1 files changed, 84 insertions, 31 deletions

diff --git a/ext/fts5/fts5_expr.c b/ext/fts5/fts5_expr.c
index 3a1497f05..7c8e3c87c 100644
--- a/ext/fts5/fts5_expr.c
+++ b/ext/fts5/fts5_expr.c
@@ -62,6 +62,9 @@ struct Fts5ExprNode {
   int bEof;                       /* True at EOF */
   int bNomatch;                   /* True if entry is not a match */
 
+  /* Next method for this node. */
+  int (*xNext)(Fts5Expr*, Fts5ExprNode*, int, i64);
+
   i64 iRowid;                     /* Current rowid */
   Fts5ExprNearset *pNear;         /* For FTS5_STRING - cluster of phrases */
 
@@ -74,6 +77,12 @@ struct Fts5ExprNode {
 #define Fts5NodeIsString(p) ((p)->eType==FTS5_TERM || (p)->eType==FTS5_STRING)
 
 /*
+** Invoke the xNext method of an Fts5ExprNode object. This macro should be
+** used as if it has the same signature as the xNext() methods themselves.
+*/
+#define fts5ExprNodeNext(a,b,c,d) (b)->xNext((a), (b), (c), (d))
+
+/*
 ** An instance of the following structure represents a single search term
 ** or term prefix.
 */
@@ -234,7 +243,15 @@ int sqlite3Fts5ExprNew(
       sParse.rc = SQLITE_NOMEM;
       sqlite3Fts5ParseNodeFree(sParse.pExpr);
     }else{
-      pNew->pRoot = sParse.pExpr;
+      if( !sParse.pExpr ){
+        const int nByte = sizeof(Fts5ExprNode);
+        pNew->pRoot = (Fts5ExprNode*)sqlite3Fts5MallocZero(&sParse.rc, nByte);
+        if( pNew->pRoot ){
+          pNew->pRoot->bEof = 1;
+        }
+      }else{
+        pNew->pRoot = sParse.pExpr;
+      }
       pNew->pIndex = 0;
       pNew->pConfig = pConfig;
       pNew->apExprPhrase = sParse.apPhrase;
@@ -500,12 +517,6 @@ static int fts5LookaheadReaderInit(
   return fts5LookaheadReaderNext(p);
 }
 
-#if 0
-static int fts5LookaheadReaderEof(Fts5LookaheadReader *p){
-  return (p->iPos==FTS5_LOOKAHEAD_EOF);
-}
-#endif
-
 typedef struct Fts5NearTrimmer Fts5NearTrimmer;
 struct Fts5NearTrimmer {
   Fts5LookaheadReader reader;     /* Input iterator */
@@ -636,6 +647,7 @@ static int fts5ExprNearAdvanceFirst(
   Fts5ExprTerm *pTerm = &pNode->pNear->apPhrase[0]->aTerm[0];
   int rc = SQLITE_OK;
 
+  pNode->bNomatch = 0;
   if( pTerm->pSynonym ){
     int bEof = 1;
     Fts5ExprTerm *p;
@@ -765,17 +777,6 @@ static int fts5ExprNearTest(
     for(pTerm=&pPhrase->aTerm[0]; pTerm; pTerm=pTerm->pSynonym){
       Fts5IndexIter *pIter = pTerm->pIter;
       if( sqlite3Fts5IterEof(pIter)==0 ){
-#if 0
-        int n;
-        i64 iRowid;
-        rc = sqlite3Fts5IterPoslist(pIter, pNear->pColset, 0, &n, &iRowid);
-        if( rc!=SQLITE_OK ){
-          *pRc = rc;
-          return 0;
-        }else if( iRowid==pNode->iRowid && n>0 ){
-          pPhrase->poslist.n = 1;
-        }
-#endif
         if( pIter->iRowid==pNode->iRowid && pIter->nData>0 ){
           pPhrase->poslist.n = 1;
         }
@@ -797,11 +798,6 @@ static int fts5ExprNearTest(
       }else{
         Fts5IndexIter *pIter = pPhrase->aTerm[0].pIter;
         fts5BufferSet(&rc, &pPhrase->poslist, pIter->nData, pIter->pData);
-#if 0
-        rc = sqlite3Fts5IterPoslistBuffer(
-            pPhrase->aTerm[0].pIter, &pPhrase->poslist
-        );
-#endif
       }
     }
 
