3 * Parser for C declarations.
4 * Copyright © 2011-2012, 2021, 2023 Nick Bowler
6 * This program is free software: you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation, either version 3 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
21 %name-prefix "cdecl__yy"
22 %parse-param {void *scanner}
23 %parse-param {struct cdecl **out}
24 %lex-param {yyscan_t scanner}
36 #include "cdecl-internal.h"
39 #define FAIL(msg) do { \
40 yyerror(&yylloc, NULL, NULL, msg); \
44 #define ALLOC(ptr, size) do { \
45 (ptr) = malloc(size); \
47 cdecl__errmsg(CDECL__ENOMEM); \
52 #define ALLOC_STRUCT(ptr, type, ...) do { \
53 ALLOC(ptr, sizeof (type)); \
54 *(ptr) = (type) { __VA_ARGS__ }; \
58 * With the postprocessing performed by fix-yytname.awk, all the symbol
59 * name strings can be used directly in error messages and there is no
60 * need for any string processing.
62 #define yytnamerr(a, b) cdecl__strlcpy(a, b, (a) ? INT_MAX : 0)
70 void cdecl__free(struct cdecl *);
71 int cdecl__yyparse(void *scanner, struct cdecl **out);
72 const char *cdecl__token_name(unsigned token);
80 struct cdecl_declspec *declspec;
81 struct cdecl_declarator *declarator;
86 static void yyerror(YYLTYPE *, yyscan_t, struct cdecl **, const char *);
87 static void free_decl(struct cdecl *);
89 static void free_declspec(struct cdecl_declspec *x)
91 struct cdecl_declspec *p;
100 static void free_declarator(struct cdecl_declarator *x)
102 struct cdecl_declarator *p;
108 case CDECL_DECL_NULL:
110 case CDECL_DECL_IDENT:
113 case CDECL_DECL_POINTER:
114 free_declspec(x->u.pointer.qualifiers);
116 case CDECL_DECL_ARRAY:
117 free(x->u.array.vla);
119 case CDECL_DECL_FUNCTION:
120 free_decl(x->u.function.parameters);
131 static void free_decl(struct cdecl *x)
138 /* The specifiers may be shared by an entire chain. */
139 if (!p || p->specifiers != x->specifiers)
140 free_declspec(x->specifiers);
142 free_declarator(x->declarators);
148 void cdecl__free(struct cdecl *decl)
154 * Join two declaration specifier lists into a single list, with "a" being the
155 * head of the new list.
157 * The list "a" is assumed to be nonempty.
159 static void join_specs(struct cdecl_declspec *a, struct cdecl_declspec *b)
167 * Alter an abstract declarator (type name) to declare an identifier instead,
168 * used by the English parser rules to reduce "identifier as type" sequences.
170 static struct cdecl *insert_identifier(struct cdecl *decl, char *ident)
172 struct cdecl_declarator *d = decl->declarators;
177 d->type = CDECL_DECL_IDENT;
184 %destructor { free($$); } <strval>
185 %destructor { free_declspec($$); } <declspec>
186 %destructor { free_declarator($$); } <declarator>
187 %destructor { free_decl($$); } <decl>
192 %token <strval> T_IDENT "identifier"
193 %token <uintval> T_UINT "integer constant"
195 %token T_SEMICOLON ";"
196 %token T_ASTERISK "*"
199 %token T_LBRACKET "["
200 %token T_RBRACKET "]"
202 %token T_ELLIPSIS "..."
204 %token <spectype> T_TYPEDEF "typedef"
205 %token <spectype> T_EXTERN "extern"
206 %token <spectype> T_STATIC "static"
207 %token <spectype> T_AUTO "auto"
208 %token <spectype> T_REGISTER "register"
210 %token <spectype> T_INLINE "inline"
212 %token <spectype> T_RESTRICT "restrict"
213 %token <spectype> T_VOLATILE "volatile"
214 %token <spectype> T_CONST "const"
216 %token <spectype> T_VOID "void"
217 %token <spectype> T_CHAR "char"
218 %token <spectype> T_SHORT "short"
219 %token <spectype> T_INT "int"
220 %token <spectype> T_LONG "long"
221 %token <spectype> T_FLOAT "float"
222 %token <spectype> T_DOUBLE "double"
223 %token <spectype> T_SIGNED "signed"
224 %token <spectype> T_UNSIGNED "unsigned"
225 %token <spectype> T_BOOL "_Bool"
226 %token <spectype> T_COMPLEX "_Complex"
227 %token <spectype> T_IMAGINARY "_Imaginary"
229 %token <spectype> T_STRUCT "struct"
230 %token <spectype> T_UNION "union"
231 %token <spectype> T_ENUM "enum"
237 %token T_DECLARE "declare"
238 %token T_POINTER "pointer"
239 %token T_FUNCTION "function"
240 %token T_RETURNING "returning"
241 %token T_ARRAY "array"
245 %token T_VLA "variable-length"
247 %type <strval> vla_ident
248 %type <uintval> array_length
249 %type <boolval> varargs
250 %type <spectype> declspec_simple qualifier_simple
251 %type <spectype> typespec_simple typespec_tagged
252 %type <declspec> declspec_notype declspec_noid typespec_noid typespec
253 %type <declspec> qualifier qualifiers
254 %type <declspec> declspecs declspecs_noid
255 %type <declarator> direct_declarator declarator pointer array parens postfix
256 %type <declarator> direct_declarator_ish declarator_ish parameter_type_list
257 %type <decl> declaration declarators declarator_wrap
258 %type <decl> parameter
260 %type <strval> english_vla
261 %type <declspec> storage_func_specs post_specs
262 %type <declspec> type_qual_spec type_qual_specs typedef_name_qual
263 %type <declarator> english_declarator english_array english_function
264 %type <declarator> english_parameter_list null_decl
265 %type <decl> english english_declaration
266 %type <decl> english_parameter
268 /* Precedence declaration to avoid conflict in english_parameter; see below. */
282 declaration: declspecs declarators semi {
288 * We support parsing declarations using arbitrary identifiers as type
289 * specifiers (a la C typedef). To avoid confusion with identifiers that
290 * may also be used as declarators, note the following:
292 * (a) Every valid C declaration must have at least one type specifier, and
293 * (b) Valid declarations with typedef names have exactly one type specifier.
