SQLite

      ** edited in place by fts3EvalNearTrim2(), then pIter may not actually
      ** point to the start of the next docid value. The following line deals
      ** with this case by advancing pIter past the zero-padding added by
      ** fts3EvalNearTrim2().  */
      while( pIter<pEnd && *pIter==0 ) pIter++;

      pDL->pNextDocid = pIter;
      assert( *pIter || pIter>=&pDL->aAll[pDL->nAll] );
      assert( pIter>=&pDL->aAll[pDL->nAll] || *pIter );
      *pbEof = 0;
    }
  }

  return rc;
}

){
  if( pExpr && *pRc==SQLITE_OK ){
    Fts3Phrase *pPhrase = pExpr->pPhrase;

    if( pPhrase ){
      fts3EvalZeroPoslist(pPhrase);
      if( pPhrase->bIncr ){
        sqlite3Fts3EvalPhraseCleanup(pPhrase);
        memset(&pPhrase->doclist, 0, sizeof(Fts3Doclist));
        *pRc = sqlite3Fts3EvalStart(pCsr, pExpr, 0);
      }else{
        assert( pPhrase->nToken==1 );
        assert( pPhrase->aToken[0].pSegcsr );
        sqlite3Fts3MsrIncrRestart(pPhrase->aToken[0].pSegcsr);
        *pRc = fts3EvalPhraseStart(pCsr, 0, pPhrase);
      }

        pPhrase->doclist.pNextDocid = 0;
        pPhrase->doclist.iDocid = 0;
      }
    }

    pExpr->iDocid = 0;
    pExpr->bEof = 0;
    pExpr->bStart = 0;

    fts3EvalRestart(pCsr, pExpr->pLeft, pRc);
    fts3EvalRestart(pCsr, pExpr->pRight, pRc);

  int nSegment;                   /* Size of apSegment array */
  int nAdvance;                   /* How many seg-readers to advance */
  Fts3SegFilter *pFilter;         /* Pointer to filter object */
  char *aBuffer;                  /* Buffer to merge doclists in */
  int nBuffer;                    /* Allocated size of aBuffer[] in bytes */

  int iColFilter;                 /* If >=0, filter for this column */
  int bRestart;

  /* Used by fts3.c only. */
  int nCost;                      /* Cost of running iterator */
  int bLookup;                    /* True if a lookup of a single entry. */

  /* Output values. Valid only after Fts3SegReaderStep() returns SQLITE_ROW. */
  char *zTerm;                    /* Pointer to term buffer */

    );
    if( bEof ){
      pReader->pOffsetList = 0;
    }else{
      pReader->pOffsetList = p;
    }
  }else{
    char *pEnd = &pReader->aDoclist[pReader->nDoclist];

    /* Pointer p currently points at the first byte of an offset list. The
    ** following block advances it to point one byte past the end of
    ** the same offset list. */
    while( 1 ){
  
      /* The following line of code (and the "p++" below the while() loop) is

    /* If required, populate the output variables with a pointer to and the
    ** size of the previous offset-list.
    */
    if( ppOffsetList ){
      *ppOffsetList = pReader->pOffsetList;
      *pnOffsetList = (int)(p - pReader->pOffsetList - 1);
    }

    while( p<pEnd && *p==0 ) p++;
  
    /* If there are no more entries in the doclist, set pOffsetList to
    ** NULL. Otherwise, set Fts3SegReader.iDocid to the next docid and
    ** Fts3SegReader.pOffsetList to point to the next offset list before
    ** returning.
    */
    if( p>=&pReader->aDoclist[pReader->nDoclist] ){
    if( p>=pEnd ){
      pReader->pOffsetList = 0;
    }else{
      rc = fts3SegReaderRequire(pReader, p, FTS3_VARINT_MAX);
      if( rc==SQLITE_OK ){
        sqlite3_int64 iDelta;
        pReader->pOffsetList = p + sqlite3Fts3GetVarint(p, &iDelta);
        if( pTab->bDescIdx ){

    p += sqlite3Fts3GetVarint32(p, &iCurrent);
  }

  *ppList = pList;
  *pnList = nList;
}

/*
** Cache data in the Fts3MultiSegReader.aBuffer[] buffer (overwriting any
** existing data). Grow the buffer if required.
**
** If successful, return SQLITE_OK. Otherwise, if an OOM error is encountered
** trying to resize the buffer, return SQLITE_NOMEM.
*/
int sqlite3Fts3MsrIncrStart(
static int fts3MsrBufferData(
  Fts3Table *p,                   /* Virtual table handle */
  Fts3MultiSegReader *pCsr,       /* Cursor object */
  Fts3MultiSegReader *pMsr,       /* Multi-segment-reader handle */
  int iCol,                       /* Column to match on. */
  const char *zTerm,              /* Term to iterate through a doclist for */
  int nTerm                       /* Number of bytes in zTerm */
  char *pList,
  int nList
){
  int i;
  int nSegment = pCsr->nSegment;
  if( nList>pMsr->nBuffer ){
  int (*xCmp)(Fts3SegReader *, Fts3SegReader *) = (
    p->bDescIdx ? fts3SegReaderDoclistCmpRev : fts3SegReaderDoclistCmp
  );

