On Tue, 25 Jul 2006, Joel E. Denny wrote: > On Wed, 12 Jul 2006, Joel E. Denny wrote: > > > I went ahead. As far as I can tell, all the skeletons now (after my > > uncommitted patch below) consistently pop EOF one time upon a successful > > parse. > > I'd like to commit this patch. I'll do so in a few days if there are no > objections.
> The full patch is here: > > http://lists.gnu.org/archive/html/help-bison/2006-07/msg00023.html I committed the following. Joel Index: ChangeLog =================================================================== RCS file: /sources/bison/bison/ChangeLog,v retrieving revision 1.1538 diff -p -u -r1.1538 ChangeLog --- ChangeLog 25 Jul 2006 06:45:05 -0000 1.1538 +++ ChangeLog 29 Jul 2006 04:10:32 -0000 @@ -1,3 +1,32 @@ +2006-07-29 Joel E. Denny <[EMAIL PROTECTED]> + + Clean up handling of %destructor for the end token (token 0). + Discussed starting at + <http://lists.gnu.org/archive/html/bison-patches/2006-07/msg00019.html> + and + <http://lists.gnu.org/archive/html/help-bison/2006-07/msg00013.html>. + + Make the skeletons consistent in how they pop the end token and invoke + its %destructor. + * data/glr.c (yyrecoverSyntaxError, yyparse): Don't pop the start + state, which has token number 0, since this would invoke the + %destructor for the end token. + * data/lalr1.cc (yy::parser::parse): Don't check for the final state + until after shifting the end token, or else it won't be popped. + * data/yacc.c (yyparse): Likewise. + + * data/glr.c (yyparse): Clear the lookahead after shifting it even when + it's the end token. Upon termination, destroy an unshifted lookahead + even when it's the end token. + * data/lalr1.cc (yy::parser::parse): Likewise. + * data/yacc.c (yyparse): Likewise. + + * src/reader.c (packgram): Don't check rule 0. This suppresses unused + value warnings for the end token when the user gives the end token a + %destructor. + + * tests/actions.at (Printers and Destructors): Test all the above. + 2006-07-24 Paul Eggert <[EMAIL PROTECTED]> Update to latest gnulib and gettext versions. Index: data/glr.c =================================================================== RCS file: /sources/bison/bison/data/glr.c,v retrieving revision 1.185 diff -p -u -r1.185 glr.c --- data/glr.c 9 Jul 2006 20:36:33 -0000 1.185 +++ data/glr.c 29 Jul 2006 04:10:33 -0000 @@ -2261,7 +2261,8 @@ yyrecoverSyntaxError (yyGLRStack* yystac } } ]b4_locations_if([[ yystackp->yyerror_range[1].yystate.yyloc = yys->yyloc;]])[ - yydestroyGLRState ("Error: popping", yys]b4_user_args[); + if (yys->yypred != NULL) + yydestroyGLRState ("Error: popping", yys]b4_user_args[); yystackp->yytops.yystates[0] = yys->yypred; yystackp->yynextFree -= 1; yystackp->yyspaceLeft += 1; @@ -2373,8 +2374,7 @@ m4_popdef([b4_at_dollar])])dnl if (yyisShiftAction (yyaction)) { YY_SYMBOL_PRINT ("Shifting", yytoken, &yylval, &yylloc); - if (yychar != YYEOF) - yychar = YYEMPTY; + yychar = YYEMPTY; yyposn += 1; yyglrShift (&yystack, 0, yyaction, yyposn, &yylval, &yylloc); if (0 < yystack.yyerrState) @@ -2490,7 +2490,7 @@ m4_popdef([b4_at_dollar])])dnl goto yyreturn; yyreturn: - if (yychar != YYEOF && yychar != YYEMPTY) + if (yychar != YYEMPTY) yydestruct ("Cleanup: discarding lookahead", YYTRANSLATE (yychar), &yylval]b4_locations_if([, &yylloc])[]b4_user_args[); @@ -2512,7 +2512,8 @@ m4_popdef([b4_at_dollar])])dnl { yyGLRState *yys = yystates[yyk]; ]b4_locations_if([[ yystack.yyerror_range[1].yystate.yyloc = yys->yyloc;]] -)[ yydestroyGLRState ("Cleanup: popping", yys]b4_user_args[); +)[ if (yys->yypred != NULL) + yydestroyGLRState ("Cleanup: popping", yys]b4_user_args[); yystates[yyk] = yys->yypred; yystack.yynextFree -= 1; yystack.yyspaceLeft += 1; Index: data/lalr1.cc =================================================================== RCS file: /sources/bison/bison/data/lalr1.cc,v retrieving revision 1.138 diff -p -u -r1.138 lalr1.cc --- data/lalr1.cc 12 Jul 2006 18:01:19 -0000 1.138 +++ data/lalr1.cc 29 Jul 2006 04:10:33 -0000 @@ -567,6 +567,11 @@ m4_popdef([b4_at_dollar])])dnl yynewstate: yystate_stack_.push (yystate); YYCDEBUG << "Entering state " << yystate << std::endl; + + /* Accept? */ + if (yystate == yyfinal_) + goto yyacceptlab; + goto yybackup; /* Backup. */ @@ -616,16 +621,11 @@ m4_ifdef([b4_lex_param], [, ]b4_lex_para goto yyreduce; } - /* Accept? */ - if (yyn == yyfinal_) - goto yyacceptlab; - /* Shift the lookahead token. */ YY_SYMBOL_PRINT ("Shifting", yytoken, &yylval, &yylloc); - /* Discard the token being shifted unless it is eof. */ - if (yychar != yyeof_) - yychar = yyempty_; + /* Discard the token being shifted. */ + yychar = yyempty_; yysemantic_stack_.push (yylval); yylocation_stack_.push (yylloc); @@ -780,9 +780,6 @@ b4_error_verbose_if([, yytoken])[)); YY_STACK_PRINT (); } - if (yyn == yyfinal_) - goto yyacceptlab; - yyerror_range[1] = yylloc; // Using YYLLOC is tempting, but would change the location of // the lookahead. YYLOC is available though. @@ -808,7 +805,7 @@ b4_error_verbose_if([, yytoken])[)); goto yyreturn; yyreturn: - if (yychar != yyeof_ && yychar != yyempty_) + if (yychar != yyempty_) yydestruct_ ("Cleanup: discarding lookahead", yytoken, &yylval, &yylloc); /* Do not reclaim the symbols of the rule which action triggered Index: data/yacc.c =================================================================== RCS file: /sources/bison/bison/data/yacc.c,v retrieving revision 1.150 diff -p -u -r1.150 yacc.c --- data/yacc.c 9 Jul 2006 20:36:33 -0000 1.150 +++ data/yacc.c 29 Jul 2006 04:10:34 -0000 @@ -1164,6 +1164,9 @@ m4_ifdef([b4_at_dollar_used], [[ yylsp[ YYDPRINTF ((stderr, "Entering state %d\n", yystate)); + if (yystate == YYFINAL) + YYACCEPT; + goto yybackup; /*-----------. @@ -1213,9 +1216,6 @@ yybackup: goto yyreduce; } - if (yyn == YYFINAL) - YYACCEPT; - /* Count tokens shifted since error; after three, turn off error status. */ if (yyerrstatus) @@ -1224,9 +1224,8 @@ yybackup: /* Shift the lookahead token. */ YY_SYMBOL_PRINT ("Shifting", yytoken, &yylval, &yylloc); - /* Discard