Lemon update 2009-11-03 19:18:32 on branch trunk

- Enhancements to lemon to generate more compact action tables and to avoid making array bounds tests that can never fail on action table calculations. (user: drh)
- Update zcc-parse.lemon: YY_SZ_ACTTAB is now YY_ACTTAB_COUNT

src/zscript/zcc-parse.lemon

@@ -90,7 +90,7 @@ static void SetNodeLine(ZCC_TreeNode *name, int line)
 		for (int j = 1; j < YYERRORSYMBOL; ++j)
 		{
 			int k = i + j;
-			if (k >= 0 && k < YY_SZ_ACTTAB && yy_lookahead[k] == j)
+			if (k >= 0 && k < YY_ACTTAB_COUNT && yy_lookahead[k] == j)
 			{
 				expecting << (expecting.IsEmpty() ? "Expecting " : " or ") << ZCCTokenName(j);
 			}

tools/lemon/lemon.c

@@ -524,21 +524,9 @@ int acttab_insert(acttab *p){
   **
   ** i is the index in p->aAction[] where p->mnLookahead is inserted.
   */
-  for(i=0; i<p->nAction+p->mnLookahead; i++){
+  for(i=p->nAction-1; i>=0; i--){
-    if( p->aAction[i].lookahead<0 ){
+    /* First look for an existing action table entry that can be reused */
-      for(j=0; j<p->nLookahead; j++){
+    if( p->aAction[i].lookahead==p->mnLookahead ){
-        k = p->aLookahead[j].lookahead - p->mnLookahead + i;
-        if( k<0 ) break;
-        if( p->aAction[k].lookahead>=0 ) break;
-      }
-      if( j<p->nLookahead ) continue;
-      for(j=0; j<p->nAction; j++){
-        if( p->aAction[j].lookahead==j+p->mnLookahead-i ) break;
-      }
-      if( j==p->nAction ){
-        break;  /* Fits in empty slots */
-      }
-    }else if( p->aAction[i].lookahead==p->mnLookahead ){
       if( p->aAction[i].action!=p->mnAction ) continue;
       for(j=0; j<p->nLookahead; j++){
         k = p->aLookahead[j].lookahead - p->mnLookahead + i;
@@ -557,6 +545,25 @@ int acttab_insert(acttab *p){
       }
     }
   }
+  if( i<0 ){
+    /* If no reusable entry is found, look for an empty slot */
+    for(i=0; i<p->nAction; i++){
+      if( p->aAction[i].lookahead<0 ){
+        for(j=0; j<p->nLookahead; j++){
+          k = p->aLookahead[j].lookahead - p->mnLookahead + i;
+          if( k<0 ) break;
+          if( p->aAction[k].lookahead>=0 ) break;
+        }
+        if( j<p->nLookahead ) continue;
+        for(j=0; j<p->nAction; j++){
+          if( p->aAction[j].lookahead==j+p->mnLookahead-i ) break;
+        }
+        if( j==p->nAction ){
+          break;  /* Fits in empty slots */
+        }
+      }
+    }
+  }
   /* Insert transaction set at index i. */
   for(j=0; j<p->nLookahead; j++){
     k = p->aLookahead[j].lookahead - p->mnLookahead + i;
@@ -3612,7 +3619,7 @@ int mhflag;     /* Output in makeheaders format if true */
   struct action *ap;
   struct rule *rp;
   struct acttab *pActtab;
-  int i, j, n;
+  int i, j, k, n;
   char *name;
   int mnTknOfst, mxTknOfst;
   int mnNtOfst, mxNtOfst;
@@ -3771,8 +3778,9 @@ int mhflag;     /* Output in makeheaders format if true */
   free(ax);
 
