Re: incorrect yychar for unambiguous GLR

[Joel E. Denny]

On Wed, 11 Jan 2006, Joel E. Denny wrote:

> On Wed, 11 Jan 2006, Paul Hilfinger wrote:
> 
> > > I agree about yylookaheadStatuses.  However, yylookaheadAvailable sounds 
> > > like it means yychar != YYEMPTY.  The polarity of yylookaheadUnused is 
> > > confusing, and it sounds like it might indicate whether the lookahead has 
> > > been shifted.  How about yylookaheadNeeds, which follows from my comments 
> > > above its declaration and maintains the plural?  I'm open to other 
> > > suggestions of course.
> > 
> > That one's fine.  
> 
> OK, I'll rename it.

I installed this.

Joel

2006-01-12  Joel E. Denny  <address@hidden>

        * data/glr.c (yyGLRStateSet): Rename yylookaheadStatuses to
        yylookaheadNeeds.  All uses updated.
        (yysplitStack): Rename local yynewLookaheadStatuses to
        yynewLookaheadNeeds.
        * data/glr-regression.at (Incorrect lookahead during nondeterministic
        GLR): In comments, change `lookahead status' to `lookahead need'.

Index: data/glr.c
===================================================================
RCS file: /sources/bison/bison/data/glr.c,v
retrieving revision 1.158
diff -p -u -r1.158 glr.c
--- data/glr.c  12 Jan 2006 00:16:35 -0000      1.158
+++ data/glr.c  12 Jan 2006 01:20:07 -0000
@@ -761,11 +761,11 @@ struct yyGLRState {
 
 struct yyGLRStateSet {
   yyGLRState** yystates;
-  /** During nondeterministic operation, yylookaheadStatuses tracks which
+  /** During nondeterministic operation, yylookaheadNeeds tracks which
    *  stacks have actually needed the current lookahead.  During deterministic
-   *  operation, yylookaheadStatuses[0] is not maintained since it would merely
+   *  operation, yylookaheadNeeds[0] is not maintained since it would merely
    *  duplicate yychar != YYEMPTY.  */
-  yybool* yylookaheadStatuses;
+  yybool* yylookaheadNeeds;
   size_t yysize, yycapacity;
 };
 
@@ -1113,7 +1113,7 @@ yyaddDeferredAction (yyGLRStack* yystack
     &yynewGLRStackItem (yystackp, yyfalse)->yyoption;
   yynewOption->yystate = rhs;
   yynewOption->yyrule = yyrule;
-  if (yystackp->yytops.yylookaheadStatuses[yyk])
+  if (yystackp->yytops.yylookaheadNeeds[yyk])
     {
       yynewOption->yyrawchar = yychar;
       yynewOption->yyval = yylval;
@@ -1139,9 +1139,9 @@ yyinitStateSet (yyGLRStateSet* yyset)
   if (! yyset->yystates)
     return yyfalse;
   yyset->yystates[0] = NULL;
-  yyset->yylookaheadStatuses =
-    (yybool*) YYMALLOC (16 * sizeof yyset->yylookaheadStatuses[0]);
-  if (! yyset->yylookaheadStatuses)
+  yyset->yylookaheadNeeds =
+    (yybool*) YYMALLOC (16 * sizeof yyset->yylookaheadNeeds[0]);
+  if (! yyset->yylookaheadNeeds)
     {
       YYFREE (yyset->yystates);
       return yyfalse;
@@ -1152,7 +1152,7 @@ yyinitStateSet (yyGLRStateSet* yyset)
 static void yyfreeStateSet (yyGLRStateSet* yyset)
 {
   YYFREE (yyset->yystates);
-  YYFREE (yyset->yylookaheadStatuses);
+  YYFREE (yyset->yylookaheadNeeds);
 }
 
 /** Initialize STACK to a single empty stack, with total maximum
@@ -1300,12 +1300,12 @@ yyremoveDeletes (yyGLRStack* yystackp)
        {
          yystackp->yytops.yystates[yyj] = yystackp->yytops.yystates[yyi];
          /* In the current implementation, it's unnecessary to copy
-            yystackp->yytops.yylookaheadStatuses[yyi] since, after
+            yystackp->yytops.yylookaheadNeeds[yyi] since, after
             yyremoveDeletes returns, the parser immediately either enters
             deterministic operation or shifts a token.  However, it doesn't
             hurt, and the code might evolve to need it.  */
-         yystackp->yytops.yylookaheadStatuses[yyj] =
-           yystackp->yytops.yylookaheadStatuses[yyi];
+         yystackp->yytops.yylookaheadNeeds[yyj] =
+           yystackp->yytops.yylookaheadNeeds[yyi];
          if (yyj != yyi)
            {
              YYDPRINTF ((stderr, "Rename stack %lu -> %lu.\n",
@@ -1533,7 +1533,7 @@ yysplitStack (yyGLRStack* yystackp, size
   if (yystackp->yytops.yysize >= yystackp->yytops.yycapacity)
     {
       yyGLRState** yynewStates;
-      yybool* yynewLookaheadStatuses;
+      yybool* yynewLookaheadNeeds;
 
       yynewStates = NULL;
       