the shifted token unless it is eof. */ - if (yychar != YYEOF) - yychar = YYEMPTY; + /* Discard the shifted token. */ + yychar = YYEMPTY; yystate = yyn; *++yyvsp = yylval; @@ -1418,9 +1417,6 @@ yyerrlab1: YY_STACK_PRINT (yyss, yyssp); } - if (yyn == YYFINAL) - YYACCEPT; - *++yyvsp = yylval; ]b4_locations_if([[ yyerror_range[1] = yylloc; @@ -1461,7 +1457,7 @@ yyexhaustedlab: #endif yyreturn: - if (yychar != YYEOF && yychar != YYEMPTY) + if (yychar != YYEMPTY) yydestruct ("Cleanup: discarding lookahead", yytoken, &yylval]b4_locations_if([, &yylloc])[]b4_user_args[); /* Do not reclaim the symbols of the rule which action triggered Index: src/reader.c =================================================================== RCS file: /sources/bison/bison/src/reader.c,v retrieving revision 1.265 diff -p -u -r1.265 reader.c --- src/reader.c 9 Jul 2006 20:36:33 -0000 1.265 +++ src/reader.c 29 Jul 2006 04:10:34 -0000 @@ -488,7 +488,11 @@ packgram (void) rule. Thus, the midrule actions have already been scanned in order to set `used' flags for this rule's rhs, so grammar_rule_check will work properly. */ - grammar_rule_check (p); + /* Don't check the generated rule 0. It has no action, so some rhs + symbols may appear unused, but the parsing algorithm ensures that + %destructor's are invoked appropriately. */ + if (p != grammar) + grammar_rule_check (p); for (p = p->next; p && p->sym; p = p->next) { Index: tests/actions.at =================================================================== RCS file: /sources/bison/bison/tests/actions.at,v retrieving revision 1.60 diff -p -u -r1.60 actions.at --- tests/actions.at 23 Jun 2006 20:17:28 -0000 1.60 +++ tests/actions.at 29 Jul 2006 04:10:34 -0000 @@ -197,8 +197,9 @@ AT_LALR1_CC_IF([typedef yy::location YYL ]AT_LALR1_CC_IF([], [static void yyerror (const char *msg);]) [} -]m4_ifval([$6], [%type <ival> '(' 'x' 'y' ')' ';' thing line input])[ +]m4_ifval([$6], [%type <ival> '(' 'x' 'y' ')' ';' thing line input END])[ +/* FIXME: This %printer isn't actually tested. */ %printer { ]AT_LALR1_CC_IF([debug_stream () << $$;], @@ -226,6 +227,11 @@ AT_LALR1_CC_IF([typedef yy::location YYL { printf ("Freeing token 'y' ([EMAIL PROTECTED])\n", $$, RANGE (@$)); } 'y' +%token END 0 +%destructor + { printf ("Freeing token END ([EMAIL PROTECTED])\n", $$, RANGE (@$)); } + END + %% /* This grammar is made to exercise error recovery. @@ -241,7 +247,7 @@ input: printf ("input ([EMAIL PROTECTED]): /* Nothing */\n", $$, RANGE (@$)); } | line input /* Right recursive to load the stack so that popping at - EOF can be exercised. */ + END can be exercised. */ { $$ = 2; printf ("input ([EMAIL PROTECTED]): line ([EMAIL PROTECTED]) input ([EMAIL PROTECTED])\n", @@ -308,7 +314,7 @@ yylex (]AT_LEX_FORMALS[) if (source[c]) printf ("sending: '%c'", source[c]); else - printf ("sending: EOF"); + printf ("sending: END"); printf (" ([EMAIL PROTECTED])\n", c, RANGE (]AT_LOC[)); return source[c]; } @@ -372,9 +378,10 @@ sending: 