During deterministic GLR operation, user actions should be able to

influence the parse by changing yychar.  To make this easier to fix and
to make glr.c easier to evolve in general, don't maintain yytoken in
parallel with yychar; just compute yytoken when needed.
* tests/glr-regression.at (Incorrect lookahead during deterministic
GLR): Check that setting yychar in a user action has the intended
effect.
* data/glr.c (yyGLRStack): Remove yytokenp member.
(yyclearin): Don't set *yytokenp.
(yyprocessOneStack, yyreportSyntaxError, yyrecoverSyntaxError): Examine
yychar rather than *yytokenp to determine the current lookahead.
Compute yytoken locally when needed.
(yyparse): Likewise.  Remove the local yytoken that yytokenp used to
point to.

* doc/bison.texinfo (Bison Options): Remove stray sentence fragment
after `--report' documentation.

diff --git a/ChangeLog b/ChangeLog
index dbd051c2f341c20c2294335121714e93dce2e9a9..0721a932ea4c12be377cac5f4d3468b5b7aafc10 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,23 @@
+2006-01-30  Joel E. Denny  <jdenny@ces.clemson.edu>
+
+       During deterministic GLR operation, user actions should be able to
+       influence the parse by changing yychar.  To make this easier to fix and
+       to make glr.c easier to evolve in general, don't maintain yytoken in
+       parallel with yychar; just compute yytoken when needed.
+       * tests/glr-regression.at (Incorrect lookahead during deterministic
+       GLR): Check that setting yychar in a user action has the intended
+       effect.
+       * data/glr.c (yyGLRStack): Remove yytokenp member.
+       (yyclearin): Don't set *yytokenp.
+       (yyprocessOneStack, yyreportSyntaxError, yyrecoverSyntaxError): Examine
+       yychar rather than *yytokenp to determine the current lookahead.
+       Compute yytoken locally when needed.
+       (yyparse): Likewise.  Remove the local yytoken that yytokenp used to
+       point to.
+
+       * doc/bison.texinfo (Bison Options): Remove stray sentence fragment
+       after `--report' documentation.
+
 2006-01-30  Paul Eggert  <eggert@cs.ucla.edu>
 
        * src/parse-gram.y (grammar_declaration): Location of printer

diff --git a/data/glr.c b/data/glr.c
index e35cf78b63dca427b90bdca3aaf4ae01d2b51597..3430f1bb81e227b1f4abce01d333775a8c802443 100644 (file)
--- a/data/glr.c
+++ b/data/glr.c
@@ -803,7 +803,6 @@ struct yyGLRStack {
   YYSTYPE yyval;
   YYLTYPE yyloc;
 ])[
-  yySymbol* yytokenp;
   YYJMP_BUF yyexception_buffer;
   yyGLRStackItem* yyitems;
   yyGLRStackItem* yynextFree;
@@ -910,7 +909,7 @@ yyuserAction (yyRuleNum yyn, int yyrhslen, yyGLRStackItem* yyvsp,
 # undef YYRECOVERING
 # define YYRECOVERING (yystackp->yyerrState != 0)
 # undef yyclearin
-# define yyclearin (yychar = *(yystackp->yytokenp) = YYEMPTY)
+# define yyclearin (yychar = YYEMPTY)
 # undef YYFILL
 # define YYFILL(N) yyfill (yyvsp, &yylow, N, yynormal)
 # undef YYBACKUP
@@ -1929,7 +1928,6 @@ yyprocessOneStack (yyGLRStack* yystackp, size_t yyk,
   int yyaction;
   const short int* yyconflicts;
   yyRuleNum yyrule;
-  yySymbol* const yytokenp = yystackp->yytokenp;
 
