Import SQLite 3.10.2.

third_party/sqlite/src/ext/fts3/fts3_snippet.c

 /*
 ** 2009 Oct 23
 **
 ** The author disclaims copyright to this source code.  In place of
 ** a legal notice, here is a blessing:
 **
 **    May you do good and not evil.
 **    May you find forgiveness for yourself and forgive others.
 **    May you share freely, never taking more than you give.
 **
 ******************************************************************************
 */
 
 #include "fts3Int.h"
 #if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
 
 #include <string.h>
 #include <assert.h>
 
 /*
 ** Characters that may appear in the second argument to matchinfo().
 */
 #define FTS3_MATCHINFO_NPHRASE   'p'        /* 1 value */
 #define FTS3_MATCHINFO_NCOL      'c'        /* 1 value */
 #define FTS3_MATCHINFO_NDOC      'n'        /* 1 value */
 #define FTS3_MATCHINFO_AVGLENGTH 'a'        /* nCol values */
 #define FTS3_MATCHINFO_LENGTH    'l'        /* nCol values */
 #define FTS3_MATCHINFO_LCS       's'        /* nCol values */
 #define FTS3_MATCHINFO_HITS      'x'        /* 3*nCol*nPhrase values */
+#define FTS3_MATCHINFO_LHITS     'y'        /* nCol*nPhrase values */
+#define FTS3_MATCHINFO_LHITS_BM  'b'        /* nCol*nPhrase values */
 
 /*
 ** The default value for the second argument to matchinfo(). 
 */
 #define FTS3_MATCHINFO_DEFAULT   "pcx"
 
 
 /*
 ** Used as an fts3ExprIterate() context when loading phrase doclists to
 ** Fts3Expr.aDoclist[]/nDoclist.
@@ skipping 41 matching lines @@
 /*
 ** This type is used as an fts3ExprIterate() context object while 
 ** accumulating the data returned by the matchinfo() function.
 */
 typedef struct MatchInfo MatchInfo;
 struct MatchInfo {
   Fts3Cursor *pCursor;            /* FTS3 Cursor */
   int nCol;                       /* Number of columns in table */
   int nPhrase;                    /* Number of matchable phrases in query */
   sqlite3_int64 nDoc;             /* Number of docs in database */
+  char flag;
   u32 *aMatchinfo;                /* Pre-allocated buffer */
 };
 
+/*
+** An instance of this structure is used to manage a pair of buffers, each
+** (nElem * sizeof(u32)) bytes in size. See the MatchinfoBuffer code below
+** for details.
+*/
+struct MatchinfoBuffer {
+  u8 aRef[3];
+  int nElem;
+  int bGlobal;                    /* Set if global data is loaded */
+  char *zMatchinfo;
+  u32 aMatchinfo[1];
+};
 
 
 /*
 ** The snippet() and offsets() functions both return text values. An instance
 ** of the following structure is used to accumulate those values while the
 ** functions are running. See fts3StringAppend() for details.
 */
 typedef struct StrBuffer StrBuffer;
 struct StrBuffer {
   char *z;                        /* Pointer to buffer containing string */
   int n;                          /* Length of z in bytes (excl. nul-term) */
   int nAlloc;                     /* Allocated size of buffer z in bytes */
 };
 
