SQLite

**
**   SELECT rowid, <fts> FROM <fts> ORDER BY +rank;
**
*/
struct Fts5Sorter {
  sqlite3_stmt *pStmt;
  i64 iRowid;                     /* Current rowid */
  const u8 *aPoslist;             /* Position lists for current row */
  int nIdx;                       /* Number of entries in aIdx[] */
  int aIdx[0];                    /* Offsets into aPoslist for current row */
};

/*
** Virtual-table cursor object.
*/

  int rc;

  rc = sqlite3_step(pSorter->pStmt);
  if( rc==SQLITE_DONE ){
    rc = SQLITE_OK;
    CsrFlagSet(pCsr, FTS5CSR_EOF);
  }else if( rc==SQLITE_ROW ){
    const u8 *a;
    const u8 *aBlob;
    int nBlob;
    int i;
    rc = SQLITE_OK;

    pSorter->iRowid = sqlite3_column_int64(pSorter->pStmt, 0);
    nBlob = sqlite3_column_bytes(pSorter->pStmt, 1);
    aBlob = a = sqlite3_column_blob(pSorter->pStmt, 1);

    for(i=0; i<(pSorter->nIdx-1); i++){
      a += getVarint32(a, pSorter->aIdx[i]);
    }
    pSorter->aIdx[i] = &aBlob[nBlob] - a;
    pSorter->aPoslist = a;
    CsrFlagSet(pCsr, FTS5CSR_REQUIRE_CONTENT | FTS5CSR_REQUIRE_DOCSIZE );
  }

  return rc;
}

/*
** Advance the cursor to the next row in the table that matches the 

  
  nPhrase = sqlite3Fts5ExprPhraseCount(pCsr->pExpr);
  nByte = sizeof(Fts5Sorter) + sizeof(int) * nPhrase;
  pSorter = (Fts5Sorter*)sqlite3_malloc(nByte);
  if( pSorter==0 ) return SQLITE_NOMEM;
  memset(pSorter, 0, nByte);

  zSql = sqlite3_mprintf("SELECT rowid, %s FROM %Q.%Q ORDER BY +%s %s",
      pConfig->zName, pConfig->zDb, pConfig->zName, FTS5_RANK_NAME,
      bAsc ? "ASC" : "DESC"
  );
  if( zSql==0 ){
    rc = SQLITE_NOMEM;
  }else{
    rc = sqlite3_prepare_v2(pConfig->db, zSql, -1, &pSorter->pStmt, 0);

** 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( FTS5_PLAN(pCsr->idxNum)==FTS5_PLAN_MATCH 
       || FTS5_PLAN(pCsr->idxNum)==FTS5_PLAN_SORTED_MATCH 
       || FTS5_PLAN(pCsr->idxNum)==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 = FTS5_PLAN(pCsr->idxNum);
  
  assert( CsrFlagTest(pCsr, FTS5CSR_EOF)==0 );
  switch( ePlan ){
    case FTS5_PLAN_SOURCE:
    case FTS5_PLAN_MATCH:



    case FTS5_PLAN_SORTED_MATCH:
      *pRowid = fts5CursorRowid(pCsr);
      break;

    default:
      *pRowid = sqlite3_column_int64(pCsr->pStmt, 0);
      break;
  }

  return SQLITE_OK;
}

/*
** If the cursor requires seeking (bSeekRequired flag is set), seek it.
** Return SQLITE_OK if no error occurs, or an SQLite error code otherwise.
*/
static int fts5SeekCursor(Fts5Cursor *pCsr){
  int rc = SQLITE_OK;
  if( CsrFlagTest(pCsr, FTS5CSR_REQUIRE_CONTENT) ){
    assert( pCsr->pExpr );
    sqlite3_reset(pCsr->pStmt);
    sqlite3_bind_int64(pCsr->pStmt, 1, fts5CursorRowid(pCsr));
    rc = sqlite3_step(pCsr->pStmt);
    if( rc==SQLITE_ROW ){
      rc = SQLITE_OK;
      CsrFlagClear(pCsr, FTS5CSR_REQUIRE_CONTENT);
    }else{
      rc = sqlite3_reset(pCsr->pStmt);
      if( rc==SQLITE_OK ){

static int fts5ApiPhraseSize(Fts5Context *pCtx, int iPhrase){
  Fts5Cursor *pCsr = (Fts5Cursor*)pCtx;
  return sqlite3Fts5ExprPhraseSize(pCsr->pExpr, iPhrase);
}

static sqlite3_int64 fts5ApiRowid(Fts5Context *pCtx){
  Fts5Cursor *pCsr = (Fts5Cursor*)pCtx;
  return fts5CursorRowid((Fts5Cursor*)pCtx);
}

static int fts5ApiColumnText(
  Fts5Context *pCtx, 
  int iCol, 
  const char **pz, 
  int *pn

