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Bison grammar: parse higher ranked constraints in where clauses

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This commit is contained in:
Brian Leibig 2015-03-01 13:59:12 -08:00
parent f1fe1b5d4f
commit 481b21cf19
1 changed files with 12 additions and 2 deletions
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14
src/grammar/parser-lalr.y
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@ -152,6 +152,12 @@ extern char *yytext;
%precedence MOD_SEP %precedence MOD_SEP
%precedence RARROW ':' %precedence RARROW ':'
// In where clauses, "for" should have greater precedence when used as
// a higher ranked constraint than when used as the beginning of a
// for_in_type (which is a ty)
%precedence FORTYPE
%precedence FOR
// Binops & unops, and their precedences // Binops & unops, and their precedences
%precedence BOX %precedence BOX
%precedence BOXPLACE %precedence BOXPLACE
@ -777,10 +783,14 @@ where_predicates
; ;
where_predicate where_predicate
: lifetime ':' bounds { $$ = mk_node("WherePredicate", 2, $1, $3); } : maybe_for_lifetimes lifetime ':' bounds { $$ = mk_node("WherePredicate", 3, $1, $2, $4); }
| ty ':' ty_param_bounds { $$ = mk_node("WherePredicate", 2, $1, $3); } | maybe_for_lifetimes ty ':' ty_param_bounds { $$ = mk_node("WherePredicate", 3, $1, $2, $4); }
; ;
maybe_for_lifetimes
: FOR '<' lifetimes '>' { $$ = mk_none(); }
| %prec FORTYPE %empty { $$ = mk_none(); }
ty_params ty_params
: ty_param { $$ = mk_node("TyParams", 1, $1); } : ty_param { $$ = mk_node("TyParams", 1, $1); }
| ty_params ',' ty_param { $$ = ext_node($1, 1, $3); } | ty_params ',' ty_param { $$ = ext_node($1, 1, $3); }