  int rc;
  Fts5ExprNode *pRoot = p->pRoot;
  do {
    rc = fts5ExprNodeNext(p, pRoot, 0, 0);
  }while( pRoot->bNomatch && pRoot->bEof==0 && rc==SQLITE_OK );
  if( fts5RowidCmp(p, pRoot->iRowid, iLast)>0 ){
    pRoot->bEof = 1;
  }
  return rc;
}

int sqlite3Fts5ExprEof(Fts5Expr *p){
  return (p->pRoot==0 || p->pRoot->bEof);
}

    puts -nonewline "(n=$n nReadX=$nReadX)"
    expr {$n < ($nReadX / 8)}
  } {1}

  do_execsql_test 1.6.$tn.3 $q [lsort -int -incr $res]
  do_execsql_test 1.6.$tn.4 "$q ORDER BY rowid DESC" [lsort -int -decr $res]
}

#-------------------------------------------------------------------------
# Now test that adding range constraints on the rowid field reduces the
# number of pages loaded from disk.
#
foreach {tn fraction tail cnt} {
  1 0.6 {rowid > 5000} 5000
  2 0.2 {rowid > 9000} 1000
  3 0.2 {rowid < 1000}  999
  4 0.2 {rowid BETWEEN 4000 AND 5000}  1001
  5 0.6 {rowid >= 5000} 5001
  6 0.2 {rowid >= 9000} 1001
  7 0.2 {rowid <= 1000} 1000
  8 0.6 {rowid > '5000'} 5000
  9 0.2 {rowid > '9000'} 1000
  10 0.1 {rowid = 444} 1
} {
  set q "SELECT rowid FROM t1 WHERE t1 MATCH 'x' AND $tail"
  set n [execsql_reads $q]
  set ret [llength [execsql $q]]

  do_test "1.7.$tn.asc.(n=$n ret=$ret)" {
    expr {$n < ($fraction*$nReadX) && $ret==$cnt}
  } {1}

  set q "SELECT rowid FROM t1 WHERE t1 MATCH 'x' AND $tail ORDER BY rowid DESC"
  set n [execsql_reads $q]
  set ret [llength [execsql $q]]
  do_test "1.7.$tn.desc.(n=$n ret=$ret)" {
    expr {$n < 2*$fraction*$nReadX && $ret==$cnt}
  } {1}
}

do_execsql_test 1.8.1 {
  SELECT count(*) FROM t1 WHERE t1 MATCH 'x' AND +rowid < 'text';
} {10000}
do_execsql_test 1.8.2 {
  SELECT count(*) FROM t1 WHERE t1 MATCH 'x' AND rowid < 'text';
} {10000}


#db eval {SELECT rowid, fts5_decode(rowid, block) aS r FROM t1_data} {puts $r}

finish_test

  CREATE VIRTUAL TABLE f1 USING fts5(ff);
}

do_eqp_test 1.1 {
  SELECT * FROM t1, f1 WHERE f1 MATCH t1.x
} {
  0 0 0 {SCAN TABLE t1} 
  0 1 1 {SCAN TABLE f1 VIRTUAL TABLE INDEX 1:}
}

do_eqp_test 1.2 {
  SELECT * FROM t1, f1 WHERE f1 > t1.x
} {
  0 0 1 {SCAN TABLE f1 VIRTUAL TABLE INDEX 0:}
  0 1 0 {SCAN TABLE t1} 
}

do_eqp_test 1.3 {
  SELECT * FROM f1 WHERE f1 MATCH ? ORDER BY ff
} {
  0 0 0 {SCAN TABLE f1 VIRTUAL TABLE INDEX 1:}
  0 0 0 {USE TEMP B-TREE FOR ORDER BY}
}

do_eqp_test 1.4 {
  SELECT * FROM f1 ORDER BY rank
} {
  0 0 0 {SCAN TABLE f1 VIRTUAL TABLE INDEX 0:}
  0 0 0 {USE TEMP B-TREE FOR ORDER BY}
}

do_eqp_test 1.5 {
  SELECT * FROM f1 WHERE rank MATCH ?
} {
  0 0 0 {SCAN TABLE f1 VIRTUAL TABLE INDEX 2:}
}




finish_test