 
+/*************************************************************************
+** Start of MatchinfoBuffer code.
+*/
+
+/*
+** Allocate a two-slot MatchinfoBuffer object.
+*/
+static MatchinfoBuffer *fts3MIBufferNew(int nElem, const char *zMatchinfo){
+  MatchinfoBuffer *pRet;
+  int nByte = sizeof(u32) * (2*nElem + 1) + sizeof(MatchinfoBuffer);
+  int nStr = (int)strlen(zMatchinfo);
+
+  pRet = sqlite3_malloc(nByte + nStr+1);
+  if( pRet ){
+    memset(pRet, 0, nByte);
+    pRet->aMatchinfo[0] = (u8*)(&pRet->aMatchinfo[1]) - (u8*)pRet;
+    pRet->aMatchinfo[1+nElem] = pRet->aMatchinfo[0] + sizeof(u32)*(nElem+1);
+    pRet->nElem = nElem;
+    pRet->zMatchinfo = ((char*)pRet) + nByte;
+    memcpy(pRet->zMatchinfo, zMatchinfo, nStr+1);
+    pRet->aRef[0] = 1;
+  }
+
+  return pRet;
+}
+
+static void fts3MIBufferFree(void *p){
+  MatchinfoBuffer *pBuf = (MatchinfoBuffer*)((u8*)p - ((u32*)p)[-1]);
+
+  assert( (u32*)p==&pBuf->aMatchinfo[1] 
+       || (u32*)p==&pBuf->aMatchinfo[pBuf->nElem+2] 
+  );
+  if( (u32*)p==&pBuf->aMatchinfo[1] ){
+    pBuf->aRef[1] = 0;
+  }else{
+    pBuf->aRef[2] = 0;
+  }
+
+  if( pBuf->aRef[0]==0 && pBuf->aRef[1]==0 && pBuf->aRef[2]==0 ){
+    sqlite3_free(pBuf);
+  }
+}
+
+static void (*fts3MIBufferAlloc(MatchinfoBuffer *p, u32 **paOut))(void*){
+  void (*xRet)(void*) = 0;
+  u32 *aOut = 0;
+
+  if( p->aRef[1]==0 ){
+    p->aRef[1] = 1;
+    aOut = &p->aMatchinfo[1];
+    xRet = fts3MIBufferFree;
+  }
+  else if( p->aRef[2]==0 ){
+    p->aRef[2] = 1;
+    aOut = &p->aMatchinfo[p->nElem+2];
+    xRet = fts3MIBufferFree;
+  }else{
+    aOut = (u32*)sqlite3_malloc(p->nElem * sizeof(u32));
+    if( aOut ){
+      xRet = sqlite3_free;
+      if( p->bGlobal ) memcpy(aOut, &p->aMatchinfo[1], p->nElem*sizeof(u32));
+    }
+  }
+
+  *paOut = aOut;
+  return xRet;
+}
+
+static void fts3MIBufferSetGlobal(MatchinfoBuffer *p){
+  p->bGlobal = 1;
+  memcpy(&p->aMatchinfo[2+p->nElem], &p->aMatchinfo[1], p->nElem*sizeof(u32));
+}
+
+/*
+** Free a MatchinfoBuffer object allocated using fts3MIBufferNew()
+*/
+void sqlite3Fts3MIBufferFree(MatchinfoBuffer *p){
+  if( p ){
+    assert( p->aRef[0]==1 );
+    p->aRef[0] = 0;
+    if( p->aRef[0]==0 && p->aRef[1]==0 && p->aRef[2]==0 ){
+      sqlite3_free(p);
+    }
+  }
+}
+
+/* 
+** End of MatchinfoBuffer code.
+*************************************************************************/
+
+
 /*
 ** This function is used to help iterate through a position-list. A position
 ** list is a list of unique integers, sorted from smallest to largest. Each
 ** element of the list is represented by an FTS3 varint that takes the value
 ** of the difference between the current element and the previous one plus
 ** two. For example, to store the position-list:
 **
 **     4 9 113
 **
 ** the three varints:
@@ skipping 16 matching lines @@
 /*
 ** 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 */
-  int eType = pExpr->eType;       /* Type of expression node pExpr */
+  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)++;
@@ skipping 13 matching lines @@
 */
 static int fts3ExprIterate(
   Fts3Expr *pExpr,                /* Expression to iterate phrases of */
   int (*x)(Fts3Expr*,int,void*),  /* Callback function to invoke for phrases */
   void *pCtx                      /* Second argument to pass to callback */
 ){
   int iPhrase = 0;                /* Variable used as the phrase counter */
   return fts3ExprIterate2(pExpr, &iPhrase, x, pCtx);
 }
 
+
 /*
 ** This is an fts3ExprIterate() callback used while loading the doclists
 ** for each phrase into Fts3Expr.aDoclist[]/nDoclist. See also
 ** fts3ExprLoadDoclists().
 */
 static int fts3ExprLoadDoclistsCb(Fts3Expr *pExpr, int iPhrase, void *ctx){
   int rc = SQLITE_OK;
   Fts3Phrase *pPhrase = pExpr->pPhrase;
   LoadDoclistCtx *p = (LoadDoclistCtx *)ctx;
 