   while (yystackp->yytops.yystates[yyk] != NULL)
     {
@@ -1953,15 +1951,18 @@ yyprocessOneStack (yyGLRStack* yystackp, size_t yyk,
        }
       else
        {
+         yySymbol yytoken;
          yystackp->yytops.yylookaheadNeeds[yyk] = yytrue;
-         if (*yytokenp == YYEMPTY)
+         if (yychar == YYEMPTY)
            {
              YYDPRINTF ((stderr, "Reading a token: "));
              yychar = YYLEX;
-             *yytokenp = YYTRANSLATE (yychar);
-             YY_SYMBOL_PRINT ("Next token is", *yytokenp, &yylval, &yylloc);
+             yytoken = YYTRANSLATE (yychar);
+             YY_SYMBOL_PRINT ("Next token is", yytoken, &yylval, &yylloc);
            }
-         yygetLRActions (yystate, *yytokenp, &yyaction, &yyconflicts);
+         else
+           yytoken = YYTRANSLATE (yychar);
+         yygetLRActions (yystate, yytoken, &yyaction, &yyconflicts);
 
          while (*yyconflicts != 0)
            {
@@ -1999,12 +2000,12 @@ yyreportSyntaxError (yyGLRStack* yystackp]b4_user_formals[)
   if (yystackp->yyerrState == 0)
     {
 #if YYERROR_VERBOSE
-      yySymbol* const yytokenp = yystackp->yytokenp;
       int yyn;
       yyn = yypact[yystackp->yytops.yystates[0]->yylrState];
       if (YYPACT_NINF < yyn && yyn < YYLAST)
        {
-         size_t yysize0 = yytnamerr (NULL, yytokenName (*yytokenp));
+         yySymbol yytoken = YYTRANSLATE (yychar);
+         size_t yysize0 = yytnamerr (NULL, yytokenName (yytoken));
          size_t yysize = yysize0;
          size_t yysize1;
          yybool yysize_overflow = yyfalse;
@@ -2032,7 +2033,7 @@ yyreportSyntaxError (yyGLRStack* yystackp]b4_user_formals[)
          int yyxend = yychecklim < YYNTOKENS ? yychecklim : YYNTOKENS;
          int yycount = 1;
 
-         yyarg[0] = yytokenName (*yytokenp);
+         yyarg[0] = yytokenName (yytoken);
          yyfmt = yystpcpy (yyformat, yyunexpected);
 
          for (yyx = yyxbegin; yyx < yyxend; ++yyx)
@@ -2100,7 +2101,6 @@ yyreportSyntaxError (yyGLRStack* yystackp]b4_user_formals[)
 /*ARGSUSED*/ static void
 yyrecoverSyntaxError (yyGLRStack* yystackp]b4_user_formals[)
 {
-  yySymbol* const yytokenp = yystackp->yytokenp;
   size_t yyk;
   int yyj;
 
@@ -2109,9 +2109,10 @@ yyrecoverSyntaxError (yyGLRStack* yystackp]b4_user_formals[)
        reductions.  Skip tokens until we can proceed.  */
     while (YYID (yytrue))
       {
-       if (*yytokenp == YYEOF)
+       yySymbol yytoken;
+       if (yychar == YYEOF)
          yyFail (yystackp][]b4_lpure_args[, NULL);
-       if (*yytokenp != YYEMPTY)
+       if (yychar != YYEMPTY)
          {]b4_location_if([[
            /* We throw away the lookahead, but the error range
               of the shifted error token must take it into account.  */
@@ -2120,18 +2121,19 @@ yyrecoverSyntaxError (yyGLRStack* yystackp]b4_user_formals[)
            yyerror_range[1].yystate.yyloc = yys->yyloc;
            yyerror_range[2].yystate.yyloc = yylloc;
            YYLLOC_DEFAULT ((yys->yyloc), yyerror_range, 2);]])[
+           yytoken = YYTRANSLATE (yychar);
            yydestruct ("Error: discarding",
-                       *yytokenp, &yylval]b4_location_if([, &yylloc])[]b4_user_args[);
+                       yytoken, &yylval]b4_location_if([, &yylloc])[]b4_user_args[);
          }
        YYDPRINTF ((stderr, "Reading a token: "));
        yychar = YYLEX;
-       *yytokenp = YYTRANSLATE (yychar);
-       YY_SYMBOL_PRINT ("Next token is", *yytokenp, &yylval, &yylloc);
+       yytoken = YYTRANSLATE (yychar);
+       YY_SYMBOL_PRINT ("Next token is", yytoken, &yylval, &yylloc);
        yyj = yypact[yystackp->yytops.yystates[0]->yylrState];
        if (yyis_pact_ninf (yyj))
          return;
-       yyj += *yytokenp;
-       if (yyj < 0 || YYLAST < yyj || yycheck[yyj] != *yytokenp)
+       yyj += yytoken;
+       if (yyj < 0 || YYLAST < yyj || yycheck[yyj] != yytoken)
          {
            if (yydefact[yystackp->yytops.yystates[0]->yylrState] != 0)
              return;
@@ -2209,7 +2211,6 @@ yyrecoverSyntaxError (yyGLRStack* yystackp]b4_user_formals[)
 ]b4_c_ansi_function_def([yyparse], [int], b4_parse_param)[
 {
   int yyresult;
-  yySymbol yytoken;
   yyGLRStack yystack;
   yyGLRStack* const yystackp = &yystack;
   size_t yyposn;
@@ -2217,7 +2218,6 @@ yyrecoverSyntaxError (yyGLRStack* yystackp]b4_user_formals[)
   YYDPRINTF ((stderr, "Starting parse\n"));
 