   /* Output the yy_action table */
-  fprintf(out,"static const YYACTIONTYPE yy_action[] = {\n"); lineno++;
   n = acttab_size(pActtab);
+  fprintf(out,"#define YY_ACTTAB_COUNT (%d)\n", n); lineno++;
+  fprintf(out,"static const YYACTIONTYPE yy_action[] = {\n"); lineno++;
   for(i=j=0; i<n; i++){
     int action = acttab_yyaction(pActtab, i);
     if( action<0 ) action = lemp->nstate + lemp->nrule + 2;
@@ -3807,7 +3815,9 @@ int mhflag;     /* Output in makeheaders format if true */
   fprintf(out, "#define YY_SHIFT_USE_DFLT (%d)\n", mnTknOfst-1); lineno++;
   n = lemp->nstate;
   while( n>0 && lemp->sorted[n-1]->iTknOfst==NO_OFFSET ) n--;
-  fprintf(out, "#define YY_SHIFT_MAX %d\n", n-1); lineno++;
+  fprintf(out, "#define YY_SHIFT_COUNT (%d)\n", n-1); lineno++;
+  fprintf(out, "#define YY_SHIFT_MIN   (%d)\n", mnTknOfst); lineno++;
+  fprintf(out, "#define YY_SHIFT_MAX   (%d)\n", mxTknOfst); lineno++;
   fprintf(out, "static const %s yy_shift_ofst[] = {\n", 
           minimum_size_type(mnTknOfst-1, mxTknOfst)); lineno++;
   for(i=j=0; i<n; i++){
@@ -3830,7 +3840,9 @@ int mhflag;     /* Output in makeheaders format if true */
   fprintf(out, "#define YY_REDUCE_USE_DFLT (%d)\n", mnNtOfst-1); lineno++;
   n = lemp->nstate;
   while( n>0 && lemp->sorted[n-1]->iNtOfst==NO_OFFSET ) n--;
-  fprintf(out, "#define YY_REDUCE_MAX %d\n", n-1); lineno++;
+  fprintf(out, "#define YY_REDUCE_COUNT (%d)\n", n-1); lineno++;
+  fprintf(out, "#define YY_REDUCE_MIN   (%d)\n", mnNtOfst); lineno++;
+  fprintf(out, "#define YY_REDUCE_MAX   (%d)\n", mxNtOfst); lineno++;
   fprintf(out, "static const %s yy_reduce_ofst[] = {\n", 
           minimum_size_type(mnNtOfst-1, mxNtOfst)); lineno++;
   for(i=j=0; i<n; i++){

tools/lemon/lempar.c

@@ -134,7 +134,6 @@ static const YYMINORTYPE yyzerominor = { 0 };
 **  yy_default[]       Default action for each state.
 */
 %%
-#define YY_SZ_ACTTAB (int)(sizeof(yy_action)/sizeof(yy_action[0]))
 
 /* The next table maps tokens into fallback tokens.  If a construct
 ** like the following:
@@ -394,12 +393,13 @@ static int yy_find_shift_action(
   int i;
   int stateno = pParser->yystack[pParser->yyidx].stateno;
  
-  if( stateno>YY_SHIFT_MAX || (i = yy_shift_ofst[stateno])==YY_SHIFT_USE_DFLT ){
+  if( stateno>YY_SHIFT_COUNT
+   || (i = yy_shift_ofst[stateno])==YY_SHIFT_USE_DFLT ){
     return yy_default[stateno];
   }
   assert( iLookAhead!=YYNOCODE );
   i += iLookAhead;
-  if( i<0 || i>=YY_SZ_ACTTAB || yy_lookahead[i]!=iLookAhead ){
+  if( i<0 || i>=YY_ACTTAB_COUNT || yy_lookahead[i]!=iLookAhead ){
     if( iLookAhead>0 ){
 #ifdef YYFALLBACK
       YYCODETYPE iFallback;            /* Fallback token */
@@ -417,7 +417,15 @@ static int yy_find_shift_action(
 #ifdef YYWILDCARD
       {
         int j = i - iLookAhead + YYWILDCARD;
-        if( j>=0 && j<YY_SZ_ACTTAB && yy_lookahead[j]==YYWILDCARD ){
+        if( 
+#if YY_SHIFT_MIN+YYWILDCARD<0
+          j>=0 &&
+#endif
+#if YY_SHIFT_MAX+YYWILDCARD>=YY_ACTTAB_COUNT
+          j<YY_ACTTAB_COUNT &&
+#endif
+          yy_lookahead[j]==YYWILDCARD
+        ){
 #ifndef NDEBUG
           if( yyTraceFILE ){
             fprintf(yyTraceFILE, "%sWILDCARD %s => %s\n",
@@ -449,22 +457,22 @@ static int yy_find_reduce_action(
 ){
   int i;
 #ifdef YYERRORSYMBOL
-  if( stateno>YY_REDUCE_MAX ){
+  if( stateno>YY_REDUCE_COUNT ){
 	return yy_default[stateno];
   }
 #else
-  assert( stateno<=YY_REDUCE_MAX );
+  assert( stateno<=YY_REDUCE_COUNT );
 #endif
   i = yy_reduce_ofst[stateno];
   assert( i!=YY_REDUCE_USE_DFLT );
   assert( iLookAhead!=YYNOCODE );
   i += iLookAhead;
 #ifdef YYERRORSYMBOL
-  if( i<0 || i>=YY_SZ_ACTTAB || yy_lookahead[i]!=iLookAhead ){
+  if( i<0 || i>=YY_ACTTAB_COUNT || yy_lookahead[i]!=iLookAhead ){
     return yy_default[stateno];
   }
 #else
-  assert( i>=0 && i<YY_SZ_ACTTAB );
+  assert( i>=0 && i<YY_ACTTAB_COUNT );
   assert( yy_lookahead[i]==iLookAhead );
 #endif
   return yy_action[i];