Lemon update 2015-09-07 19:52:55 on branch lemon-update

- Change the parser engine so that it (once again) waits for a lookahead token before reducing, even in a SHIFTREDUCE action. (user: drh)

tools/lemon/lempar.c

@@ -170,9 +170,13 @@ static const YYCODETYPE yyFallback[] = {
 **   +  The semantic value stored at this level of the stack.  This is
 **      the information used by the action routines in the grammar.
 **      It is sometimes called the "minor" token.
+**
+** After the "shift" half of a SHIFTREDUCE action, the stateno field
+** actually contains the reduce action for the second half of the
+** SHIFTREDUCE.
 */
 struct yyStackEntry {
-  YYACTIONTYPE stateno;  /* The state-number */
+  YYACTIONTYPE stateno;  /* The state-number, or reduce action in SHIFTREDUCE */
   YYCODETYPE major;      /* The major token value.  This is the code
                          ** number for the token at this stack level */
   YYMINORTYPE minor;     /* The user-supplied minor token value.  This
@@ -401,6 +405,7 @@ static int yy_find_shift_action(
   int i;
   int stateno = pParser->yystack[pParser->yyidx].stateno;
 
+  if( stateno>=YY_MIN_REDUCE ) return stateno; 
   if( stateno>YY_SHIFT_COUNT
    || (i = yy_shift_ofst[stateno])==YY_SHIFT_USE_DFLT ){
     return yy_default[stateno];
@@ -504,10 +509,32 @@ static void yyStackOverflow(yyParser *yypParser, YYMINORTYPE *yypMinor){
    ParseARG_STORE; /* Suppress warning about unused %extra_argument var */
 }
 
+/*
+** Print tracing information for a SHIFT action
+*/
+#ifndef NDEBUG
+static void yyTraceShift(yyParser *yypParser, int yyNewState){
+  if( yyTraceFILE ){
+    int i;
+    if( yyNewState<YYNSTATE ){
+      fprintf(yyTraceFILE,"%sShift %d\n",yyTracePrompt,yyNewState);
+      fprintf(yyTraceFILE,"%sStack:",yyTracePrompt);
+      for(i=1; i<=yypParser->yyidx; i++)
+        fprintf(yyTraceFILE," %s",yyTokenName[yypParser->yystack[i].major]);
+      fprintf(yyTraceFILE,"\n");
+    }else{
+      fprintf(yyTraceFILE,"%sShift *\n",yyTracePrompt);
+    }
+  }
+}
+#else
+# define yyTraceShift(X,Y)
+#endif
+
 /*
 ** Perform a shift action.  Return the number of errors.
 */
-static int yy_shift(
+static void yy_shift(
   yyParser *yypParser,          /* The parser to be shifted */
   int yyNewState,               /* The new state to shift in */
   int yyMajor,                  /* The major token to shift in */
@@ -523,14 +550,14 @@ static int yy_shift(
 #if YYSTACKDEPTH>0
   if( yypParser->yyidx>=YYSTACKDEPTH ){
     yyStackOverflow(yypParser, yypMinor);
-    return 1;
+    return;
   }
 #else
   if( yypParser->yyidx>=yypParser->yystksz ){
     yyGrowStack(yypParser);
     if( yypParser->yyidx>=yypParser->yystksz ){
       yyStackOverflow(yypParser, yypMinor);
-      return 1;
+      return;
     }
   }
 #endif
@@ -538,21 +565,7 @@ static int yy_shift(
   yytos->stateno = (YYACTIONTYPE)yyNewState;
   yytos->major = (YYCODETYPE)yyMajor;
   yytos->minor = *yypMinor;
-#ifndef NDEBUG
+  yyTraceShift(yypParser, yyNewState);
-  if( yyTraceFILE && yypParser->yyidx>0 ){
-    int i;
-    if( yyNewState<YYNSTATE ){
-      fprintf(yyTraceFILE,"%sShift %d\n",yyTracePrompt,yyNewState);
-      fprintf(yyTraceFILE,"%sStack:",yyTracePrompt);
-      for(i=1; i<=yypParser->yyidx; i++)
-        fprintf(yyTraceFILE," %s",yyTokenName[yypParser->yystack[i].major]);
-      fprintf(yyTraceFILE,"\n");
-    }else{
-      fprintf(yyTraceFILE,"%sShift *\n",yyTracePrompt);
-    }
-  }
-#endif
-  return 0;
 }
 
 /* The following table contains information about every rule that
@@ -623,7 +636,8 @@ static void yy_reduce(
   yysize = yyRuleInfo[yyruleno].nrhs;
   yypParser->yyidx -= yysize;
   yyact = yy_find_reduce_action(yymsp[-yysize].stateno,(YYCODETYPE)yygoto);
-  if( yyact < YY_MAX_SHIFTREDUCE ){
+  if( yyact <= YY_MAX_SHIFTREDUCE ){
+    if( yyact>YY_MAX_SHIFT ) yyact += YY_MIN_REDUCE - YY_MIN_SHIFTREDUCE;
     /* If the reduce action popped at least
     ** one element off the stack, then we can push the new element back
     ** onto the stack here, and skip the stack overflow test in yy_shift().
@@ -634,16 +648,9 @@ static void yy_reduce(
       yymsp->stateno = (YYACTIONTYPE)yyact;
       yymsp->major = (YYCODETYPE)yygoto;
       yymsp->minor = yygotominor;
-#ifndef NDEBUG
+      yyTraceShift(yypParser, yyact);
-      if( yyTraceFILE ){
-        fprintf(yyTraceFILE,"%sShift %d\n",yyTracePrompt,yyact);
-      }
-#endif
     }else{
-      if( yy_shift(yypParser,yyact,yygoto,&yygotominor) ) yyact = 0;
+      yy_shift(yypParser,yyact,yygoto,&yygotominor);
-    }
-    if( yyact>=YY_MIN_SHIFTREDUCE ){
-      yy_reduce(yypParser, yyact - YY_MIN_SHIFTREDUCE);
     }
   }else{
     assert( yyact == YY_ACCEPT_ACTION );
@@ -767,13 +774,10 @@ void Parse(
   do{
     yyact = yy_find_shift_action(yypParser,(YYCODETYPE)yymajor);
     if( yyact <= YY_MAX_SHIFTREDUCE ){
-      if( yy_shift(yypParser,yyact,yymajor,&yyminorunion)==0 ){
+      if( yyact > YY_MAX_SHIFT ) yyact += YY_MIN_REDUCE - YY_MIN_SHIFTREDUCE;
+      yy_shift(yypParser,yyact,yymajor,&yyminorunion);
       yypParser->yyerrcnt--;
       yymajor = YYNOCODE;
-        if( yyact > YY_MAX_SHIFT ){
-          yy_reduce(yypParser, yyact-YY_MIN_SHIFTREDUCE);
-        }
-      }
     }else if( yyact <= YY_MAX_REDUCE ){
       yy_reduce(yypParser,yyact-YY_MIN_REDUCE);
     }else{