   yychar = YYEMPTY;
-  yytoken = YYEMPTY;
   yylval = yyval_default;
 ]b4_location_if([
 #if YYLTYPE_IS_TRIVIAL
@@ -2244,7 +2244,6 @@ b4_syncline([@oline@], [@ofile@])])dnl
     case 2: goto yyexhaustedlab;
     default: goto yybuglab;
     }
-  yystack.yytokenp = &yytoken;
   yyglrShift (&yystack, 0, 0, 0, &yylval, &yylloc);
   yyposn = 0;
 
@@ -2277,24 +2276,24 @@ b4_syncline([@oline@], [@ofile@])])dnl
            }
          else
            {
-             if (yytoken == YYEMPTY)
+             yySymbol yytoken;
+             if (yychar == YYEMPTY)
                {
                  YYDPRINTF ((stderr, "Reading a token: "));
                  yychar = YYLEX;
                  yytoken = YYTRANSLATE (yychar);
                  YY_SYMBOL_PRINT ("Next token is", yytoken, &yylval, &yylloc);
                }
+             else
+               yytoken = YYTRANSLATE (yychar);
              yygetLRActions (yystate, yytoken, &yyaction, &yyconflicts);
              if (*yyconflicts != 0)
                break;
              if (yyisShiftAction (yyaction))
                {
                  YY_SYMBOL_PRINT ("Shifting", yytoken, &yylval, &yylloc);
-                 if (yytoken != YYEOF)
-                   {
-                     yychar = YYEMPTY;
-                     yytoken = YYEMPTY;
-                   }
+                 if (yychar != YYEOF)
+                   yychar = YYEMPTY;
                  yyposn += 1;
                  yyglrShift (&yystack, 0, yyaction, yyposn, &yylval, &yylloc);
                  if (0 < yystack.yyerrState)
@@ -2346,12 +2345,11 @@ b4_syncline([@oline@], [@ofile@])])dnl
 
          /* If any yyglrShift call fails, it will fail after shifting.  Thus,
             a copy of yylval will already be on stack 0 in the event of a
-            failure in the following loop.  Thus, yytoken is set to YYEMPTY
+            failure in the following loop.  Thus, yychar is set to YYEMPTY
             before the loop to make sure the user destructor for yylval isn't
             called twice.  */
-         yytoken_to_shift = yytoken;
+         yytoken_to_shift = YYTRANSLATE (yychar);
          yychar = YYEMPTY;
-         yytoken = YYEMPTY;
          yyposn += 1;
          for (yys = 0; yys < yyn; yys += 1)
            {
@@ -2412,9 +2410,10 @@ b4_syncline([@oline@], [@ofile@])])dnl
   goto yyreturn;
 
  yyreturn:
-  if (yytoken != YYEOF && yytoken != YYEMPTY)
+  if (yychar != YYEOF && yychar != YYEMPTY)
     yydestruct ("Cleanup: discarding lookahead",
-               yytoken, &yylval]b4_location_if([, &yylloc])[]b4_user_args[);
+               YYTRANSLATE (yychar),
+               &yylval]b4_location_if([, &yylloc])[]b4_user_args[);
 