@@ -888,6 +884,7 @@ static int fts5ExprNearNextMatch(
           if( iRowid==iLast ) continue;
           bMatch = 0;
           if( fts5ExprSynonymAdvanceto(pTerm, bDesc, &iLast, &rc) ){
+            pNode->bNomatch = 0;
             pNode->bEof = 1;
             return rc;
           }
@@ -905,7 +902,8 @@ static int fts5ExprNearNextMatch(
   }while( bMatch==0 );
 
   pNode->iRowid = iLast;
-  pNode->bNomatch = (0==fts5ExprNearTest(&rc, pExpr, pNode));
+  pNode->bNomatch = ((0==fts5ExprNearTest(&rc, pExpr, pNode)) && rc==SQLITE_OK);
+  assert( pNode->bEof==0 || pNode->bNomatch==0 );
 
   return rc;
 }
@@ -923,6 +921,7 @@ static int fts5ExprNearInitAll(
   int i, j;
   int rc = SQLITE_OK;
 
+  assert( pNode->bNomatch==0 );
   for(i=0; rc==SQLITE_OK && i<pNear->nPhrase; i++){
     Fts5ExprPhrase *pPhrase = pNear->apPhrase[i];
     for(j=0; j<pPhrase->nTerm; j++){
@@ -990,6 +989,7 @@ static int fts5RowidCmp(
 static void fts5ExprSetEof(Fts5ExprNode *pNode){
   int i;
   pNode->bEof = 1;
+  pNode->bNomatch = 0;
   for(i=0; i<pNode->nChild; i++){
     fts5ExprSetEof(pNode->apChild[i]);
   }
@@ -1012,8 +1012,6 @@ static void fts5ExprNodeZeroPoslist(Fts5ExprNode *pNode){
 }
 
 
-static int fts5ExprNodeNext(Fts5Expr*, Fts5ExprNode*, int, i64);
-
 /*
 ** Argument pNode is an FTS5_AND node.
 */
@@ -1094,13 +1092,40 @@ static int fts5NodeCompare(
 }
 
 /*
+** xNext() method for a node of type FTS5_TERM.
+*/
+static int fts5ExprNodeNext_Term(
+  Fts5Expr *pExpr, 
+  Fts5ExprNode *pNode,
+  int bFromValid,
+  i64 iFrom
+){
+  int rc;
+  Fts5IndexIter *pIter = pNode->pNear->apPhrase[0]->aTerm[0].pIter;
+
+  assert( pNode->bEof==0 );
+  if( bFromValid ){
+    rc = sqlite3Fts5IterNextFrom(pIter, iFrom);
+  }else{
+    rc = sqlite3Fts5IterNext(pIter);
+  }
+  if( rc==SQLITE_OK && sqlite3Fts5IterEof(pIter)==0 ){
+    rc = fts5ExprTokenTest(pExpr, pNode);
+  }else{
+    pNode->bEof = 1;
+    pNode->bNomatch = 0;
+  }
+  return rc;
+}
+
+/*
 ** Advance node iterator pNode, part of expression pExpr. If argument
 ** bFromValid is zero, then pNode is advanced exactly once. Or, if argument
 ** bFromValid is non-zero, then pNode is advanced until it is at or past
 ** rowid value iFrom. Whether "past" means "less than" or "greater than"
 ** depends on whether this is an ASC or DESC iterator.
 */
-static int fts5ExprNodeNext(
+static int fts5ExprNodeNext_Fallback(
   Fts5Expr *pExpr, 
   Fts5ExprNode *pNode,
   int bFromValid,
@@ -1127,6 +1152,7 @@ static int fts5ExprNodeNext(
           rc = fts5ExprTokenTest(pExpr, pNode);
         }else{
           pNode->bEof = 1;
+          pNode->bNomatch = 0;
         }
         return rc;
       };
@@ -1180,6 +1206,7 @@ static int fts5ExprNodeNext(
       || pNode->iRowid==iFrom || pExpr->bDesc==(pNode->iRowid<iFrom)    /* c */
   );
 
+  assert( pNode->bNomatch==0 || rc==SQLITE_OK );
   return rc;
 }
 
@@ -1246,6 +1273,7 @@ static int fts5ExprNodeNextMatch(
           rc = fts5ExprNodeNext(pExpr, p1, 0, 0);
         }
         pNode->bEof = p1->bEof;
+        pNode->bNomatch = p1->bNomatch;
         pNode->iRowid = p1->iRowid;
         if( p1->bEof ){
           fts5ExprNodeZeroPoslist(p2);
@@ -1268,16 +1296,36 @@ static int fts5ExprNodeNextMatch(
 static int fts5ExprNodeFirst(Fts5Expr *pExpr, Fts5ExprNode *pNode){
   int rc = SQLITE_OK;
   pNode->bEof = 0;
+  pNode->bNomatch = 0;
 
