+2006-07-29 Joel E. Denny <jdenny@ces.clemson.edu>
+
+ 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 <eggert@cs.ucla.edu>
Update to latest gnulib and gettext versions.
}
}
]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;
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)
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[);
{
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;
yynewstate:
yystate_stack_.push (yystate);
YYCDEBUG << "Entering state " << yystate << std::endl;
+
+ /* Accept? */
+ if (yystate == yyfinal_)
+ goto yyacceptlab;
+
goto yybackup;
/* Backup. */
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);
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.
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
YYDPRINTF ((stderr, "Entering state %d\n", yystate));
+ if (yystate == YYFINAL)
+ YYACCEPT;
+
goto yybackup;
/*-----------.
goto yyreduce;
}
- if (yyn == YYFINAL)
- YYACCEPT;
-
/* Count tokens shifted since error; after three, turn off error
status. */
if (yyerrstatus)
/* 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;
YY_STACK_PRINT (yyss, yyssp);
}
- if (yyn == YYFINAL)
- YYACCEPT;
-
*++yyvsp = yylval;
]b4_locations_if([[
yyerror_range[1] = yylloc;
#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
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)
{
]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 () << $$;],
{ printf ("Freeing token 'y' (%d@%d-%d)\n", $$, RANGE (@$)); }
'y'
+%token END 0
+%destructor
+ { printf ("Freeing token END (%d@%d-%d)\n", $$, RANGE (@$)); }
+ END
+
%%
/*
This grammar is made to exercise error recovery.
printf ("input (%d@%d-%d): /* Nothing */\n", $$, RANGE (@$));
}
| line input /* Right recursive to load the stack so that popping at
- EOF can be exercised. */
+ END can be exercised. */
{
$$ = 2;
printf ("input (%d@%d-%d): line (%d@%d-%d) input (%d@%d-%d)\n",
if (source[c])
printf ("sending: '%c'", source[c]);
else
- printf ("sending: EOF");
+ printf ("sending: END");
printf (" (%d@%d-%d)\n", c, RANGE (]AT_LOC[));
return source[c];
}
thing (1@10-19): 'x' (1@10-19)
sending: ')' (2@20-29)
line (0@0-29): '(' (0@0-9) thing (1@10-19) ')' (2@20-29)
-sending: EOF (3@30-39)
+sending: END (3@30-39)
input (0@29-29): /* Nothing */
input (2@0-29): line (0@0-29) input (0@29-29)
+Freeing token END (3@30-39)
Freeing nterm input (2@0-29)
Successful parse.
]])
Freeing token 'y' (1@10-19)
sending: ')' (2@20-29)
line (-1@0-29): '(' (0@0-9) error (@10-19) ')' (2@20-29)
-sending: EOF (3@30-39)
+sending: END (3@30-39)
input (0@29-29): /* Nothing */
input (2@0-29): line (-1@0-29) input (0@29-29)
+Freeing token END (3@30-39)
Freeing nterm input (2@0-29)
Successful parse.
]])
input (2@100-129): line (10@100-129) input (0@129-129)
input (2@70-129): line (7@70-99) input (2@100-129)
input (2@0-129): line (-1@0-69) input (2@70-129)
-130-139: syntax error, unexpected 'y', expecting $end
+130-139: syntax error, unexpected 'y', expecting END
Freeing nterm input (2@0-129)
Freeing token 'y' (13@130-139)
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: '(' (0@0-9)
+sending: 'x' (1@10-19)
+thing (1@10-19): 'x' (1@10-19)
+sending: ')' (2@20-29)
+line (0@0-29): '(' (0@0-9) thing (1@10-19) ')' (2@20-29)
+sending: '(' (3@30-39)
+sending: 'x' (4@40-49)
+thing (4@40-49): 'x' (4@40-49)
+sending: ')' (5@50-59)
+line (3@30-59): '(' (3@30-39) thing (4@40-49) ')' (5@50-59)
+sending: 'x' (6@60-69)
+thing (6@60-69): 'x' (6@60-69)
+sending: END (7@70-79)
+70-79: syntax error, unexpected END, expecting 'x'
+Freeing nterm thing (6@60-69)
+Freeing nterm line (3@30-59)
+Freeing nterm line (0@0-29)
+Freeing token END (7@70-79)
+Parsing FAILED.
+]])
+
+
# Check destruction upon stack overflow
# -------------------------------------
# Upon stack overflow, all symbols on the stack should be destroyed.
projects / bison.git / commitdiff