  assert( pCsr->pFilter==0 );
    char *pNew;
    pMsr->nBuffer = nList*2;
  assert( zTerm && nTerm>0 );

    pNew = (char *)sqlite3_realloc(pMsr->aBuffer, pMsr->nBuffer);
  /* Advance each segment iterator until it points to the term zTerm/nTerm. */
  for(i=0; i<nSegment; i++){
    Fts3SegReader *pSeg = pCsr->apSegment[i];
    do {
      int rc = fts3SegReaderNext(p, pSeg, 1);
      if( rc!=SQLITE_OK ) return rc;
    }while( fts3SegReaderTermCmp(pSeg, zTerm, nTerm)<0 );
  }
  fts3SegReaderSort(pCsr->apSegment, nSegment, nSegment, fts3SegReaderCmp);

    if( !pNew ) return SQLITE_NOMEM;
  /* Determine how many of the segments actually point to zTerm/nTerm. */
  for(i=0; i<nSegment; i++){
    Fts3SegReader *pSeg = pCsr->apSegment[i];
    if( !pSeg->aNode || fts3SegReaderTermCmp(pSeg, zTerm, nTerm) ){
      break;
    }
  }
  pCsr->nAdvance = i;

    pMsr->aBuffer = pNew;
  /* Advance each of the segments to point to the first docid. */
  for(i=0; i<pCsr->nAdvance; i++){
    int rc = fts3SegReaderFirstDocid(p, pCsr->apSegment[i]);
    if( rc!=SQLITE_OK ) return rc;
  }
  fts3SegReaderSort(pCsr->apSegment, i, i, xCmp);

  assert( iCol<0 || iCol<p->nColumn );
  pCsr->iColFilter = iCol;

  memcpy(pMsr->aBuffer, pList, nList);
  return SQLITE_OK;
}

int sqlite3Fts3MsrIncrNext(
  Fts3Table *p,                   /* Virtual table handle */
  Fts3MultiSegReader *pMsr,       /* Multi-segment-reader handle */
  sqlite3_int64 *piDocid,         /* OUT: Docid value */

      fts3SegReaderSort(pMsr->apSegment, nMerge, j, xCmp);

      if( pMsr->iColFilter>=0 ){
        fts3ColumnFilter(pMsr->iColFilter, &pList, &nList);
      }

      if( nList>0 ){
        if( fts3SegReaderIsPending(apSegment[0]) ){
          rc = fts3MsrBufferData(pMsr, pList, nList+1);
          if( rc!=SQLITE_OK ) return rc;
        *piDocid = iDocid;
          *paPoslist = pMsr->aBuffer;
          assert( (pMsr->aBuffer[nList] & 0xFE)==0x00 );
        }else{
        *paPoslist = pList;
        }
        *piDocid = iDocid;
        *pnPoslist = nList;
        break;
      }
    }
    
  }

  }

  return SQLITE_OK;
}

static int fts3SegReaderStart(
  Fts3Table *p,                   /* Virtual table handle */
  Fts3MultiSegReader *pCsr,       /* Cursor object */
  const char *zTerm,              /* Term searched for (or NULL) */
  int nTerm                       /* Length of zTerm in bytes */
){
  int i;
  int nSeg = pCsr->nSegment;

  /* If the Fts3SegFilter defines a specific term (or term prefix) to search 
  ** for, then advance each segment iterator until it points to a term of
  ** equal or greater value than the specified term. This prevents many
  ** unnecessary merge/sort operations for the case where single segment
  ** b-tree leaf nodes contain more than one term.
  */
  for(i=0; pCsr->bRestart==0 && i<pCsr->nSegment; i++){
    Fts3SegReader *pSeg = pCsr->apSegment[i];
    do {
      int rc = fts3SegReaderNext(p, pSeg, 0);
      if( rc!=SQLITE_OK ) return rc;
    }while( zTerm && fts3SegReaderTermCmp(pSeg, zTerm, nTerm)<0 );
  }
  fts3SegReaderSort(pCsr->apSegment, nSeg, nSeg, fts3SegReaderCmp);

  return SQLITE_OK;
}

int sqlite3Fts3SegReaderStart(
  Fts3Table *p,                   /* Virtual table handle */
  Fts3MultiSegReader *pCsr,       /* Cursor object */
  Fts3SegFilter *pFilter          /* Restrictions on range of iteration */
){
  pCsr->pFilter = pFilter;
  return fts3SegReaderStart(p, pCsr, pFilter->zTerm, pFilter->nTerm);
}

