SQLite

** This function returns a copy of the identifier enclosed in backtick 
** quotes.
*/
static char *fts5EscapeName(int *pRc, const char *z){
  char *pRet = 0;
  if( *pRc==SQLITE_OK ){
    int n = strlen(z);
    pRet = (char*)sqlite3_malloc(2 + 2*n + 1);
    if( pRet==0 ){
      *pRc = SQLITE_NOMEM;
    }else{
      int i;
      char *p = pRet;
      *p++ = '`';
      for(i=0; i<n; i++){
        if( z[i]=='`' ) *p++ = '`';
        *p++ = z[i];
      }
      *p++ = '`';
      *p++ = '\0';
    }

**
** aFirst[1] contains the index in aSeg[] of the iterator that points to
** the smallest key overall. aFirst[0] is unused. 
*/
struct Fts5MultiSegIter {
  int nSeg;                       /* Size of aSeg[] array */
  int bRev;                       /* True to iterate in reverse order */
  int bSkipEmpty;                 /* True to skip deleted entries */
  Fts5SegIter *aSeg;              /* Array of segment iterators */
  u16 *aFirst;                    /* Current merge state (see above) */
};

/*
** Object for iterating through a single segment, visiting each term/docid
** pair in the segment.

    }
  }

  if( pIter->pLeaf ){
    fts5SegIterReverseInitPage(p, pIter);
  }
}

/*
** Return true if the iterator passed as the second argument currently
** points to a delete marker. A delete marker is an entry with a 0 byte
** position-list.
*/
static int fts5SegIterIsDelete(
  Fts5Index *p,                   /* FTS5 backend object */
  Fts5SegIter *pIter              /* Iterator to advance */
){
  int bRet = 0;
  Fts5Data *pLeaf = pIter->pLeaf;
  if( p->rc==SQLITE_OK && pLeaf ){
    if( pIter->iLeafOffset<pLeaf->n ){
      bRet = (pLeaf->p[pIter->iLeafOffset]==0x00);
    }else{
      Fts5Data *pNew = fts5DataRead(p, FTS5_SEGMENT_ROWID(
            pIter->iIdx, pIter->pSeg->iSegid, 0, pIter->iLeafPgno
      ));
      if( pNew ){
        bRet = (pNew->p[4]==0x00);
        fts5DataRelease(pNew);
      }
    }
  }
  return bRet;
}

/*
** Advance iterator pIter to the next entry. 
**
** If an error occurs, Fts5Index.rc is set to an appropriate error code. It 
** is not considered an error if the iterator reaches EOF. If an error has 
** already occurred when this function is called, it is a no-op.

static void fts5MultiIterNext(
  Fts5Index *p, 
  Fts5MultiSegIter *pIter,
  int bFrom,                      /* True if argument iFrom is valid */
  i64 iFrom                       /* Advance at least as far as this */
){
  if( p->rc==SQLITE_OK ){
    int bUseFrom = bFrom;
    do {
      int iFirst = pIter->aFirst[1];
      Fts5SegIter *pSeg = &pIter->aSeg[iFirst];
      if( bUseFrom && pSeg->pDlidx ){
        fts5SegIterNextFrom(p, pSeg, iFrom);
      }else{
        fts5SegIterNext(p, pSeg);
      }
      fts5MultiIterAdvanced(p, pIter, iFirst, 1);
      bUseFrom = 0;
    }while( pIter->bSkipEmpty 
         && fts5SegIterIsDelete(p, &pIter->aSeg[pIter->aFirst[1]])
    );
  }
}

/*
** Allocate a new Fts5MultiSegIter object.
**
** The new object will be used to iterate through data in structure pStruct.
** If iLevel is -ve, then all data in all segments is merged. Or, if iLevel
** is zero or greater, data from the first nSegment segments on level iLevel
** is merged.
**
** The iterator initially points to the first term/rowid entry in the 
** iterated data.
*/
static void fts5MultiIterNew(
  Fts5Index *p,                   /* FTS5 backend to iterate within */
  Fts5Structure *pStruct,         /* Structure of specific index */
  int iIdx,                       /* Config.aHash[] index of FTS index */
  int bSkipEmpty,
  int flags,                      /* True for >= */
  const u8 *pTerm, int nTerm,     /* Term to seek to (or NULL/0) */
  int iLevel,                     /* Level to iterate (-1 for all) */
  int nSegment,                   /* Number of segments to merge (iLevel>=0) */
  Fts5MultiSegIter **ppOut        /* New object */
){
  int nSeg;                       /* Number of segments merged */

      sizeof(u16) * nSlot                 /* pNew->aFirst[] */
  );
  if( pNew==0 ) return;
  pNew->nSeg = nSlot;
  pNew->aSeg = (Fts5SegIter*)&pNew[1];
  pNew->aFirst = (u16*)&pNew->aSeg[nSlot];
  pNew->bRev = (0!=(flags & FTS5INDEX_QUERY_ASC));
  pNew->bSkipEmpty = bSkipEmpty;