@@ skipping 24 matching lines @@
   LoadDoclistCtx sCtx = {0,0,0};  /* Context for fts3ExprIterate() */
   sCtx.pCsr = pCsr;
   rc = fts3ExprIterate(pCsr->pExpr, fts3ExprLoadDoclistsCb, (void *)&sCtx);
   if( pnPhrase ) *pnPhrase = sCtx.nPhrase;
   if( pnToken ) *pnToken = sCtx.nToken;
   return rc;
 }
 
 static int fts3ExprPhraseCountCb(Fts3Expr *pExpr, int iPhrase, void *ctx){
   (*(int *)ctx)++;
-  UNUSED_PARAMETER(pExpr);
-  UNUSED_PARAMETER(iPhrase);
+  pExpr->iPhrase = iPhrase;
   return SQLITE_OK;
 }
 static int fts3ExprPhraseCount(Fts3Expr *pExpr){
   int nPhrase = 0;
   (void)fts3ExprIterate(pExpr, fts3ExprPhraseCountCb, (void *)&nPhrase);
   return nPhrase;
 }
 
 /*
 ** Advance the position list iterator specified by the first two 
@@ skipping 200 matching lines @@
   memset(sIter.aPhrase, 0, nByte);
 
   /* Initialize the contents of the SnippetIter object. Then iterate through
   ** the set of phrases in the expression to populate the aPhrase[] array.
   */
   sIter.pCsr = pCsr;
   sIter.iCol = iCol;
   sIter.nSnippet = nSnippet;
   sIter.nPhrase = nList;
   sIter.iCurrent = -1;
-  (void)fts3ExprIterate(pCsr->pExpr, fts3SnippetFindPositions, (void *)&sIter);
+  rc = fts3ExprIterate(pCsr->pExpr, fts3SnippetFindPositions, (void*)&sIter);
+  if( rc==SQLITE_OK ){
 
-  /* Set the *pmSeen output variable. */
-  for(i=0; i<nList; i++){
-    if( sIter.aPhrase[i].pHead ){
-      *pmSeen |= (u64)1 << i;
+    /* Set the *pmSeen output variable. */
+    for(i=0; i<nList; i++){
+      if( sIter.aPhrase[i].pHead ){
+        *pmSeen |= (u64)1 << i;
+      }
     }
+
+    /* Loop through all candidate snippets. Store the best snippet in 
+     ** *pFragment. Store its associated 'score' in iBestScore.
+     */
+    pFragment->iCol = iCol;
+    while( !fts3SnippetNextCandidate(&sIter) ){
+      int iPos;
+      int iScore;
+      u64 mCover;
+      u64 mHighlite;
+      fts3SnippetDetails(&sIter, mCovered, &iPos, &iScore, &mCover,&mHighlite);
+      assert( iScore>=0 );
+      if( iScore>iBestScore ){
+        pFragment->iPos = iPos;
+        pFragment->hlmask = mHighlite;
+        pFragment->covered = mCover;
+        iBestScore = iScore;
+      }
+    }
+
+    *piScore = iBestScore;
   }
-
-  /* Loop through all candidate snippets. Store the best snippet in 
-  ** *pFragment. Store its associated 'score' in iBestScore.
-  */
-  pFragment->iCol = iCol;
-  while( !fts3SnippetNextCandidate(&sIter) ){
-    int iPos;
-    int iScore;
-    u64 mCover;
-    u64 mHighlight;
-    fts3SnippetDetails(&sIter, mCovered, &iPos, &iScore, &mCover, &mHighlight);
-    assert( iScore>=0 );
-    if( iScore>iBestScore ){
-      pFragment->iPos = iPos;
-      pFragment->hlmask = mHighlight;
-      pFragment->covered = mCover;
-      iBestScore = iScore;
-    }
-  }
-
   sqlite3_free(sIter.aPhrase);
-  *piScore = iBestScore;
-  return SQLITE_OK;
+  return rc;
 }
 
 
 /*
 ** Append a string to the string-buffer passed as the first argument.
 **
 ** If nAppend is negative, then the length of the string zAppend is
 ** determined using strlen().
 */
 static int fts3StringAppend(
@@ skipping 187 matching lines @@
       int n = nDoc - iBegin;
       rc = fts3SnippetShift(
           pTab, pCsr->iLangid, nSnippet, &zDoc[iBegin], n, &iPos, &hlmask
       );
       isShiftDone = 1;
 