int sqlite3Fts3MsrIncrStart(
  Fts3Table *p,                   /* Virtual table handle */
  Fts3MultiSegReader *pCsr,       /* Cursor object */
  int iCol,                       /* Column to match on. */
  const char *zTerm,              /* Term to iterate through a doclist for */
  int nTerm                       /* Number of bytes in zTerm */
){
  int i;
  int rc;
  int nSegment = pCsr->nSegment;
  int (*xCmp)(Fts3SegReader *, Fts3SegReader *) = (
    p->bDescIdx ? fts3SegReaderDoclistCmpRev : fts3SegReaderDoclistCmp
  );

  /* Initialize the cursor object */
  pCsr->pFilter = pFilter;
  assert( pCsr->pFilter==0 );
  assert( zTerm && nTerm>0 );

  /* If the Fts3SegFilter defines a specific term (or term prefix) to search 
  ** for, then advance each segment iterator until it points to a term of
  ** equal or greater value than the specified term. This prevents many
  ** unnecessary merge/sort operations for the case where single segment
  /* Advance each segment iterator until it points to the term zTerm/nTerm. */
  rc = fts3SegReaderStart(p, pCsr, zTerm, nTerm);
  if( rc!=SQLITE_OK ) return rc;

  /* Determine how many of the segments actually point to zTerm/nTerm. */
  ** b-tree leaf nodes contain more than one term.
  */
  for(i=0; i<pCsr->nSegment; i++){
  for(i=0; i<nSegment; i++){
    int nTerm = pFilter->nTerm;
    const char *zTerm = pFilter->zTerm;
    Fts3SegReader *pSeg = pCsr->apSegment[i];
    if( !pSeg->aNode || fts3SegReaderTermCmp(pSeg, zTerm, nTerm) ){
      break;
    }
  }
  pCsr->nAdvance = i;
    do {
      int rc = fts3SegReaderNext(p, pSeg, 0);

  /* Advance each of the segments to point to the first docid. */
  for(i=0; i<pCsr->nAdvance; i++){
    rc = fts3SegReaderFirstDocid(p, pCsr->apSegment[i]);
      if( rc!=SQLITE_OK ) return rc;
    }while( zTerm && fts3SegReaderTermCmp(pSeg, zTerm, nTerm)<0 );
  }
  fts3SegReaderSort(
      pCsr->apSegment, pCsr->nSegment, pCsr->nSegment, fts3SegReaderCmp);
  fts3SegReaderSort(pCsr->apSegment, i, i, xCmp);

  assert( iCol<0 || iCol<p->nColumn );
  pCsr->iColFilter = iCol;

  return SQLITE_OK;
}

/*
** This function is called on a MultiSegReader that has been started using
** sqlite3Fts3MsrIncrStart(). One or more calls to MsrIncrNext() may also
** have been made. Calling this function puts the MultiSegReader in such
** a state that if the next two calls are:
**
**   sqlite3Fts3SegReaderStart()
**   sqlite3Fts3SegReaderStep()
**
** then the entire doclist for the term is available in 
** MultiSegReader.aDoclist/nDoclist.
*/
int sqlite3Fts3MsrIncrRestart(Fts3MultiSegReader *pCsr){
  int i;                          /* Used to iterate through segment-readers */

  assert( pCsr->zTerm==0 );
  assert( pCsr->nTerm==0 );
  assert( pCsr->aDoclist==0 );
  assert( pCsr->nDoclist==0 );

  pCsr->nAdvance = 0;
  pCsr->bRestart = 1;
  for(i=0; i<pCsr->nSegment; i++){
    pCsr->apSegment[i]->pOffsetList = 0;
    pCsr->apSegment[i]->nOffsetList = 0;
    pCsr->apSegment[i]->iDocid = 0;
  }

  return SQLITE_OK;
}


int sqlite3Fts3SegReaderStep(
  Fts3Table *p,                   /* Virtual table handle */
  Fts3MultiSegReader *pCsr        /* Cursor object */
){
  int rc = SQLITE_OK;

