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Clean up handling of %destructor for the end token (token 0).

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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.
This commit is contained in:
Joel E. Denny
2006-07-29 04:11:33 +00:00
parent 62a9592d3d
commit 868d2d9638
6 changed files with 101 additions and 33 deletions
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53
tests/actions.at
View File

@@ -197,8 +197,9 @@ AT_LALR1_CC_IF([typedef yy::location YYLTYPE;
]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 () << $$;],
@@ -226,6 +227,11 @@ AT_LALR1_CC_IF([typedef yy::location YYLTYPE;
{ printf ("Freeing token 'y' (%d@%d-%d)\n", $$, RANGE (@$)); }
'y'
%token END 0
%destructor
{ printf ("Freeing token END (%d@%d-%d)\n", $$, RANGE (@$)); }
END
%%
/*
This grammar is made to exercise error recovery.
@@ -241,7 +247,7 @@ input:
printf ("input (%d@%d-%d): /* Nothing */\n", $$, 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",
@@ -308,7 +314,7 @@ yylex (]AT_LEX_FORMALS[)
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];
}
@@ -372,9 +378,10 @@ 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: 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.
]])
@@ -391,9 +398,10 @@ sending: 'y' (1@10-19)
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.
]])
@@ -445,12 +453,45 @@ input (0@129-129): /* Nothing */
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.