       /* Now that the shift has been done, check if the initial "..." are
       ** required. They are required if (a) this is not the first fragment,
       ** or (b) this fragment does not begin at position 0 of its column. 
       */
-      if( rc==SQLITE_OK && (iPos>0 || iFragment>0) ){
-        rc = fts3StringAppend(pOut, zEllipsis, -1);
+      if( rc==SQLITE_OK ){
+        if( iPos>0 || iFragment>0 ){
+          rc = fts3StringAppend(pOut, zEllipsis, -1);
+        }else if( iBegin ){
+          rc = fts3StringAppend(pOut, zDoc, iBegin);
+        }
       }
       if( rc!=SQLITE_OK || iCurrent<iPos ) continue;
     }
 
     if( iCurrent>=(iPos+nSnippet) ){
       if( isLast ){
         rc = fts3StringAppend(pOut, zEllipsis, -1);
       }
       break;
     }
@@ skipping 36 matching lines @@
   while( 0xFE & (*pEnd | c) ){
     c = *pEnd++ & 0x80;
     if( !c ) nEntry++;
   }
 
   *ppCollist = pEnd;
   return nEntry;
 }
 
 /*
+** This function gathers 'y' or 'b' data for a single phrase.
+*/
+static void fts3ExprLHits(
+  Fts3Expr *pExpr,                /* Phrase expression node */
+  MatchInfo *p                    /* Matchinfo context */
+){
+  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 = pExpr->iPhrase * p->nCol;
+  }else{
+    iStart = pExpr->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);
+  }
+}
+
+/*
+** Gather the results for matchinfo directives 'y' and 'b'.
+*/
+static void fts3ExprLHitGather(
+  Fts3Expr *pExpr,
+  MatchInfo *p
+){
+  assert( (pExpr->pLeft==0)==(pExpr->pRight==0) );
+  if( pExpr->bEof==0 && pExpr->iDocid==p->pCursor->iPrevId ){
+    if( pExpr->pLeft ){
+      fts3ExprLHitGather(pExpr->pLeft, p);
+      fts3ExprLHitGather(pExpr->pRight, p);
+    }else{
+      fts3ExprLHits(pExpr, p);
+    }
+  }
+}
+
+/*
 ** fts3ExprIterate() callback used to collect the "global" matchinfo stats
 ** for a single query. 
 **
 ** fts3ExprIterate() callback to load the 'global' elements of a
 ** FTS3_MATCHINFO_HITS matchinfo array. The global stats are those elements 
 ** of the matchinfo array that are constant for all rows returned by the 
 ** current query.
 **
 ** Argument pCtx is actually a pointer to a struct of type MatchInfo. This
 ** function populates Matchinfo.aMatchinfo[] as follows:
@@ skipping 57 matching lines @@
   char cArg,
   char **pzErr
 ){
   if( (cArg==FTS3_MATCHINFO_NPHRASE)
    || (cArg==FTS3_MATCHINFO_NCOL)
    || (cArg==FTS3_MATCHINFO_NDOC && pTab->bFts4)
    || (cArg==FTS3_MATCHINFO_AVGLENGTH && pTab->bFts4)
    || (cArg==FTS3_MATCHINFO_LENGTH && pTab->bHasDocsize)
    || (cArg==FTS3_MATCHINFO_LCS)
    || (cArg==FTS3_MATCHINFO_HITS)
+   || (cArg==FTS3_MATCHINFO_LHITS)
+   || (cArg==FTS3_MATCHINFO_LHITS_BM)
   ){
     return SQLITE_OK;
   }
-  *pzErr = sqlite3_mprintf("unrecognized matchinfo request: %c", cArg);
+  sqlite3Fts3ErrMsg(pzErr, "unrecognized matchinfo request: %c", cArg);
   return SQLITE_ERROR;
 }
 
 static int fts3MatchinfoSize(MatchInfo *pInfo, char cArg){
   int nVal;                       /* Number of integers output by cArg */
 
   switch( cArg ){
     case FTS3_MATCHINFO_NDOC:
     case FTS3_MATCHINFO_NPHRASE: 
     case FTS3_MATCHINFO_NCOL: 
       nVal = 1;
       break;
 
     case FTS3_MATCHINFO_AVGLENGTH:
     case FTS3_MATCHINFO_LENGTH:
     case FTS3_MATCHINFO_LCS:
       nVal = pInfo->nCol;
       break;
 
