Index: src/parse.y
==================================================================
--- src/parse.y
+++ src/parse.y
@@ -214,10 +214,14 @@
   QUERY KEY OF OFFSET PRAGMA RAISE RECURSIVE RELEASE REPLACE RESTRICT ROW ROWS
   ROLLBACK SAVEPOINT TEMP TRIGGER VACUUM VIEW VIRTUAL WITH WITHOUT
 %ifdef SQLITE_OMIT_COMPOUND_SELECT
   EXCEPT INTERSECT UNION
 %endif SQLITE_OMIT_COMPOUND_SELECT
+%ifndef SQLITE_OMIT_WINDOWFUNC
+  CURRENT FILTER FOLLOWING ?OVER PARTITION 
+  PRECEDING RANGE UNBOUNDED ?WINDOW 
+%endif SQLITE_OMIT_WINDOWFUNC
   REINDEX RENAME CTIME_KW IF
   .
 %wildcard ANY.
 
 // Define operator precedence early so that this is the first occurrence

Index: tool/lemon.c
==================================================================
--- tool/lemon.c
+++ tool/lemon.c
@@ -270,10 +270,11 @@
   int dtnum;               /* The data type number.  In the parser, the value
                            ** stack is a union.  The .yy%d element of this
                            ** union is the correct data type for this object */
   int bContent;            /* True if this symbol ever carries content - if
                            ** it is ever more than just syntax */
+  int bWeakFallback;       /* True for a weak fallback */
   /* The following fields are used by MULTITERMINALs only */
   int nsubsym;             /* Number of constituent symbols in the MULTI */
   struct symbol **subsym;  /* Array of constituent symbols */
 };
 
@@ -2207,10 +2208,11 @@
   RESYNC_AFTER_RULE_ERROR,
   RESYNC_AFTER_DECL_ERROR,
   WAITING_FOR_DESTRUCTOR_SYMBOL,
   WAITING_FOR_DATATYPE_SYMBOL,
   WAITING_FOR_FALLBACK_ID,
+  WAITING_FOR_WEAK_FALLBACK_ID,
   WAITING_FOR_WILDCARD_ID,
   WAITING_FOR_CLASS_ID,
   WAITING_FOR_CLASS_TOKEN,
   WAITING_FOR_TOKEN_NAME
 };
@@ -2665,10 +2667,16 @@
         psp->errorcnt++;
         psp->state = RESYNC_AFTER_DECL_ERROR;
       }
       break;
     case WAITING_FOR_FALLBACK_ID:
+      if( x[0]=='?' ){
+        psp->state = WAITING_FOR_WEAK_FALLBACK_ID;
+        break;
+      }
+      /* Fall through */
+    case WAITING_FOR_WEAK_FALLBACK_ID:
       if( x[0]=='.' ){
         psp->state = WAITING_FOR_DECL_OR_RULE;
       }else if( !ISUPPER(x[0]) ){
         ErrorMsg(psp->filename, psp->tokenlineno,
           "%%fallback argument \"%s\" should be a token", x);
@@ -2681,10 +2689,12 @@
           ErrorMsg(psp->filename, psp->tokenlineno,
             "More than one fallback assigned to token %s", x);
           psp->errorcnt++;
         }else{
           sp->fallback = psp->fallback;
+          sp->bWeakFallback = (psp->state==WAITING_FOR_WEAK_FALLBACK_ID);
+          psp->state = WAITING_FOR_FALLBACK_ID;
           psp->gp->has_fallback = 1;
         }
       }
       break;
     case WAITING_FOR_TOKEN_NAME:
@@ -4491,10 +4501,13 @@
     lemp->tablesize += (mx+1)*szCodeType;
     for(i=0; i<=mx; i++){
       struct symbol *p = lemp->symbols[i];
       if( p->fallback==0 ){
         fprintf(out, "    0,  /* %10s => nothing */\n", p->name);
+      }else if( p->bWeakFallback ){
+        fprintf(out, " %4d,  /* %10s => %s (weak) */\n",
+          -p->fallback->index, p->name, p->fallback->name);
       }else{
         fprintf(out, "  %3d,  /* %10s => %s */\n", p->fallback->index,
           p->name, p->fallback->name);
       }
       lineno++;
@@ -5110,22 +5123,16 @@
 