   if( Fts5NodeIsString(pNode) ){
     /* Initialize all term iterators in the NEAR object. */
     rc = fts5ExprNearInitAll(pExpr, pNode);
   }else{
     int i;
+    int nEof = 0;
     for(i=0; i<pNode->nChild && rc==SQLITE_OK; i++){
+      Fts5ExprNode *pChild = pNode->apChild[i];
       rc = fts5ExprNodeFirst(pExpr, pNode->apChild[i]);
+      assert( pChild->bEof==0 || pChild->bEof==1 );
+      nEof += pChild->bEof;
     }
     pNode->iRowid = pNode->apChild[0]->iRowid;
+
+    switch( pNode->eType ){
+      case FTS5_AND:
+        if( nEof>0 ) fts5ExprSetEof(pNode);
+        break;
+
+      case FTS5_OR:
+        if( pNode->nChild==nEof ) fts5ExprSetEof(pNode);
+        break;
+
+      default:
+        assert( pNode->eType==FTS5_NOT );
+        pNode->bEof = pNode->apChild[0]->bEof;
+        break;
+    }
   }
 
   if( rc==SQLITE_OK ){
@@ -1305,7 +1353,7 @@ static int fts5ExprNodeFirst(Fts5Expr *pExpr, Fts5ExprNode *pNode){
 int sqlite3Fts5ExprFirst(Fts5Expr *p, Fts5Index *pIdx, i64 iFirst, int bDesc){
   Fts5ExprNode *pRoot = p->pRoot;
   int rc = SQLITE_OK;
-  if( pRoot ){
+  if( pRoot->xNext ){
     p->pIndex = pIdx;
     p->bDesc = bDesc;
     rc = fts5ExprNodeFirst(p, pRoot);
@@ -1333,9 +1381,11 @@ int sqlite3Fts5ExprFirst(Fts5Expr *p, Fts5Index *pIdx, i64 iFirst, int bDesc){
 int sqlite3Fts5ExprNext(Fts5Expr *p, i64 iLast){
   int rc;
   Fts5ExprNode *pRoot = p->pRoot;
+  assert( pRoot->bEof==0 && pRoot->bNomatch==0 );
   do {
     rc = fts5ExprNodeNext(p, pRoot, 0, 0);
-  }while( pRoot->bNomatch && pRoot->bEof==0 && rc==SQLITE_OK );
+    assert( pRoot->bNomatch==0 || (rc==SQLITE_OK && pRoot->bEof==0) );
+  }while( pRoot->bNomatch );
   if( fts5RowidCmp(p, pRoot->iRowid, iLast)>0 ){
     pRoot->bEof = 1;
   }
@@ -1343,7 +1393,7 @@ int sqlite3Fts5ExprNext(Fts5Expr *p, i64 iLast){
 }
 
 int sqlite3Fts5ExprEof(Fts5Expr *p){
-  return (p->pRoot==0 || p->pRoot->bEof);
+  return p->pRoot->bEof;
 }
 
 i64 sqlite3Fts5ExprRowid(Fts5Expr *p){
@@ -1640,6 +1690,7 @@ int sqlite3Fts5ExprClonePhrase(
     pNew->apExprPhrase[0] = sCtx.pPhrase;
     pNew->pRoot->pNear->apPhrase[0] = sCtx.pPhrase;
     pNew->pRoot->pNear->nPhrase = 1;
+    pNew->pRoot->xNext = fts5ExprNodeNext_Fallback;
     sCtx.pPhrase->pNode = pNew->pRoot;
 
     if( pOrig->nTerm==1 && pOrig->aTerm[0].pSynonym==0 ){
@@ -1840,6 +1891,7 @@ Fts5ExprNode *sqlite3Fts5ParseNode(
     pRet = (Fts5ExprNode*)sqlite3Fts5MallocZero(&pParse->rc, nByte);
 
     if( pRet ){
+      pRet->xNext = fts5ExprNodeNext_Fallback;
       pRet->eType = eType;
       pRet->pNear = pNear;
       if( eType==FTS5_STRING ){
@@ -1850,6 +1902,7 @@ Fts5ExprNode *sqlite3Fts5ParseNode(
         if( pNear->nPhrase==1 && pNear->apPhrase[0]->nTerm==1 ){
           if( pNear->apPhrase[0]->aTerm[0].pSynonym==0 ){
             pRet->eType = FTS5_TERM;
+            pRet->xNext = fts5ExprNodeNext_Term;
           }
         }else if( pParse->pConfig->eDetail!=FTS5_DETAIL_FULL ){
           assert( pParse->rc==SQLITE_OK );
@@ -2144,7 +2197,7 @@ static void fts5ExprFunction(
   }
   if( rc==SQLITE_OK ){
     char *zText;
-    if( pExpr->pRoot==0 ){
+    if( pExpr->pRoot->xNext==0 ){
       zText = sqlite3_mprintf("");
     }else if( bTcl ){
       zText = fts5ExprPrintTcl(pConfig, zNearsetCmd, pExpr->pRoot);