yacc.c: add custom error message generation

When parse.error is custom, let users define a yyreport_syntax_error
function, and use it.

* data/skeletons/bison.m4 (b4_error_verbose_if): Accept 'custom'.
* data/skeletons/yacc.c: Implement it.
* examples/c/calc/calc.y: Experiment with it.
This commit is contained in:
Akim Demaille
2020-01-03 09:50:09 +01:00
parent 5b883180e6
commit cda1934606
3 changed files with 40 additions and 3 deletions

View File

@@ -1136,7 +1136,11 @@ yysyntax_error_arguments (const yyparse_context_t *yyctx,
}
]])[
]m4_case(b4_percent_define_get([[parse.error]]), [verbose],
]m4_case(b4_percent_define_get([[parse.error]]),
[custom],
[[static int
yyreport_syntax_error (const yyparse_context_t *yyctx);]],
[verbose],
[[# ifndef yystrlen
# if defined __GLIBC__ && defined _STRING_H
# define yystrlen(S) (YY_CAST (YYPTRDIFF_T, strlen (S)))
@@ -1786,6 +1790,15 @@ yyerrlab:
{
++yynerrs;
]m4_case(b4_percent_define_get([[parse.error]]),
[custom],
[[ {
yyparse_context_t yyctx
= {yyssp, yytoken]b4_lac_if([[, yyesa, &yyes, &yyes_capacity]])[};]b4_lac_if([[
if (yychar != YYEMPTY)
YY_LAC_ESTABLISH;]])[
if (yyreport_syntax_error (]b4_yyerror_args[&yyctx) == 2)
goto yyexhaustedlab;
}]],
[simple],
[[ yyerror (]b4_yyerror_args[YY_("syntax error"));]],
[verbose],