  /* Initialize each of the component segment iterators. */
  if( iLevel<0 ){
    Fts5StructureLevel *pEnd = &pStruct->aLevel[pStruct->nLevel];
    for(pLvl=&pStruct->aLevel[0]; pLvl<pEnd; pLvl++){
      for(iSeg=pLvl->nSeg-1; iSeg>=0; iSeg--){
        Fts5StructureSegment *pSeg = &pLvl->aSeg[iSeg];

    for(iIter=nSlot-1; iIter>0; iIter--){
      int iEq;
      if( (iEq = fts5MultiIterDoCompare(pNew, iIter)) ){
        fts5SegIterNext(p, &pNew->aSeg[iEq]);
        fts5MultiIterAdvanced(p, pNew, iEq, iIter);
      }
    }

    if( pNew->bSkipEmpty 
     && fts5SegIterIsDelete(p, &pNew->aSeg[pNew->aFirst[1]]) 
    ){
      fts5MultiIterNext(p, pNew, 0, 0);
    }
  }else{
    fts5MultiIterFree(p, pNew);
    *ppOut = 0;
  }
}

/*

  bOldest = (pLvlOut->nSeg==1 && pStruct->nLevel==iLvl+2);

#if 0
fprintf(stdout, "merging %d segments from level %d!", nInput, iLvl);
fflush(stdout);
#endif

  for(fts5MultiIterNew(p, pStruct, iIdx, 0, 0, 0, 0, iLvl, nInput, &pIter);
      fts5MultiIterEof(p, pIter)==0;
      fts5MultiIterNext(p, pIter, 0, 0)
  ){
    Fts5SegIter *pSeg = &pIter->aSeg[ pIter->aFirst[1] ];
    Fts5ChunkIter sPos;           /* Used to iterate through position list */

    /* If the segment being written is the oldest in the entire index and

    Fts5DoclistIter *pDoclist;
    int i;
    i64 iLastRowid = 0;
    Fts5MultiSegIter *p1 = 0;     /* Iterator used to gather data from index */
    Fts5Buffer doclist;

    memset(&doclist, 0, sizeof(doclist));
    for(fts5MultiIterNew(p, pStruct, 0, 1, 1, pToken, nToken, -1, 0, &p1);
        fts5MultiIterEof(p, p1)==0;
        fts5MultiIterNext(p, p1, 0, 0)
    ){
      i64 iRowid = fts5MultiIterRowid(p1);
      int nTerm;
      const u8 *pTerm = fts5MultiIterTerm(p1, &nTerm);
      assert( memcmp(pToken, pTerm, MIN(nToken, nTerm))<=0 );

  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, 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);

    memset(pRet, 0, sizeof(Fts5IndexIter));

    pRet->pIndex = p;
    if( iIdx>=0 ){
      pRet->pStruct = fts5StructureRead(p, iIdx);
      if( pRet->pStruct ){
        fts5MultiIterNew(p, pRet->pStruct, 
            iIdx, 1, flags, (const u8*)pToken, nToken, -1, 0, &pRet->pMulti
        );
      }
    }else{
      int bAsc = (flags & FTS5INDEX_QUERY_ASC)!=0;
      fts5SetupPrefixIter(p, bAsc, (const u8*)pToken, nToken, pRet);
    }
  }

  char **pzErrMsg                 /* OUT: Error message (if any) */
){
  int rc = SQLITE_OK;

  assert( eStmt>=0 && eStmt<ArraySize(p->aStmt) );
  if( p->aStmt[eStmt]==0 ){
    const char *azStmt[] = {
      "SELECT * FROM %s ORDER BY %s ASC",               /* SCAN_ASC */
      "SELECT * FROM %s ORDER BY %s DESC",              /* SCAN_DESC */
      "SELECT * FROM %s WHERE %s=?",                    /* LOOKUP  */

      "INSERT INTO %Q.'%q_content' VALUES(%s)",         /* INSERT_CONTENT  */
      "REPLACE INTO %Q.'%q_content' VALUES(%s)",        /* REPLACE_CONTENT */
      "DELETE FROM %Q.'%q_content' WHERE id=?",         /* DELETE_CONTENT  */
      "REPLACE INTO %Q.'%q_docsize' VALUES(?,?)",       /* REPLACE_DOCSIZE  */
      "DELETE FROM %Q.'%q_docsize' WHERE id=?",         /* DELETE_DOCSIZE  */

      "SELECT sz FROM %Q.'%q_docsize' WHERE id=?",      /* LOOKUP_DOCSIZE  */

      "REPLACE INTO %Q.'%q_config' VALUES(?,?)",        /* REPLACE_CONFIG */
    };
    Fts5Config *pC = p->pConfig;
    char *zSql = 0;

    switch( eStmt ){
      case FTS5_STMT_SCAN_ASC:
      case FTS5_STMT_SCAN_DESC:



      case FTS5_STMT_LOOKUP:
        zSql = sqlite3_mprintf(azStmt[eStmt], pC->zContent, pC->zContentRowid);
        break;

      case FTS5_STMT_INSERT_CONTENT: 
      case FTS5_STMT_REPLACE_CONTENT: {
        int nCol = pC->nCol + 1;

    for(i=0; rc==SQLITE_OK && i<pConfig->nCol; i++){
      if( p->aTotalSize[i]!=aTotalSize[i] ) rc = SQLITE_CORRUPT_VTAB;
    }
  }