   sp = Symbol_find(x);
   if( sp==0 ){
     sp = (struct symbol *)calloc(1, sizeof(struct symbol) );
     MemoryCheck(sp);
+    memset(sp, 0, sizeof(*sp));
     sp->name = Strsafe(x);
     sp->type = ISUPPER(*x) ? TERMINAL : NONTERMINAL;
-    sp->rule = 0;
-    sp->fallback = 0;
     sp->prec = -1;
     sp->assoc = UNK;
-    sp->firstset = 0;
     sp->lambda = LEMON_FALSE;
-    sp->destructor = 0;
-    sp->destLineno = 0;
-    sp->datatype = 0;
-    sp->useCnt = 0;
     Symbol_insert(sp,sp->name);
   }
   sp->useCnt++;
   return sp;
 }

Index: tool/lempar.c
==================================================================
--- tool/lempar.c
+++ tool/lempar.c
@@ -88,10 +88,11 @@
 # define INTERFACE 1
 #endif
 /************* Begin control #defines *****************************************/
 %%
 /************* End control #defines *******************************************/
+#define YY_NLOOKAHEAD ((int)(sizeof(yy_lookahead)/sizeof(yy_lookahead[0])))
 
 /* Define the yytestcase() macro to be a no-op if is not already defined
 ** otherwise.
 **
 ** Applications can choose to define yytestcase() in the %include section
@@ -170,11 +171,11 @@
 ** This feature can be used, for example, to cause some keywords in a language
 ** to revert to identifiers if they keyword does not apply in the context where
 ** it appears.
 */
 #ifdef YYFALLBACK
-static const YYCODETYPE yyFallback[] = {
+static const int yyFallback[] = {
 %%
 };
 #endif /* YYFALLBACK */
 
 /* The following structure represents a single element of the
@@ -517,28 +518,38 @@
   yycoverage[stateno][iLookAhead] = 1;
 #endif
   do{
     i = yy_shift_ofst[stateno];
     assert( i>=0 );
-    assert( i+YYNTOKEN<=(int)sizeof(yy_lookahead)/sizeof(yy_lookahead[0]) );
+    /*assert( i+YYNTOKEN<=YY_NLOOKAHEAD );*/
     assert( iLookAhead!=YYNOCODE );
     assert( iLookAhead < YYNTOKEN );
     i += iLookAhead;
-    if( yy_lookahead[i]!=iLookAhead ){
+    if( i>=YY_NLOOKAHEAD || yy_lookahead[i]!=iLookAhead
+    ){
 #ifdef YYFALLBACK
-      YYCODETYPE iFallback;            /* Fallback token */
+      int iFallback;            /* Fallback token */
       if( iLookAhead<sizeof(yyFallback)/sizeof(yyFallback[0])
-             && (iFallback = yyFallback[iLookAhead])!=0 ){
-#ifndef NDEBUG
-        if( yyTraceFILE ){
-          fprintf(yyTraceFILE, "%sFALLBACK %s => %s\n",
-             yyTracePrompt, yyTokenName[iLookAhead], yyTokenName[iFallback]);
-        }
-#endif
-        assert( yyFallback[iFallback]==0 ); /* Fallback loop must terminate */
-        iLookAhead = iFallback;
-        continue;
+       && (iFallback = yyFallback[iLookAhead])!=0
+      ){
+        if( iFallback<0 && yy_default[stateno]==YY_ERROR_ACTION ){
+          /* A weak fallback only happens if current lookahead is a
+          ** syntax error */
+          iFallback = -iFallback;
+        }
+        if( iFallback>0 ){
+          /* A strong fallback happens regardless */
+#ifndef NDEBUG
+          if( yyTraceFILE ){
+            fprintf(yyTraceFILE, "%sFALLBACK %s => %s\n",
+               yyTracePrompt, yyTokenName[iLookAhead], yyTokenName[iFallback]);
+          }
+#endif
+          assert( yyFallback[iFallback]==0 ); /* Fallback loop must terminate */
+          iLookAhead = iFallback;
+          continue;
+        }
       }
 #endif
 #ifdef YYWILDCARD
       {
         int j = i - iLookAhead + YYWILDCARD;