295 * So the rule applied when parsing specifiers is: an identifier is a type
296 * specifier only if we have not yet seen any type specifiers whatsoever
297 * (within one declaration specifier list).
299 * Treating identifiers as type specifiers by default can lead to strange and
300 * unexpected parses; libcdecl applies a simplification step to the resulting
301 * parse tree afterwards.
303 declspecs: declspec_notype declspecs {
306 } | typespec declspecs_noid {
311 declspecs_noid: { $$ = NULL; } | declspec_noid declspecs_noid {
316 qualifiers: { $$ = NULL; } | qualifiers qualifier {
321 declarators: declarator_wrap | declarator_wrap T_COMMA declarators {
326 declarator_wrap: declarator {
327 ALLOC_STRUCT($$, struct cdecl, .declarators = $1);
330 declspec_simple: T_AUTO
337 typespec_simple: T_VOID
350 typespec_tagged: T_STRUCT | T_UNION | T_ENUM | { $$ = CDECL_TYPE_IDENT; }
352 qualifier_simple: T_CONST
356 declspec_notype: qualifier | declspec_simple {
357 ALLOC_STRUCT($$, struct cdecl_declspec, .type = $1);
360 typespec_noid: typespec_simple {
361 ALLOC_STRUCT($$, struct cdecl_declspec, .type = $1);
364 qualifier: qualifier_simple {
365 ALLOC_STRUCT($$, struct cdecl_declspec, .type = $1);
368 typespec: typespec_noid | typespec_tagged T_IDENT {
369 ALLOC_STRUCT($$, struct cdecl_declspec,
374 declspec_noid: declspec_notype | typespec_noid
376 vla_ident: T_IDENT | T_ASTERISK {
377 ALLOC($$, sizeof "");
381 array: T_LBRACKET array_length T_RBRACKET {
382 ALLOC_STRUCT($$, struct cdecl_declarator,
383 .type = CDECL_DECL_ARRAY,
384 .u.array.length = $2);
385 } | T_LBRACKET vla_ident T_RBRACKET {
386 ALLOC_STRUCT($$, struct cdecl_declarator,
387 .type = CDECL_DECL_ARRAY,
391 parameter: declspecs declarator {
392 ALLOC_STRUCT($$, struct cdecl,
397 varargs: { $$ = false; } | T_COMMA T_ELLIPSIS { $$ = true; }
399 parameter_type_list: parameter varargs {
400 ALLOC_STRUCT($$, struct cdecl_declarator,
401 .type = CDECL_DECL_FUNCTION,
402 .u.function.parameters = $1,
403 .u.function.variadic = $2);
404 } | parameter T_COMMA parameter_type_list {
406 $1->next = $$->u.function.parameters;
407 $$->u.function.parameters = $1;
410 parens: T_LPAREN parameter_type_list T_RPAREN {
412 } | T_LPAREN declarator_ish T_RPAREN {
413 ALLOC_STRUCT($$, struct cdecl_declarator,
414 .type = CDECL_DECL_FUNCTION);
415 ALLOC_STRUCT($$->u.function.parameters, struct cdecl,
419 pointer: T_ASTERISK qualifiers direct_declarator {
420 ALLOC_STRUCT($$, struct cdecl_declarator,
421 .type = CDECL_DECL_POINTER,
422 .u.pointer.qualifiers = $2,
424 } | T_ASTERISK qualifiers pointer {
425 ALLOC_STRUCT($$, struct cdecl_declarator,
426 .type = CDECL_DECL_POINTER,
427 .u.pointer.qualifiers = $2,
431 declarator: direct_declarator | pointer
432 declarator_ish: direct_declarator_ish | pointer
433 postfix: array | parens
435 direct_declarator_ish: {
436 ALLOC_STRUCT($$, struct cdecl_declarator,
437 .type = CDECL_DECL_NULL);
438 } | direct_declarator_ish postfix {
444 ALLOC_STRUCT($$, struct cdecl_declarator,
445 .type = CDECL_DECL_NULL);
447 ALLOC_STRUCT($$, struct cdecl_declarator,
448 .type = CDECL_DECL_IDENT,
450 } | direct_declarator postfix {
455 english: T_DECLARE T_IDENT T_AS english_declaration {
456 $$ = insert_identifier($4, $2);
457 } | T_TYPE english_declaration {
462 * We use a precedence declaration to prefer shifting an identifier
463 * over reducing this empty rule; see below.