  /* Check that the %_docsize and %_content tables contain the expected
  ** number of rows.  */
  if( rc==SQLITE_OK && pConfig->eContent==FTS5_CONTENT_NORMAL ){
    i64 nRow;
    rc = fts5StorageCount(p, "content", &nRow);
    if( rc==SQLITE_OK && nRow!=p->nTotalRow ) rc = SQLITE_CORRUPT_VTAB;
  }
  if( rc==SQLITE_OK ){
    i64 nRow;
    rc = fts5StorageCount(p, "docsize", &nRow);

  SELECT t2 FROM t2 WHERE t2 MATCH '*stuff'
} {1 {unknown special query: stuff}}

do_test 12.3 {
  set res [db one { SELECT t2 FROM t2 WHERE t2 MATCH '* reads ' }]
  string is integer $res
} {1}

#-------------------------------------------------------------------------
#
reset_db
do_execsql_test 13.1 {
  CREATE VIRTUAL TABLE t1 USING fts5(x);
  INSERT INTO t1(rowid, x) VALUES(1, 'o n e'), (2, 't w o');
} {}

do_execsql_test 13.2 {
  SELECT rowid FROM t1 WHERE t1 MATCH 'o';
} {2 1}

do_execsql_test 13.4 {
  DELETE FROM t1 WHERE rowid=2;
} {}

do_execsql_test 13.5 {
  SELECT rowid FROM t1 WHERE t1 MATCH 'o';
} {1}

finish_test

if {![info exists testdir]} {
  set testdir [file join [file dirname [info script]] .. .. .. test]
}
source $testdir/tester.tcl
set testprefix fts5content

#-------------------------------------------------------------------------
# Contentless tables
#
do_execsql_test 1.1 {
  CREATE VIRTUAL TABLE f1 USING fts5(a, b, content='');
  INSERT INTO f1(rowid, a, b) VALUES(1, 'one',   'o n e');
  INSERT INTO f1(rowid, a, b) VALUES(2, 'two',   't w o');
  INSERT INTO f1(rowid, a, b) VALUES(3, 'three', 't h r e e');
}

  UPDATE f1 SET a = 'a b c' WHERE rowid = 2;
} {1 {cannot UPDATE contentless fts5 table: f1}}

do_execsql_test 1.15 {
  INSERT INTO f1(f1, rowid, a, b) VALUES('delete', 2, 'two', 't w o');
} {}




do_execsql_test 1.16 {
  SELECT rowid FROM f1 WHERE f1 MATCH 'o';
} {4 1}

do_execsql_test 1.17 {
  SELECT rowid FROM f1;
} {4 3 1}

#-------------------------------------------------------------------------
# External content tables
#
reset_db
do_execsql_test 2.1 {
  -- Create a table. And an external content fts5 table to index it.
  CREATE TABLE tbl(a INTEGER PRIMARY KEY, b, c);
  CREATE VIRTUAL TABLE fts_idx USING fts5(b, c, content='tbl', content_rowid='a');

  -- Triggers to keep the FTS index up to date.
  CREATE TRIGGER tbl_ai AFTER INSERT ON tbl BEGIN
    INSERT INTO fts_idx(rowid, b, c) VALUES (new.a, new.b, new.c);
  END;
  CREATE TRIGGER tbl_ad AFTER DELETE ON tbl BEGIN
    INSERT INTO fts_idx(fts_idx, rowid, b, c) 
        VALUES('delete', old.a, old.b, old.c);
  END;
  CREATE TRIGGER tbl_au AFTER UPDATE ON tbl BEGIN
    INSERT INTO fts_idx(fts_idx, rowid, b, c) 
        VALUES('delete', old.a, old.b, old.c);
    INSERT INTO fts_idx(rowid, b, c) VALUES (new.a, new.b, new.c);
  END;
}

do_execsql_test 2.2 {
  INSERT INTO tbl VALUES(1, 'one', 'o n e');
  INSERT INTO tbl VALUES(NULL, 'two', 't w o');
  INSERT INTO tbl VALUES(3, 'three', 't h r e e');
}

do_execsql_test 2.3 {
  INSERT INTO fts_idx(fts_idx) VALUES('integrity-check');
}

do_execsql_test 2.4 {
  DELETE FROM tbl WHERE rowid=2;
  INSERT INTO fts_idx(fts_idx) VALUES('integrity-check');
}

do_execsql_test 2.5 {
  UPDATE tbl SET c = c || ' x y z';
  INSERT INTO fts_idx(fts_idx) VALUES('integrity-check');
}

do_execsql_test 2.6 {
  SELECT * FROM fts_idx WHERE fts_idx MATCH 't AND x';
} {three {t h r e e x y z}}

do_execsql_test 2.7 {
  SELECT highlight(fts_idx, 1, '[', ']') FROM fts_idx 
  WHERE fts_idx MATCH 't AND x';
} {{[t] h r e e [x] y z}}


finish_test