    }

    assert( isIgnoreEmpty || (isRequirePos && !isColFilter) );
    if( nMerge==1 
     && !isIgnoreEmpty 
     && (p->bDescIdx==0 || fts3SegReaderIsPending(apSegment[0])==0)
    ){
      pCsr->nDoclist = apSegment[0]->nDoclist;
      if( fts3SegReaderIsPending(apSegment[0]) ){
        rc = fts3MsrBufferData(pCsr, apSegment[0]->aDoclist, pCsr->nDoclist);
      pCsr->aDoclist = apSegment[0]->aDoclist;
      pCsr->nDoclist = apSegment[0]->nDoclist;
      rc = SQLITE_ROW;
        pCsr->aDoclist = pCsr->aBuffer;
      }else{
        pCsr->aDoclist = apSegment[0]->aDoclist;
      }
      if( rc==SQLITE_OK ) rc = SQLITE_ROW;
    }else{
      int nDoclist = 0;           /* Size of doclist */
      sqlite3_int64 iPrev = 0;    /* Previous docid stored in doclist */

      /* The current term of the first nMerge entries in the array
      ** of Fts3SegReader objects is the same. The doclists must be merged
      ** and a single term returned with the merged doclist.

    expr {[fts3_zero_long_segments t1 $limit]>0}
  } {1}

  do_fts3query_test 4.$tn.3.1 -deferred five t1 {one AND five}
  do_fts3query_test 4.$tn.3.2 -deferred five t1 {one NEAR five}
  do_fts3query_test 4.$tn.3.3 -deferred five t1 {one NEAR/1 five}
  do_fts3query_test 4.$tn.3.4 -deferred five t1 {one NEAR/2 five}

  do_fts3query_test 4.$tn.3.5 -deferred five t1 {one NEAR/3 five}

  do_fts3query_test 4.$tn.4.1 -deferred fi* t1 {on* AND fi*}
  do_fts3query_test 4.$tn.4.2 -deferred fi* t1 {on* NEAR fi*}
  do_fts3query_test 4.$tn.4.3 -deferred fi* t1 {on* NEAR/1 fi*}
  do_fts3query_test 4.$tn.4.4 -deferred fi* t1 {on* NEAR/2 fi*}
  do_fts3query_test 4.$tn.4.5 -deferred fi* t1 {on* NEAR/3 fi*}
}

#--------------------------------------------------------------------------
# The following test cases - fts3auto-5.* - focus on using prefix indexes.
#
set chunkconfig [fts3_configure_incr_load 1 1]
foreach {tn create} {
foreach {tn create pending} {
  1    "fts4(a, b)"
  2    "fts4(a, b, order=DESC, prefix=1)"
  3    "fts4(a, b, order=ASC,  prefix=1,3)"
  4    "fts4(a, b, order=DESC, prefix=2,4)"
  2    "fts4(a, b, order=ASC, prefix=1)"             1

  1    "fts4(a, b)"                                  1
  3    "fts4(a, b, order=ASC,  prefix=1,3)"          0
  4    "fts4(a, b, order=DESC, prefix=2,4)"          0
  5    "fts4(a, b, order=DESC, prefix=1)"            0
  6    "fts4(a, b, order=ASC,  prefix=1,3)"          0
} {

  execsql [subst {
    DROP TABLE t1;
    DROP TABLE IF EXISTS t1;
    CREATE VIRTUAL TABLE t1 USING $create;
  }]

  if {$pending} {execsql BEGIN}

  foreach {a b} {
    "the song of songs which is solomons"
    "let him kiss me with the kisses of his mouth for thy love is better than wine"
    "because of the savour of thy good ointments thy name is as ointment poured forth therefore do the virgins love thee"
    "draw me we will run after thee the king hath brought me into his chambers we will be glad and rejoice in thee we will remember thy love more than wine the upright love thee"
    "i am black but comely o ye daughters of jerusalem as the tents of kedar as the curtains of solomon"

    "my beloved is unto me as a cluster of camphire in the vineyards of en gedi"
    "behold thou art fair my love behold thou art fair thou hast doves eyes"
    "behold thou art fair my beloved yea pleasant also our bed is green"
    "the beams of our house are cedar and our rafters of fir"
  } {
    execsql {INSERT INTO t1(a, b) VALUES($a, $b)}
  }


  do_fts3query_test 5.$tn.1.1 t1 {s*}
  do_fts3query_test 5.$tn.1.2 t1 {so*}
  do_fts3query_test 5.$tn.1.3 t1 {"s* o*"}
  do_fts3query_test 5.$tn.1.4 t1 {b* NEAR/3 a*}
  do_fts3query_test 5.$tn.1.5 t1 {th* NEAR/5 a* NEAR/5 w*}
  do_fts3query_test 5.$tn.1.6 t1 {"b* th* art* fair*"}
  do_fts3query_test 5.$tn.1.5 t1 {a*}
  do_fts3query_test 5.$tn.1.6 t1 {th* NEAR/5 a* NEAR/5 w*}
  do_fts3query_test 5.$tn.1.7 t1 {"b* th* art* fair*"}

  if {$pending} {execsql COMMIT}
}
eval fts3_configure_incr_load $chunkconfig

set sqlite_fts3_enable_parentheses $sfep
finish_test