+    case FTS3_MATCHINFO_LHITS:
+      nVal = pInfo->nCol * pInfo->nPhrase;
+      break;
+
+    case FTS3_MATCHINFO_LHITS_BM:
+      nVal = pInfo->nPhrase * ((pInfo->nCol + 31) / 32);
+      break;
+
     default:
       assert( cArg==FTS3_MATCHINFO_HITS );
       nVal = pInfo->nCol * pInfo->nPhrase * 3;
       break;
   }
 
   return nVal;
 }
 
 static int fts3MatchinfoSelectDoctotal(
@@ skipping 174 matching lines @@
   int bGlobal,                    /* True to grab the global stats */
   MatchInfo *pInfo,               /* Matchinfo context object */
   const char *zArg                /* Matchinfo format string */
 ){
   int rc = SQLITE_OK;
   int i;
   Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
   sqlite3_stmt *pSelect = 0;
 
   for(i=0; rc==SQLITE_OK && zArg[i]; i++){
-
+    pInfo->flag = zArg[i];
     switch( zArg[i] ){
       case FTS3_MATCHINFO_NPHRASE:
         if( bGlobal ) pInfo->aMatchinfo[0] = pInfo->nPhrase;
         break;
 
       case FTS3_MATCHINFO_NCOL:
         if( bGlobal ) pInfo->aMatchinfo[0] = pInfo->nCol;
         break;
         
       case FTS3_MATCHINFO_NDOC:
@@ skipping 39 matching lines @@
         break;
       }
 
       case FTS3_MATCHINFO_LCS:
         rc = fts3ExprLoadDoclists(pCsr, 0, 0);
         if( rc==SQLITE_OK ){
           rc = fts3MatchinfoLcs(pCsr, pInfo);
         }
         break;
 
+      case FTS3_MATCHINFO_LHITS_BM:
+      case FTS3_MATCHINFO_LHITS: {
+        int nZero = fts3MatchinfoSize(pInfo, zArg[i]) * sizeof(u32);
+        memset(pInfo->aMatchinfo, 0, nZero);
+        fts3ExprLHitGather(pCsr->pExpr, pInfo);
+        break;
+      }
+
       default: {
         Fts3Expr *pExpr;
         assert( zArg[i]==FTS3_MATCHINFO_HITS );
         pExpr = pCsr->pExpr;
         rc = fts3ExprLoadDoclists(pCsr, 0, 0);
         if( rc!=SQLITE_OK ) break;
         if( bGlobal ){
           if( pCsr->pDeferred ){
             rc = fts3MatchinfoSelectDoctotal(pTab, &pSelect, &pInfo->nDoc, 0);
             if( rc!=SQLITE_OK ) break;
           }
           rc = fts3ExprIterate(pExpr, fts3ExprGlobalHitsCb,(void*)pInfo);
+          sqlite3Fts3EvalTestDeferred(pCsr, &rc);
           if( rc!=SQLITE_OK ) break;
         }
         (void)fts3ExprIterate(pExpr, fts3ExprLocalHitsCb,(void*)pInfo);
         break;
       }
     }
 
     pInfo->aMatchinfo += fts3MatchinfoSize(pInfo, zArg[i]);
   }
 
   sqlite3_reset(pSelect);
   return rc;
 }
 
 
 /*
 ** Populate pCsr->aMatchinfo[] with data for the current row. The 
 ** 'matchinfo' data is an array of 32-bit unsigned integers (C type u32).
 */
-static int fts3GetMatchinfo(
+static void fts3GetMatchinfo(
+  sqlite3_context *pCtx,        /* Return results here */
   Fts3Cursor *pCsr,               /* FTS3 Cursor object */
   const char *zArg                /* Second argument to matchinfo() function */
 ){
   MatchInfo sInfo;
   Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
   int rc = SQLITE_OK;
   int bGlobal = 0;                /* Collect 'global' stats as well as local */
 
+  u32 *aOut = 0;
+  void (*xDestroyOut)(void*) = 0;
+
   memset(&sInfo, 0, sizeof(MatchInfo));
   sInfo.pCursor = pCsr;
   sInfo.nCol = pTab->nColumn;
 