   /* If the stack is well-formed, pop the stack until it is empty,
      destroying its entries as we go.  But free the stack regardless

diff --git a/doc/bison.texinfo b/doc/bison.texinfo
index c0c56c0d8766134472e5c45a9b5a3b30ca64713c..c004a842a73125edb6f2b7b49775b5db3d76bc10 100644 (file)
--- a/doc/bison.texinfo
+++ b/doc/bison.texinfo
@@ -6889,8 +6889,6 @@ Implies @code{state} and augments the description of the automaton with
 the full set of items for each state, instead of its core only.
 @end table
 
-For instance, on the following grammar
-
 @item -v
 @itemx --verbose
 Pretend that @code{%verbose} was specified, i.e, write an extra output

diff --git a/src/parse-gram.c b/src/parse-gram.c
index d923bc4f446350c65545594ea1756207b15fdbce..2a28ff983d30faa3044b1016e8461abf65082057 100644 (file)
--- a/src/parse-gram.c
+++ b/src/parse-gram.c
@@ -1912,7 +1912,7 @@ yyreduce:
     {
       symbol_list *list;
       for (list = (yyvsp[(2) - (2)].list); list; list = list->next)
-       symbol_printer_set (list->sym, (yyvsp[(1) - (2)].chars), list->location);
+       symbol_printer_set (list->sym, (yyvsp[(1) - (2)].chars), (yylsp[(1) - (2)]));
       symbol_list_free ((yyvsp[(2) - (2)].list));
     }
     break;

diff --git a/src/parse-gram.h b/src/parse-gram.h
index cf303fd83d07b3a0b46a0066d137fd5215b25c72..2f6511093dcaceddd41ff8d75adddc5343ad775b 100644 (file)
--- a/src/parse-gram.h
+++ b/src/parse-gram.h
@@ -148,7 +148,7 @@ typedef union YYSTYPE
   uniqstr uniqstr;
 }
 /* Line 1536 of yacc.c.  */
-#line 152 "parse-gram.h"
+#line 152 "y.tab.h"
        YYSTYPE;
 # define yystype YYSTYPE /* obsolescent; will be withdrawn */
 # define YYSTYPE_IS_DECLARED 1

diff --git a/tests/glr-regression.at b/tests/glr-regression.at
index 536f5eb8a5784a72e1df7fb5cb43227a7397540e..8e6cd7808adf5e3030c54f441c609f496f749a4e 100644 (file)
--- a/tests/glr-regression.at
+++ b/tests/glr-regression.at
@@ -1016,7 +1016,8 @@ AT_CLEANUP
 
 ## ------------------------------------------------------------------------- ##
 ## Incorrect lookahead during deterministic GLR.  See                       ##
-## <http://lists.gnu.org/archive/html/help-bison/2005-07/msg00017.html>.     ##
+## <http://lists.gnu.org/archive/html/help-bison/2005-07/msg00017.html> and  ##
+## <http://lists.gnu.org/archive/html/bison-patches/2006-01/msg00060.html>.  ##
 ## ------------------------------------------------------------------------- ##
 
 AT_SETUP([Incorrect lookahead during deterministic GLR])
@@ -1027,7 +1028,8 @@ AT_DATA_GRAMMAR([glr-regr13.y],
      - Defaulted state with initial yychar: yychar == YYEMPTY.
      - Nondefaulted state: yychar != YYEMPTY.
      - Defaulted state after lookahead: yychar != YYEMPTY.
-     - Defaulted state after shift: yychar == YYEMPTY.  */
+     - Defaulted state after shift: yychar == YYEMPTY.
+     - User action changing the lookahead.  */
 
 %{
   #include <stdio.h>
@@ -1045,7 +1047,7 @@ AT_DATA_GRAMMAR([glr-regr13.y],
 %%
 
 start:
-  defstate_init defstate_shift 'b' {
+  defstate_init defstate_shift 'b' change_lookahead 'a' {
     USE ($3);
     print_look_ahead ("start <- defstate_init defstate_shift 'b'");
   }
@@ -1075,6 +1077,11 @@ nondefstate:
     print_look_ahead ("nondefstate <- 'b'");
   }
   ;
+change_lookahead:
+  {
+    yychar = 'a';
+  }
+  ;
 
 %%