SQLite

*/
static void fts3GetDeltaPosition(char **pp, int *piPos){
  int iVal;
  *pp += fts3GetVarint32(*pp, &iVal);
  *piPos += (iVal-2);
}

static int fts3ExprLHitsCb(Fts3Expr*, int, void*);

/*
** Helper function for fts3ExprIterate() (see below).
*/
static int fts3ExprIterate2(
  Fts3Expr *pExpr,                /* Expression to iterate phrases of */
  int *piPhrase,                  /* Pointer to phrase counter */
  int (*x)(Fts3Expr*,int,void*),  /* Callback function to invoke for phrases */
  void *pCtx                      /* Second argument to pass to callback */
){
  int rc;                         /* Return code */

  if( x==fts3ExprLHitsCb && pExpr->bEof ){
    rc = SQLITE_OK;
  }else{
    int eType = pExpr->eType;     /* Type of expression node pExpr */

    if( eType!=FTSQUERY_PHRASE ){
      assert( pExpr->pLeft && pExpr->pRight );
      rc = fts3ExprIterate2(pExpr->pLeft, piPhrase, x, pCtx);
      if( rc==SQLITE_OK && eType!=FTSQUERY_NOT ){
        rc = fts3ExprIterate2(pExpr->pRight, piPhrase, x, pCtx);
      }
    }else{
      rc = x(pExpr, *piPhrase, pCtx);
      (*piPhrase)++;
    }
  }
  return rc;
}

/*
** Iterate through all phrase nodes in an FTS3 query, except those that
** are part of a sub-tree that is the right-hand-side of a NOT operator.
** For each phrase node found, the supplied callback function is invoked.

    if( pCsr ){
      p->aMatchinfo[iStart+i*3] = fts3ColumnlistCount(&pCsr);
    }else{
      p->aMatchinfo[iStart+i*3] = 0;
    }
  }

  return rc;
}

/*
** fts3ExprIterate() callback used to gather information for the matchinfo
** directives 'y' and 'b'.
*/
static int fts3ExprLHitsCb(
  Fts3Expr *pExpr,                /* Phrase expression node */
  int iPhrase,                    /* Phrase number */
  void *pCtx                      /* Pointer to MatchInfo structure */
){
  int rc = SQLITE_OK;
  MatchInfo *p = (MatchInfo *)pCtx;
  
  /* This must be a phrase */
  assert( pExpr->pPhrase );

  if( pExpr->iDocid==p->pCursor->iPrevId ){
    Fts3Table *pTab = (Fts3Table *)p->pCursor->base.pVtab;
    int iStart;
    Fts3Phrase *pPhrase = pExpr->pPhrase;
    char *pIter = pPhrase->doclist.pList;
    int iCol = 0;

    assert( p->flag==FTS3_MATCHINFO_LHITS_BM || p->flag==FTS3_MATCHINFO_LHITS );
    if( p->flag==FTS3_MATCHINFO_LHITS ){
      iStart = iPhrase * p->nCol;
    }else{
      iStart = iPhrase * ((p->nCol + 31) / 32);
    }

    while( 1 ){
      int nHit = fts3ColumnlistCount(&pIter);
      if( (pPhrase->iColumn>=pTab->nColumn || pPhrase->iColumn==iCol) ){
        if( p->flag==FTS3_MATCHINFO_LHITS ){
          p->aMatchinfo[iStart + iCol] = (u32)nHit;
        }else if( nHit ){
          p->aMatchinfo[iStart + (iCol+1)/32] |= (1 << (iCol&0x1F));
        }
      }
      assert( *pIter==0x00 || *pIter==0x01 );
      if( *pIter!=0x01 ) break;
      pIter++;
      pIter += fts3GetVarint32(pIter, &iCol);
    }
  }

  return rc;
}

static int fts3MatchinfoCheck(
  Fts3Table *pTab, 
  char cArg,
  char **pzErr