SQLite

    return SQLITE_OK;
  }

  iDocid = pExpr->iDocid;
  pIter = pPhrase->doclist.pList;
  if( iDocid!=pCsr->iPrevId || pExpr->bEof ){
    int bDescDoclist = pTab->bDescIdx;      /* For DOCID_CMP macro */
    int iMul;                     /* +1 if csr dir matches index dir, else -1 */
    int bOr = 0;
    u8 bEof = 0;
    u8 bTreeEof = 0;
    Fts3Expr *p;                  /* Used to iterate from pExpr to root */
    Fts3Expr *pNear;              /* Most senior NEAR ancestor (or pExpr) */

    /* Check if this phrase descends from an OR expression node. If not, 
    ** return NULL. Otherwise, the entry that corresponds to docid 
    ** pCsr->iPrevId may lie earlier in the doclist buffer. Or, if the
    ** tree that the node is part of has been marked as EOF, but the node
    ** itself is not EOF, then it may point to an earlier entry. */
    pNear = pExpr;
    for(p=pExpr->pParent; p; p=p->pParent){
      if( p->eType==FTSQUERY_OR ) bOr = 1;
      if( p->eType==FTSQUERY_NEAR ) pNear = p;
      if( p->bEof ) bTreeEof = 1;
    }
    if( bOr==0 ) return SQLITE_OK;

    /* This is the descendent of an OR node. In this case we cannot use
    ** an incremental phrase. Load the entire doclist for the phrase
    ** into memory in this case.  */
    if( pPhrase->bIncr ){
      int rc = SQLITE_OK;
      int bEofSave = pExpr->bEof;
      fts3EvalRestart(pCsr, pExpr, &rc);
      while( rc==SQLITE_OK && !pExpr->bEof ){
        fts3EvalNextRow(pCsr, pExpr, &rc);
        if( bEofSave==0 && pExpr->iDocid==iDocid ) break;
      }
      pIter = pPhrase->doclist.pList;
      assert( rc!=SQLITE_OK || pPhrase->bIncr==0 );
      if( rc!=SQLITE_OK ) return rc;
    }
    
    iMul = ((pCsr->bDesc==bDescDoclist) ? 1 : -1);
    while( bTreeEof==1 
        && pNear->bEof==0
        && (DOCID_CMP(pNear->iDocid, pCsr->iPrevId) * iMul)<0
    ){
      int rc = SQLITE_OK;
      fts3EvalNextRow(pCsr, pExpr, &rc);
      if( rc!=SQLITE_OK ) return rc;
      iDocid = pExpr->iDocid;
      pIter = pPhrase->doclist.pList;
    }

    bEof = (pPhrase->doclist.nAll==0);
    assert( bDescDoclist==0 || bDescDoclist==1 );
    assert( pCsr->bDesc==0 || pCsr->bDesc==1 );

    if( bEof==0 ){
      if( pCsr->bDesc==bDescDoclist ){
        int dummy;
        if( pNear->bEof ){
          /* This expression is already at EOF. So position it to point to the
          ** last entry in the doclist at pPhrase->doclist.aAll[]. Variable
          ** iDocid is already set for this entry, so all that is required is
          ** to set pIter to point to the first byte of the last position-list
          ** in the doclist. 
          **
          ** It would also be correct to set pIter and iDocid to zero. In
          ** this case, the first call to sqltie3Fts4DoclistPrev() below
          ** would also move the iterator to point to the last entry in the 
          ** doclist. However, this is expensive, as to do so it has to 
          ** iterate through the entire doclist from start to finish (since
          ** it does not know the docid for the last entry).  */
          pIter = &pPhrase->doclist.aAll[pPhrase->doclist.nAll-1];
          fts3ReversePoslist(pPhrase->doclist.aAll, &pIter);
        }
        while( (pIter==0 || DOCID_CMP(iDocid, pCsr->iPrevId)>0 ) && bEof==0 ){
          sqlite3Fts3DoclistPrev(
              bDescDoclist, pPhrase->doclist.aAll, pPhrase->doclist.nAll, 
              &pIter, &iDocid, &dummy, &bEof
          );
        }
      }else{
        if( pNear->bEof ){
          pIter = 0;
          iDocid = 0;
        }
        while( (pIter==0 || DOCID_CMP(iDocid, pCsr->iPrevId)<0 ) && bEof==0 ){
          sqlite3Fts3DoclistNext(
              bDescDoclist, pPhrase->doclist.aAll, pPhrase->doclist.nAll, 
              &pIter, &iDocid, &bEof
          );
        }
      }
    }

