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tokens: properly define the YYEOF token kind

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Currently EOF is handled in an adhoc way, with a #define YYEOF 0 in
the implementation file.  As a result, the user has to define her own
EOF token if she wants to use it, which is a pity.

Give the $end token a visible kind name, YYEOF.  Except that in C,
where enums are not scoped, we would have collisions between all the
definitions of YYEOFs in the header files, so in C, make it
<api.PREFIX>EOF.

* data/skeletons/c.m4 (YYEOF): Override its name to avoid collisions.
Unless the user already gave it a different name.
* data/skeletons/glr.c (YYEOF): Remove.
Use ]b4_symbol(0, [id])[ instead.
Add support for "pre_epilogue", for glr.cc.
* data/skeletons/glr.cc: Remove dead code (never emitted #undefs).
* data/skeletons/yacc.c
* src/parse-gram.c
* src/reader.c
* src/symtab.c
* tests/actions.at
* tests/input.at
This commit is contained in:
Akim Demaille
2020-04-10 18:31:07 +02:00
parent 95421df67b
commit e50de09886
11 changed files with 70 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files

9
src/parse-gram.c
View File

@@ -900,7 +900,6 @@ enum { YYENOMEM = -2 };
#define yyerrok (yyerrstatus = 0)
#define yyclearin (yychar = YYEMPTY)
#define YYEMPTY (-2)
#define YYEOF 0
#define YYACCEPT goto yyacceptlab
#define YYABORT goto yyabortlab
@@ -1950,9 +1949,9 @@ yybackup:
yychar = yylex (&yylval, &yylloc);
}
if (yychar <= YYEOF)
if (yychar <= GRAM_EOF)
{
yychar = YYEOF;
yychar = GRAM_EOF;
yytoken = YYSYMBOL_YYEOF;
YYDPRINTF ((stderr, "Now at end of input.\n"));
}
@@ -2643,10 +2642,10 @@ yyerrlab:
/* If just tried and failed to reuse lookahead token after an
error, discard it. */
if (yychar <= YYEOF)
if (yychar <= GRAM_EOF)
{
/* Return failure if at end of input. */
if (yychar == YYEOF)
if (yychar == GRAM_EOF)
YYABORT;
}
else

7
src/reader.c
View File

@@ -778,11 +778,16 @@ check_and_convert_grammar (void)
/* If the user did not define her ENDTOKEN, do it now. */
if (!endtoken)
{
endtoken = symbol_get ("$end", empty_loc);
endtoken = symbol_get ("YYEOF", empty_loc);
endtoken->content->class = token_sym;
endtoken->content->number = 0;
/* Value specified by POSIX. */
endtoken->content->user_token_number = 0;
{
symbol *alias = symbol_get ("$end", empty_loc);
symbol_class_set (alias, token_sym, empty_loc, false);
symbol_make_alias (endtoken, alias, empty_loc);
}
}
/* Report any undefined symbols and consider them nonterminals. */

5
src/symtab.c
View File

@@ -70,9 +70,12 @@ bool tag_seen = false;
static bool
symbol_is_user_defined (symbol *sym)
{
const bool eof_is_user_defined
= !endtoken->alias || STRNEQ (endtoken->alias->tag, "$end");
return sym->tag[0] != '$'
&& (eof_is_user_defined || (sym != endtoken && sym->alias != errtoken))
&& sym != errtoken && sym->alias != errtoken
&& sym != undeftoken && sym->alias != undeftoken;
&& sym != undeftoken && sym->alias != undeftoken;
}