'x' ([EMAIL PROTECTED]) thing ([EMAIL PROTECTED]): 'x' ([EMAIL PROTECTED]) sending: ')' ([EMAIL PROTECTED]) line ([EMAIL PROTECTED]): '(' ([EMAIL PROTECTED]) thing ([EMAIL PROTECTED]) ')' ([EMAIL PROTECTED]) -sending: EOF ([EMAIL PROTECTED]) +sending: END ([EMAIL PROTECTED]) input ([EMAIL PROTECTED]): /* Nothing */ input ([EMAIL PROTECTED]): line ([EMAIL PROTECTED]) input ([EMAIL PROTECTED]) +Freeing token END ([EMAIL PROTECTED]) Freeing nterm input ([EMAIL PROTECTED]) Successful parse. ]]) @@ -391,9 +398,10 @@ sending: 'y' ([EMAIL PROTECTED]) Freeing token 'y' ([EMAIL PROTECTED]) sending: ')' ([EMAIL PROTECTED]) line ([EMAIL PROTECTED]): '(' ([EMAIL PROTECTED]) error (@10-19) ')' ([EMAIL PROTECTED]) -sending: EOF ([EMAIL PROTECTED]) +sending: END ([EMAIL PROTECTED]) input ([EMAIL PROTECTED]): /* Nothing */ input ([EMAIL PROTECTED]): line ([EMAIL PROTECTED]) input ([EMAIL PROTECTED]) +Freeing token END ([EMAIL PROTECTED]) Freeing nterm input ([EMAIL PROTECTED]) Successful parse. ]]) @@ -445,12 +453,45 @@ input ([EMAIL PROTECTED]): /* Nothing */ input ([EMAIL PROTECTED]): line ([EMAIL PROTECTED]) input ([EMAIL PROTECTED]) input ([EMAIL PROTECTED]): line ([EMAIL PROTECTED]) input ([EMAIL PROTECTED]) input ([EMAIL PROTECTED]): line ([EMAIL PROTECTED]) input ([EMAIL PROTECTED]) -130-139: syntax error, unexpected 'y', expecting $end +130-139: syntax error, unexpected 'y', expecting END Freeing nterm input ([EMAIL PROTECTED]) Freeing token 'y' ([EMAIL PROTECTED]) Parsing FAILED. ]]) + +# Syntax error caught by the parser where lookahead = END +# -------------------------------------------------------- +# Load the stack and provoke an error that cannot be caught by the +# grammar, to check that the stack is cleared. And make sure the +# lookahead is freed. +# +# '(', 'x', ')', +# '(', 'x', ')', +# 'x' +AT_PARSER_CHECK([./input '(x)(x)x'], 1, +[[sending: '(' ([EMAIL PROTECTED]) +sending: 'x' ([EMAIL PROTECTED]) +thing ([EMAIL PROTECTED]): 'x' ([EMAIL PROTECTED]) +sending: ')' ([EMAIL PROTECTED]) +line ([EMAIL PROTECTED]): '(' ([EMAIL PROTECTED]) thing ([EMAIL PROTECTED]) ')' ([EMAIL PROTECTED]) +sending: '(' ([EMAIL PROTECTED]) +sending: 'x' ([EMAIL PROTECTED]) +thing ([EMAIL PROTECTED]): 'x' ([EMAIL PROTECTED]) +sending: ')' ([EMAIL PROTECTED]) +line ([EMAIL PROTECTED]): '(' ([EMAIL PROTECTED]) thing ([EMAIL PROTECTED]) ')' ([EMAIL PROTECTED]) +sending: 'x' ([EMAIL PROTECTED]) +thing ([EMAIL PROTECTED]): 'x' ([EMAIL PROTECTED]) +sending: END ([EMAIL PROTECTED]) +70-79: syntax error, unexpected END, expecting 'x' +Freeing nterm thing ([EMAIL PROTECTED]) +Freeing nterm line ([EMAIL PROTECTED]) +Freeing nterm line ([EMAIL PROTECTED]) +Freeing token END ([EMAIL PROTECTED]) +Parsing FAILED. +]]) + + # Check destruction upon stack overflow # ------------------------------------- # Upon stack overflow, all symbols on the stack should be destroyed. _______________________________________________ help-bison@gnu.org http://lists.gnu.org/mailman/listinfo/help-bison