    if( bEof || iDocid!=pCsr->iPrevId ) pIter = 0;
  }
  if( pIter==0 ) return SQLITE_OK;

# The tests in this file test the FTS3 auxillary functions offsets(), 
# snippet() and matchinfo() work. At time of writing, running this file 
# provides full coverage of fts3_snippet.c.
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
set testprefix fts3snippet

# If SQLITE_ENABLE_FTS3 is not defined, omit this file.
ifcapable !fts3 { finish_test ; return }
source $testdir/fts3_common.tcl

set sqlite_fts3_enable_parentheses 1
set DO_MALLOC_TEST 0

  forcedelete test.db
  sqlite3 db test.db
  sqlite3_db_config_lookaside db 0 0 0
  db eval "PRAGMA encoding = \"$enc\""

  # Set variable $T to the test name prefix for this iteration of the loop.
  #
  set T "fts3snippet-1.$enc"

  ##########################################################################
  # Test the offset function.
  #
  do_test $T.1.1 {
    execsql {
      CREATE VIRTUAL TABLE ft USING fts3;

  do_select_test $T.10.5 {
    SELECT length(matchinfo(ft)), typeof(matchinfo(ft)) FROM ft;
  } {0 blob 0 blob 0 blob}
  do_select_test $T.10.6 {
    SELECT length(matchinfo(ft)), typeof(matchinfo(ft)) FROM ft WHERE rowid = $r
  } {0 blob}
}

#-------------------------------------------------------------------------
# Test an interaction between the snippet() function and OR clauses.
#
do_execsql_test 2.1 {
  CREATE VIRTUAL TABLE t2 USING fts4;
  INSERT INTO t2 VALUES('one two three four five');
  INSERT INTO t2 VALUES('two three four five one');
  INSERT INTO t2 VALUES('three four five one two');
  INSERT INTO t2 VALUES('four five one two three');
  INSERT INTO t2 VALUES('five one two three four');
}

do_execsql_test 2.2 {
  SELECT snippet(t2, '[', ']') FROM t2 WHERE t2 MATCH 'one OR (four AND six)'
} {
  {[one] two three [four] five}
  {two three [four] five [one]}
  {three [four] five [one] two}
  {[four] five [one] two three}
  {five [one] two three [four]}
}

do_execsql_test 2.3 {
  SELECT snippet(t2, '[', ']') FROM t2 
  WHERE t2 MATCH 'one OR (four AND six)' 
  ORDER BY docid DESC
} {
  {five [one] two three [four]}
  {[four] five [one] two three}
  {three [four] five [one] two}
  {two three [four] five [one]}
  {[one] two three [four] five}
}

do_execsql_test 2.4 {
  INSERT INTO t2 VALUES('six');
}

do_execsql_test 2.5 {
  SELECT snippet(t2, '[', ']') FROM t2 WHERE t2 MATCH 'one OR (four AND six)'
} {
  {[one] two three [four] five}
  {two three [four] five [one]}
  {three [four] five [one] two}
  {[four] five [one] two three}
  {five [one] two three [four]}
}

do_execsql_test 2.6 {
  SELECT snippet(t2, '[', ']') FROM t2 
  WHERE t2 MATCH 'one OR (four AND six)' 
  ORDER BY docid DESC
} {
  {five [one] two three [four]}
  {[four] five [one] two three}
  {three [four] five [one] two}
  {two three [four] five [one]}
  {[one] two three [four] five}
}

set sqlite_fts3_enable_parentheses 0
finish_test