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multistart: also give access to yynerrs

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This is something that has always bothered me: with pure parsers (and
they all should be) the user does not have an (easy) access to yynerrs
at the end of the parse.  In the case of error recovery, that's the
only direct means to know if there were errors.  The usual approach
being having the user maintain a counter incremented each time yyerror
is called.

So here, also capture yynerrs in the return value of the start-symbol
parsing functions.

* data/skeletons/yacc.c (yy_parse_impl_t): New.
(yy_parse_impl): Use it.
(b4_accept): Fill it.
* examples/c/lexcalc/parse.y, examples/c/lexcalc/scan.l: No longer
pass nerrs as lex- and parse-param, just use the resulting yynerrs.
bistromathic and reccalc both demonstrate %param.
This commit is contained in:
Akim Demaille
2020-08-03 19:02:15 +02:00
parent f4d33ff4b4
commit d441a34791
4 changed files with 39 additions and 24 deletions
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26
data/skeletons/yacc.c
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@@ -123,7 +123,7 @@ m4_ifset([b4_parse_param], [b4_args(b4_parse_param), ])])
# before, using the slot of SYMBOL-NUM.
m4_define([b4_accept],
[m4_ifval([$1],
[b4_symbol_value((*yyvalue), [$1]) = b4_rhs_value(2, 1, [$1]); ])YYACCEPT])
[b4_symbol_value(yyimpl->yyvalue, [$1]) = b4_rhs_value(2, 1, [$1]); ]) YYACCEPT])
# b4_lhs_value(SYMBOL-NUM, [TYPE])
@@ -176,6 +176,7 @@ typedef struct
{]b4_symbol_if([$1], [has_type], [[
]_b4_symbol($1, type)[ yyvalue;]])[
int yystatus;
int yynerrs;
} ]b4_prefix[parse_]_b4_symbol($1, id)[_t;
// Parse one ]_b4_symbol($1, tag)[.
@@ -200,10 +201,11 @@ m4_define([_b4_define_sub_yyparse],
yyparse_]_b4_symbol($1, id)[ (]m4_ifset([b4_parse_param], [b4_formals(b4_parse_param)], [void])[)
{
]b4_prefix[parse_]_b4_symbol($1, id)[_t yyres;
YYSTYPE yyvalue;
yyres.yystatus = yy_parse_impl (]b4_symbol($2, id)[, &yyvalue]m4_ifset([b4_parse_param],
yy_parse_impl_t yyimpl;
yyres.yystatus = yy_parse_impl (]b4_symbol($2, id)[, &yyimpl]m4_ifset([b4_parse_param],
[[, ]b4_args(b4_parse_param)])[);]b4_symbol_if([$1], [has_type], [[
yyres.yyvalue = yyvalue.]b4_symbol($1, slot)[;]])[
yyres.yyvalue = yyimpl.yyvalue.]b4_symbol($1, slot)[;]])[
yyres.yynerrs = yyimpl.yynerrs;
return yyres;
}
]])
@@ -1595,9 +1597,16 @@ yypush_parse (yypstate *yyps]b4_pure_if([[,
`----------*/
]m4_ifdef([b4_start_symbols],
[[
[[// Extract data from the parser.
typedef struct
{
YYSTYPE yyvalue;
int yynerrs;
} yy_parse_impl_t;
// Run a full parse, using YYCHAR as switching token.
static int
yy_parse_impl (int yychar, YYSTYPE *yyvalue]m4_ifset([b4_parse_param], [, b4_formals(b4_parse_param)])[);
yy_parse_impl (int yychar, yy_parse_impl_t *yyimpl]m4_ifset([b4_parse_param], [, b4_formals(b4_parse_param)])[);
]m4_map([_b4_define_sub_yyparse], m4_defn([b4_start_symbols]))[
@@ -1609,7 +1618,7 @@ yyparse (]m4_ifset([b4_parse_param], [b4_formals(b4_parse_param)], [void])[)
}
static int
yy_parse_impl (int yychar, YYSTYPE *yyvalue]m4_ifset([b4_parse_param], [, b4_formals(b4_parse_param)])[)]],
yy_parse_impl (int yychar, yy_parse_impl_t *yyimpl]m4_ifset([b4_parse_param], [, b4_formals(b4_parse_param)])[)]],
[[int
yyparse (]m4_ifset([b4_parse_param], [b4_formals(b4_parse_param)], [void])[)]])])[
{]b4_pure_if([b4_declare_scanner_communication_variables
@@ -2172,7 +2181,8 @@ yypushreturn:]], [[
YYSTACK_FREE (yyes);]])])[
]b4_parse_error_bmatch([detailed\|verbose],
[[ if (yymsg != yymsgbuf)
YYSTACK_FREE (yymsg);]])[
YYSTACK_FREE (yymsg);]])[]m4_ifdef([b4_start_symbols], [[
yyimpl->yynerrs = yynerrs;]])[
return yyresult;
}
]b4_push_if([b4_parse_state_variable_macros([b4_macro_undef])])[