@@ -1550,18 +1550,18 @@ yysplitStack (yyGLRStack* yystackp, size
        yyMemoryExhausted (yystackp);
       yystackp->yytops.yystates = yynewStates;
 
-      yynewLookaheadStatuses =
-       (yybool*) YYREALLOC (yystackp->yytops.yylookaheadStatuses,
+      yynewLookaheadNeeds =
+       (yybool*) YYREALLOC (yystackp->yytops.yylookaheadNeeds,
                             (yystackp->yytops.yycapacity
-                             * sizeof yynewLookaheadStatuses[0]));
-      if (yynewLookaheadStatuses == NULL)
+                             * sizeof yynewLookaheadNeeds[0]));
+      if (yynewLookaheadNeeds == NULL)
        yyMemoryExhausted (yystackp);
-      yystackp->yytops.yylookaheadStatuses = yynewLookaheadStatuses;
+      yystackp->yytops.yylookaheadNeeds = yynewLookaheadNeeds;
     }
   yystackp->yytops.yystates[yystackp->yytops.yysize]
     = yystackp->yytops.yystates[yyk];
-  yystackp->yytops.yylookaheadStatuses[yystackp->yytops.yysize]
-    = yystackp->yytops.yylookaheadStatuses[yyk];
+  yystackp->yytops.yylookaheadNeeds[yystackp->yytops.yysize]
+    = yystackp->yytops.yylookaheadNeeds[yyk];
   yystackp->yytops.yysize += 1;
   return yystackp->yytops.yysize-1;
 }
@@ -1953,7 +1953,7 @@ yyprocessOneStack (yyGLRStack* yystackp,
        }
       else
        {
-         yystackp->yytops.yylookaheadStatuses[yyk] = yytrue;
+         yystackp->yytops.yylookaheadNeeds[yyk] = yytrue;
          if (*yytokenp == YYEMPTY)
            {
              YYDPRINTF ((stderr, "Reading a token: "));
@@ -2318,7 +2318,7 @@ b4_syncline(address@hidden@], address@hidden@])])dnl
          size_t yyn = yystack.yytops.yysize;
 
          for (yys = 0; yys < yyn; yys += 1)
-           yystackp->yytops.yylookaheadStatuses[yys] = yychar != YYEMPTY;
+           yystackp->yytops.yylookaheadNeeds[yys] = yychar != YYEMPTY;
 
          /* yyprocessOneStack returns one of three things:
 
Index: tests/glr-regression.at
===================================================================
RCS file: /sources/bison/bison/tests/glr-regression.at,v
retrieving revision 1.26
diff -p -u -r1.26 glr-regression.at
--- tests/glr-regression.at     8 Jan 2006 23:16:51 -0000       1.26
+++ tests/glr-regression.at     12 Jan 2006 01:20:07 -0000
@@ -1151,17 +1151,17 @@ AT_SETUP([Incorrect lookahead during non
 AT_DATA_GRAMMAR([glr-regr14.y],
 [[
 /* Tests:
-     - Conflicting actions (split-off parse, which copies lookahead status,
+     - Conflicting actions (split-off parse, which copies lookahead need,
        which is necessarily yytrue) and nonconflicting actions (non-split-off
        parse) for nondefaulted state: yychar != YYEMPTY.
-     - Merged deferred actions (lookahead status and RHS from different stack
+     - Merged deferred actions (lookahead need and RHS from different stack
        than the target state) and nonmerged deferred actions (same stack).
      - Defaulted state after lookahead: yychar != YYEMPTY.
      - Defaulted state after shift: yychar == YYEMPTY.
-     - yychar != YYEMPTY but lookahead status is yyfalse (a previous stack has
+     - yychar != YYEMPTY but lookahead need is yyfalse (a previous stack has
        seen the lookahead but current stack has not).
      - Exceeding stack capacity (stack explosion), and thus reallocating
-       lookahead status array.
+       lookahead need array.
    Note that it does not seem possible to see the initial yychar value during
    nondeterministic operation since:
      - In order to preserve the initial yychar, only defaulted states may be
@@ -1193,8 +1193,7 @@ start:
   }
   ;
 
-/* When merging the 2 deferred actions, the lookahead statuses are
-   different.  */
+/* When merging the 2 deferred actions, the lookahead needs are different.  */
 merge:
   nonconflict1 'a' 'b' nonconflict2 %dprec 1 {
     USE ($2); USE ($3);
@@ -1232,7 +1231,7 @@ defstate_look:
   }
   ;
 
-/* yychar != YYEMPTY but lookahead status is yyfalse.  */
+/* yychar != YYEMPTY but lookahead need is yyfalse.  */
 defstate_shift:
   {
     print_look_ahead ("defstate_shift <- empty string");