465 storage_func_specs: %prec T_TYPE { $$ = NULL; }
466 storage_func_specs: declspec_simple storage_func_specs {
467 ALLOC_STRUCT($$, struct cdecl_declspec,
472 type_qual_spec: typespec_noid | qualifier
474 type_qual_specs: { $$ = NULL; } | type_qual_spec type_qual_specs {
480 * The "qualifiers" nonterminal needs to be used here to avoid shift/reduce
481 * conflicts with pointer declarators. So we end up needing to stitch
482 * together three different specifiers lists.
484 post_specs: qualifiers typespec type_qual_specs {
490 english_declaration: storage_func_specs english_declarator post_specs {
492 ALLOC_STRUCT($$, struct cdecl,
497 english_declarator: {
498 ALLOC_STRUCT($$, struct cdecl_declarator,
499 .type = CDECL_DECL_NULL);
500 } | english_declarator qualifiers T_POINTER T_TO {
501 ALLOC_STRUCT($$, struct cdecl_declarator,
502 .type = CDECL_DECL_POINTER,
504 .u.pointer.qualifiers = $2);
505 } | english_declarator english_array {
508 } | english_declarator english_function {
513 english_function: T_FUNCTION T_RETURNING {
514 ALLOC_STRUCT($$, struct cdecl_declarator,
515 .type = CDECL_DECL_FUNCTION,
516 .u.function.parameters = NULL);
517 } | T_FUNCTION T_LPAREN english_parameter_list T_RPAREN T_RETURNING {
521 english_parameter_list: english_parameter varargs {
522 ALLOC_STRUCT($$, struct cdecl_declarator,
523 .type = CDECL_DECL_FUNCTION,
524 .u.function.parameters = $1,
525 .u.function.variadic = $2);
526 } | english_parameter T_COMMA english_parameter_list {
528 $1->next = $$->u.function.parameters;
529 $$->u.function.parameters = $1;
532 typedef_name_qual: T_IDENT qualifiers {
533 ALLOC_STRUCT($$, struct cdecl_declspec,
534 .type = CDECL_TYPE_IDENT,
540 ALLOC_STRUCT($$, struct cdecl_declarator,
541 .type = CDECL_DECL_NULL);
545 * There is a shift/reduce conflict here when an identifier appears as the
546 * first token. The conflict is between shifting T_IDENT, or reducing the
547 * empty production for storage_func_specs (cf. english_declaration).
549 * - In either case, if we reduce, we won't match T_IDENT T_AS since the
550 * stack now has the extra storage_func_specs nonterminal symbol.
551 * - And if we shift, we won't match english_declaration since it is
552 * too late to add storage_func_specs to the stack.
554 * The only valid input affected by the conflict is a simple type names,
555 * possibly followed by qualifiers. So the conflict is adequately resolved
556 * by shifting, so long as we have a special-case reduction to handle this.
558 english_parameter: english_declaration | typedef_name_qual null_decl {
559 ALLOC_STRUCT($$, struct cdecl,
562 } | T_IDENT T_AS english_declaration {
563 $$ = insert_identifier($3, $1);
566 english_array: T_VLA T_ARRAY english_vla T_OF {
567 ALLOC_STRUCT($$, struct cdecl_declarator,
568 .type = CDECL_DECL_ARRAY,
570 } | T_ARRAY array_length T_OF {
571 ALLOC_STRUCT($$, struct cdecl_declarator,
572 .type = CDECL_DECL_ARRAY,
573 .u.array.length = $2);
576 array_length: { $$ = 0; }
577 array_length: T_UINT {
579 FAIL(_("array length must be positive"));
582 english_vla: T_IDENT | {
583 ALLOC($$, sizeof "");
590 * Expose the token string table to the rest of the library, in order to
591 * produce strings that match parser keywords.
593 * In order for this to work properly, the Bison output must be postprocessed
594 * by fix-yytname.awk to remove pointless quotation marks from the keyword
597 const char *cdecl__token_name(unsigned token)
599 return yytname[YYTRANSLATE(token)];
603 yyerror(YYLTYPE *loc, yyscan_t scanner, struct cdecl **out, const char *err)
605 if (strstr(err, yytname[YYTRANSLATE(T_LEX_ERROR)]))
608 cdecl__err(CDECL_ENOPARSE, "%s", err);