   /* If there is cached matchinfo() data, but the format string for the 
   ** cache does not match the format string for this request, discard 
   ** the cached data. */
-  if( pCsr->zMatchinfo && strcmp(pCsr->zMatchinfo, zArg) ){
-    assert( pCsr->aMatchinfo );
-    sqlite3_free(pCsr->aMatchinfo);
-    pCsr->zMatchinfo = 0;
-    pCsr->aMatchinfo = 0;
+  if( pCsr->pMIBuffer && strcmp(pCsr->pMIBuffer->zMatchinfo, zArg) ){
+    sqlite3Fts3MIBufferFree(pCsr->pMIBuffer);
+    pCsr->pMIBuffer = 0;
   }
 
-  /* If Fts3Cursor.aMatchinfo[] is NULL, then this is the first time the
+  /* If Fts3Cursor.pMIBuffer is NULL, then this is the first time the
   ** matchinfo function has been called for this query. In this case 
   ** allocate the array used to accumulate the matchinfo data and
   ** initialize those elements that are constant for every row.
   */
-  if( pCsr->aMatchinfo==0 ){
+  if( pCsr->pMIBuffer==0 ){
     int nMatchinfo = 0;           /* Number of u32 elements in match-info */
-    int nArg;                     /* Bytes in zArg */
     int i;                        /* Used to iterate through zArg */
 
     /* Determine the number of phrases in the query */
     pCsr->nPhrase = fts3ExprPhraseCount(pCsr->pExpr);
     sInfo.nPhrase = pCsr->nPhrase;
 
     /* Determine the number of integers in the buffer returned by this call. */
     for(i=0; zArg[i]; i++){
+      char *zErr = 0;
+      if( fts3MatchinfoCheck(pTab, zArg[i], &zErr) ){
+        sqlite3_result_error(pCtx, zErr, -1);
+        sqlite3_free(zErr);
+        return;
+      }
       nMatchinfo += fts3MatchinfoSize(&sInfo, zArg[i]);
     }
 
     /* Allocate space for Fts3Cursor.aMatchinfo[] and Fts3Cursor.zMatchinfo. */
-    nArg = (int)strlen(zArg);
-    pCsr->aMatchinfo = (u32 *)sqlite3_malloc(sizeof(u32)*nMatchinfo + nArg + 1);
-    if( !pCsr->aMatchinfo ) return SQLITE_NOMEM;
+    pCsr->pMIBuffer = fts3MIBufferNew(nMatchinfo, zArg);
+    if( !pCsr->pMIBuffer ) rc = SQLITE_NOMEM;
 
-    pCsr->zMatchinfo = (char *)&pCsr->aMatchinfo[nMatchinfo];
-    pCsr->nMatchinfo = nMatchinfo;
-    memcpy(pCsr->zMatchinfo, zArg, nArg+1);
-    memset(pCsr->aMatchinfo, 0, sizeof(u32)*nMatchinfo);
     pCsr->isMatchinfoNeeded = 1;
     bGlobal = 1;
   }
 
-  sInfo.aMatchinfo = pCsr->aMatchinfo;
-  sInfo.nPhrase = pCsr->nPhrase;
-  if( pCsr->isMatchinfoNeeded ){
-    rc = fts3MatchinfoValues(pCsr, bGlobal, &sInfo, zArg);
-    pCsr->isMatchinfoNeeded = 0;
+  if( rc==SQLITE_OK ){
+    xDestroyOut = fts3MIBufferAlloc(pCsr->pMIBuffer, &aOut);
+    if( xDestroyOut==0 ){
+      rc = SQLITE_NOMEM;
+    }
   }
 
-  return rc;
+  if( rc==SQLITE_OK ){
+    sInfo.aMatchinfo = aOut;
+    sInfo.nPhrase = pCsr->nPhrase;
+    rc = fts3MatchinfoValues(pCsr, bGlobal, &sInfo, zArg);
+    if( bGlobal ){
+      fts3MIBufferSetGlobal(pCsr->pMIBuffer);
+    }
+  }
+
+  if( rc!=SQLITE_OK ){
+    sqlite3_result_error_code(pCtx, rc);
+    if( xDestroyOut ) xDestroyOut(aOut);
+  }else{
+    int n = pCsr->pMIBuffer->nElem * sizeof(u32);
+    sqlite3_result_blob(pCtx, aOut, n, xDestroyOut);
+  }
 }
 