static int fts5ApiColumnSize(Fts5Context *pCtx, int iCol, int *pnToken){
  Fts5Cursor *pCsr = (Fts5Cursor*)pCtx;
  Fts5Table *pTab = (Fts5Table*)(pCsr->base.pVtab);
  int rc = SQLITE_OK;

  if( CsrFlagTest(pCsr, FTS5CSR_REQUIRE_DOCSIZE) ){
    i64 iRowid = fts5CursorRowid(pCsr);
    rc = sqlite3Fts5StorageDocsize(pTab->pStorage, iRowid, pCsr->aColumnSize);
  }
  if( iCol>=0 && iCol<pTab->pConfig->nCol ){
    *pnToken = pCsr->aColumnSize[iCol];
  }else{
    *pnToken = 0;
  }
  return rc;
}

static int fts5ApiPoslist(
  Fts5Context *pCtx, 
  int iPhrase, 
  int *pi, 
  i64 *piPos 
){
  Fts5Cursor *pCsr = (Fts5Cursor*)pCtx;
  const u8 *a; int n;             /* Poslist for phrase iPhrase */
  if( pCsr->pSorter ){
    Fts5Sorter *pSorter = pCsr->pSorter;
    int i1 = (iPhrase ? 0 : pSorter->aIdx[iPhrase-1]);
    n = pSorter->aIdx[iPhrase] - i1;
    a = &pSorter->aPoslist[i1];
  }else{
    n = sqlite3Fts5ExprPoslist(pCsr->pExpr, iPhrase, &a);
  }
  return sqlite3Fts5PoslistNext64(a, n, pi, piPos);
}

static int fts5ApiSetAuxdata(
  Fts5Context *pCtx,              /* Fts5 context */
  void *pPtr,                     /* Pointer to save as auxdata */
  void(*xDelete)(void*)           /* Destructor for pPtr (or NULL) */

  if( pCsr==0 ){
    char *zErr = sqlite3_mprintf("no such cursor: %lld", iCsrId);
    sqlite3_result_error(context, zErr, -1);
  }else{
    fts5ApiInvoke(pAux, pCsr, context, argc-1, &argv[1]);
  }
}

static int fts5PoslistBlob(sqlite3_context *pCtx, Fts5Cursor *pCsr){
  int i;
  int rc = SQLITE_OK;
  int nPhrase = sqlite3Fts5ExprPhraseCount(pCsr->pExpr);
  Fts5Buffer val;
  int iOff = 0;

  memset(&val, 0, sizeof(Fts5Buffer));
  for(i=0; i<nPhrase; i++){
    const u8 *dummy;
    if( i ) sqlite3Fts5BufferAppendVarint(&rc, &val, iOff);
    iOff += sqlite3Fts5ExprPoslist(pCsr->pExpr, i, &dummy);
  }

  for(i=0; i<nPhrase; i++){
    const u8 *pPoslist;
    int nPoslist;
    nPoslist = sqlite3Fts5ExprPoslist(pCsr->pExpr, i, &pPoslist);
    sqlite3Fts5BufferAppendBlob(&rc, &val, nPoslist, pPoslist);
  }

  sqlite3_result_blob(pCtx, val.p, val.n, sqlite3_free);
  return rc;
}

/* 
** This is the xColumn method, called by SQLite to request a value from
** the row that the supplied cursor currently points to.
*/
static int fts5ColumnMethod(
  sqlite3_vtab_cursor *pCursor,   /* Cursor to retrieve value from */
  sqlite3_context *pCtx,          /* Context for sqlite3_result_xxx() calls */
  int iCol                        /* Index of column to read value from */
){
  Fts5Config *pConfig = ((Fts5Table*)(pCursor->pVtab))->pConfig;
  Fts5Cursor *pCsr = (Fts5Cursor*)pCursor;
  int rc = SQLITE_OK;
  
  assert( CsrFlagTest(pCsr, FTS5CSR_EOF)==0 );

  if( iCol==pConfig->nCol ){
    if( FTS5_PLAN(pCsr->idxNum)==FTS5_PLAN_SOURCE ){
      fts5PoslistBlob(pCtx, pCsr);
    }else{
      /* 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);
    }

  } [list $res]

  do_execsql_test $tn.2 {
    DELETE FROM t1;
    INSERT INTO t1 VALUES(NULL, $v1);
    SELECT snippet(t1, '[', ']', '...', 7) FROM t1 WHERE t1 MATCH $v2;
  } [list $res]

  do_execsql_test $tn.3 {
    DELETE FROM t1;
    INSERT INTO t1 VALUES($v1, NULL);
    SELECT snippet(t1, '[', ']', '...', 7) FROM t1 WHERE t1 MATCH $v2
    ORDER BY rank DESC;
  } [list $res]


}


foreach {tn doc res} {

  1.1 {X o o o o o o} {[X] o o o o o o}