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| author | François Pottier <francois.pottier@inria.fr> | 2015-10-07 10:49:42 +0200 |
|---|---|---|
| committer | François Pottier <francois.pottier@inria.fr> | 2015-10-07 10:49:42 +0200 |
| commit | 09527e66514edcfa20a0341acd75c1fe6fd77363 (patch) | |
| tree | c0983f011758c1d8cbe3ad748a3f157a89bf6d6d | |
| parent | c1937e330a3ca6c19ef648e2dcfe4871fc3c2219 (diff) | |
| download | compcert-09527e66514edcfa20a0341acd75c1fe6fd77363.tar.gz compcert-09527e66514edcfa20a0341acd75c1fe6fd77363.zip | |
Introduced optional(X, Y), which means X? Y, and used it in array declarators and FOR loops.
This leads to fewer automaton states, and potentially better error messages.
| -rw-r--r-- | cparser/pre_parser.mly | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/cparser/pre_parser.mly b/cparser/pre_parser.mly index 497851bf..62a57618 100644 --- a/cparser/pre_parser.mly +++ b/cparser/pre_parser.mly @@ -97,6 +97,14 @@ option(X): | x = X { Some x } +(* [optional(X, Y)] is equivalent to [X? Y]. However, by inlining + the two possibilies -- either [X Y] or just [Y] -- we are able + to give more meaningful syntax error messages. [optional(X, Y)] + itself is usually NOT inlined, as that would cause a useless + explosion of cases. *) +optional(X, Y): + ioption(X) Y {} + %inline fst(X): | x = X { fst x } @@ -537,7 +545,7 @@ direct_declarator: | i = general_identifier { set_id_type i VarId; (i, None) } | LPAREN x = declarator RPAREN -| x = direct_declarator LBRACK type_qualifier_list? assignment_expression? RBRACK +| x = direct_declarator LBRACK type_qualifier_list? optional(assignment_expression, RBRACK) { x } | x = direct_declarator LPAREN open_context parameter_type_list? restore_fun = save_contexts_stk @@ -583,7 +591,7 @@ abstract_declarator: direct_abstract_declarator: | LPAREN abstract_declarator RPAREN -| option(direct_abstract_declarator) LBRACK type_qualifier_list? assignment_expression? RBRACK +| option(direct_abstract_declarator) LBRACK type_qualifier_list? optional(assignment_expression, RBRACK) | ioption(direct_abstract_declarator) LPAREN in_context(parameter_type_list?) RPAREN {} @@ -764,8 +772,8 @@ iteration_statement(openc,last_statement): | WHILE openc LPAREN expression RPAREN last_statement | DO open_context statement_finish_close WHILE openc LPAREN expression RPAREN close_context SEMICOLON -| FOR openc LPAREN expression? SEMICOLON expression? SEMICOLON expression? RPAREN last_statement -| FOR openc LPAREN declaration expression? SEMICOLON expression? RPAREN last_statement +| FOR openc LPAREN optional(expression, SEMICOLON) optional(expression, SEMICOLON) optional(expression, RPAREN) last_statement +| FOR openc LPAREN declaration optional(expression, SEMICOLON) optional(expression, RPAREN) last_statement {} asm_attributes: |