Florian Krohm florian@edamail.fishkill.ibm.com
Frank Heckenbach frank@g-n-u.de
Frans Englich frans.englich@telia.com
+Gabriel Rassoul gabriel.rassoul@epita.fr
Georg Sauthoff gsauthof@TechFak.Uni-Bielefeld.DE
George Neuner gneuner2@comcast.net
Gilles Espinasse g.esp@free.fr
| rhses.1 ";"
;
+%token PERCENT_EMPTY "%empty";
rhs:
/* Nothing. */
{ grammar_current_rule_begin (current_lhs_symbol, current_lhs_location,
{ grammar_current_rule_action_append ($2, @2, $3, false); }
| rhs "%?{...}"
{ grammar_current_rule_action_append ($2, @2, NULL, true); }
+| rhs "%empty"
+ { grammar_current_rule_empty_set (@2); }
| rhs "%prec" symbol
{ grammar_current_rule_prec_set ($3, @3); }
| rhs "%dprec" INT
}
}
+ /* Check that %empty => empty rule. */
+ if (r->percent_empty_loc.start.file
+ && r->next && r->next->content.sym)
+ complain (&r->percent_empty_loc, complaint,
+ _("%%empty on non-empty rule"));
+
/* See comments in grammar_current_rule_prec_set for how POSIX
mandates this complaint. It's only for identifiers, so skip
it for char literals and strings, which are always tokens. */
current_rule->ruleprec = precsym;
}
+/* Set %empty for the current rule. */
+
+void
+grammar_current_rule_empty_set (location loc)
+{
+ if (current_rule->percent_empty_loc.start.file)
+ complain (&loc, complaint, _("only one %s allowed per rule"), "%empty");
+ else
+ current_rule->percent_empty_loc = loc;
+}
+
/* Attach dynamic precedence DPREC to the current rule. */
void
named_ref *lhs_named_ref);
void grammar_current_rule_end (location loc);
void grammar_midrule_action (void);
+/* Apply %empty to the current rule. */
+void grammar_current_rule_empty_set (location loc);
void grammar_current_rule_prec_set (symbol *precsym, location loc);
void grammar_current_rule_dprec_set (int dprec, location loc);
void grammar_current_rule_merge_set (uniqstr name, location loc);
"%defines" return PERCENT_DEFINES;
"%destructor" return PERCENT_DESTRUCTOR;
"%dprec" return PERCENT_DPREC;
+ "%empty" return PERCENT_EMPTY;
"%error-verbose" return PERCENT_ERROR_VERBOSE;
"%expect" return PERCENT_EXPECT;
"%expect-rr" return PERCENT_EXPECT_RR;
/* Members used for LHS only. */
res->ruleprec = NULL;
+ res->percent_empty_loc = empty_location;
code_props_none_init (&res->action_props);
res->dprec = 0;
res->merger = 0;
* each RHS are also stored here. */
code_props action_props;
+ /* The location of the first %empty for this rule, or \a
+ empty_location. */
+ location percent_empty_loc;
+
int dprec;
int merger;
location merger_declaration_location;
AT_CLEANUP
+## ------------------------ ##
+## Invalid uses of %empty. ##
+## ------------------------ ##
+
+AT_SETUP([Invalid uses of %empty])
+
+AT_DATA_GRAMMAR([[one.y]],
+[[%%
+exp:
+ %empty %empty {}
+;
+]])
+
+AT_BISON_CHECK([-fcaret one.y], [1], [],
+[[one.y:11.10-15: error: only one %empty allowed per rule
+ %empty %empty {}
+ ^^^^^^
+]])
+
+AT_DATA_GRAMMAR([[two.y]],
+[[%%
+exp:
+ 'a' %empty {}
+| %empty 'a' {}
+| %empty {} {}
+;
+]])
+
+AT_BISON_CHECK([-fcaret two.y], [1], [],
+[[two.y:11.7-12: error: %empty on non-empty rule
+ 'a' %empty {}
+ ^^^^^^
+two.y:12.3-8: error: %empty on non-empty rule
+ | %empty 'a' {}
+ ^^^^^^
+two.y:13.3-8: error: %empty on non-empty rule
+ | %empty {} {}
+ ^^^^^^
+]])
+
+AT_CLEANUP
+
+## ---------------------- ##
+## Valid uses of %empty. ##
+## ---------------------- ##
+
+AT_SETUP([Valid uses of %empty])
+
+AT_BISON_OPTION_PUSHDEFS
+AT_DATA_GRAMMAR([[input.y]],
+[[
+%debug
+%code
+{
+]AT_YYERROR_DECLARE[
+]AT_YYLEX_DECLARE[
+}
+%%
+exp: %empty {}
+%%
+]AT_YYERROR_DEFINE[
+]AT_YYLEX_DEFINE[
+]AT_MAIN_DEFINE[
+]])
+
+AT_FULL_COMPILE([input])
+AT_PARSER_CHECK([./input])
+AT_BISON_OPTION_POPDEFS
+AT_CLEANUP
## ------------------ ##
## Initial location. ##