 /*
 ** Implementation of snippet() function.
 */
 void sqlite3Fts3Snippet(
   sqlite3_context *pCtx,          /* SQLite function call context */
   Fts3Cursor *pCsr,               /* Cursor object */
   const char *zStart,             /* Snippet start text - "<b>" */
   const char *zEnd,               /* Snippet end text - "</b>" */
@@ skipping 41 matching lines @@
       SnippetFragment *pFragment = &aSnippet[iSnip];
 
       memset(pFragment, 0, sizeof(*pFragment));
 
       /* Loop through all columns of the table being considered for snippets.
       ** If the iCol argument to this function was negative, this means all
       ** columns of the FTS3 table. Otherwise, only column iCol is considered.
       */
       for(iRead=0; iRead<pTab->nColumn; iRead++){
         SnippetFragment sF = {0, 0, 0, 0};
-        int iS;
+        int iS = 0;
         if( iCol>=0 && iRead!=iCol ) continue;
 
         /* Find the best snippet of nFToken tokens in column iRead. */
         rc = fts3BestSnippet(nFToken, pCsr, iRead, mCovered, &mSeen, &sF, &iS);
         if( rc!=SQLITE_OK ){
           goto snippet_out;
         }
         if( iS>iBestScore ){
           *pFragment = sF;
           iBestScore = iS;
@@ skipping 123 matching lines @@
     int iCurrent = 0;
     const char *zDoc;
     int nDoc;
 
     /* Initialize the contents of sCtx.aTerm[] for column iCol. There is 
     ** no way that this operation can fail, so the return code from
     ** fts3ExprIterate() can be discarded.
     */
     sCtx.iCol = iCol;
     sCtx.iTerm = 0;
-    (void)fts3ExprIterate(pCsr->pExpr, fts3ExprTermOffsetInit, (void *)&sCtx);
+    (void)fts3ExprIterate(pCsr->pExpr, fts3ExprTermOffsetInit, (void*)&sCtx);
 
     /* Retreive the text stored in column iCol. If an SQL NULL is stored 
     ** in column iCol, jump immediately to the next iteration of the loop.
     ** If an OOM occurs while retrieving the data (this can happen if SQLite
     ** needs to transform the data from utf-16 to utf-8), return SQLITE_NOMEM 
     ** to the caller. 
     */
     zDoc = (const char *)sqlite3_column_text(pCsr->pStmt, iCol+1);
     nDoc = sqlite3_column_bytes(pCsr->pStmt, iCol+1);
     if( zDoc==0 ){
@@ skipping 71 matching lines @@
 
 /*
 ** Implementation of matchinfo() function.
 */
 void sqlite3Fts3Matchinfo(
   sqlite3_context *pContext,      /* Function call context */
   Fts3Cursor *pCsr,               /* FTS3 table cursor */
   const char *zArg                /* Second arg to matchinfo() function */
 ){
   Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
-  int rc;
-  int i;
   const char *zFormat;
 
   if( zArg ){
-    for(i=0; zArg[i]; i++){
-      char *zErr = 0;
-      if( fts3MatchinfoCheck(pTab, zArg[i], &zErr) ){
-        sqlite3_result_error(pContext, zErr, -1);
-        sqlite3_free(zErr);
-        return;
-      }
-    }
     zFormat = zArg;
   }else{
     zFormat = FTS3_MATCHINFO_DEFAULT;
   }
 
   if( !pCsr->pExpr ){
     sqlite3_result_blob(pContext, "", 0, SQLITE_STATIC);
     return;
-  }
-
-  /* Retrieve matchinfo() data. */
-  rc = fts3GetMatchinfo(pCsr, zFormat);
-  sqlite3Fts3SegmentsClose(pTab);
-
-  if( rc!=SQLITE_OK ){
-    sqlite3_result_error_code(pContext, rc);
   }else{
-    int n = pCsr->nMatchinfo * sizeof(u32);
-    sqlite3_result_blob(pContext, pCsr->aMatchinfo, n, SQLITE_TRANSIENT);
+    /* Retrieve matchinfo() data. */
+    fts3GetMatchinfo(pContext, pCsr, zFormat);
+    sqlite3Fts3SegmentsClose(pTab);
   }
 }
 
 #endif