%code top {
/*
* Parser for C declarations.
* Copyright © 2011-2012, 2021, 2023-2024 Nick Bowler
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see .
*/
}
%name-prefix "cdecl__yy"
%parse-param {void *scanner}
%parse-param {struct cdecl **out}
%lex-param {yyscan_t scanner}
%define api.pure
%error-verbose
%locations
%{
#include
#include
#include
#include "scan.h"
#include "cdecl-internal.h"
#include "errmsg.h"
/*
* Allocate a parse tree node via cdecl__alloc_item.
*
* - m1 specifies the item's union member to assign to ptr, which selects the
* type of node to allocate.
*
* - m2 specifies the "next" or "child" member, which is initialized to a null
* pointer. The cdecl__alloc_item function sets the declarator.child member
* to null; we explicitly copy this null pointer to the returned union member
* to avoid type punning. It is hoped that compilers will notice that these
* pointers are at the same offset therefore the assignment can be elided.
*
* The resulting pointer can be passed directly to free, as the union is the
* first member of the parse_item structure.
*
* Use the wrapper macros below instead of this one.
*/
#define ALLOC_ITEM(ptr, m1, m2) do { \
struct parse_item *item; \
if (!(item = cdecl__alloc_item(0))) \
YYERROR; \
item->u.m1.m2 = (void *)item->u.declarator.child; \
(ptr) = &item->u.m1; \
} while (0)
/* Wrappers for ALLOC_ITEM to allocate various kinds of parser structures. */
#define ALLOC_ITEM_DECLARATOR(ptr) ALLOC_ITEM(ptr, declarator, child)
#define ALLOC_ITEM_DECLSPEC(ptr) ALLOC_ITEM(ptr, declspec, next)
#define ALLOC_ITEM_DECL(ptr) ALLOC_ITEM(ptr, decl, next)
#define ALLOC_FUNCTION_(ptr, parameters_) do { \
ALLOC_ITEM_DECLARATOR(ptr); \
(ptr)->type = CDECL_DECL_FUNCTION; \
(ptr)->u.function.parameters = parameters_; \
} while (0)
#define ALLOC_FUNCTION(ptr, parameters_, variadic_) do { \
ALLOC_FUNCTION_(ptr, parameters_); \
(ptr)->u.function.variadic = variadic_; \
} while (0)
#define ALLOC_ARRAY(ptr, length_) do { \
ALLOC_ITEM_DECLARATOR(ptr); \
(ptr)->type = CDECL_DECL_ARRAY; \
(ptr)->u.array.vla = NULL; \
(ptr)->u.array.length = length_; \
} while (0)
#define ALLOC_POINTER(ptr, qualifiers_, child_) do { \
ALLOC_ITEM_DECLARATOR(ptr); \
(ptr)->child = child_; \
(ptr)->type = CDECL_DECL_POINTER; \
(ptr)->u.pointer.qualifiers = qualifiers_; \
} while (0)
#define ALLOC_DECLSPEC(ptr, type_) do { \
ALLOC_ITEM_DECLSPEC(ptr); \
(ptr)->type = type_; \
(ptr)->ident = NULL; \
} while (0)
#define ALLOC_DECL(ptr, specifiers_, declarators_) do { \
ALLOC_ITEM_DECL(ptr); \
(ptr)->specifiers = specifiers_; \
(ptr)->declarators = declarators_; \
} while (0)
/*
* With the postprocessing performed by fix-yytname.awk, all the symbol
* name strings can be used directly in error messages and there is no
* need for any string processing.
*/
#define yytnamerr(a, b) ( (a) ? cdecl__strlcpy(a, b, -1) : strlen(b) )
%}
%code requires {
#include
#include
#include "cdecl.h"
}
%code provides {
void cdecl__free(struct cdecl *);
int cdecl__yyparse(void *scanner, struct cdecl **out);
const char *cdecl__token_name(unsigned token);
}
%union {
cdecl_uintmax uintval;
unsigned spectype;
bool boolval;
struct cdecl_declspec *declspec;
struct cdecl_declarator *declarator;
struct cdecl *decl;
struct parse_item *item;
}
%{
static void yyerror(YYLTYPE *, yyscan_t, struct cdecl **, const char *);
static void free_decl(struct cdecl *);
static void free_declspec(struct cdecl_declspec *x)
{
struct cdecl_declspec *p;
while (x) {
p = x->next;
free(x);
x = p;
}
}
static void free_declarator(struct cdecl_declarator *x)
{
struct cdecl_declarator *p;
while (x) {
p = x->child;
switch (x->type) {
case CDECL_DECL_NULL:
x = NULL;
case CDECL_DECL_IDENT:
case CDECL_DECL_ARRAY:
break;
case CDECL_DECL_POINTER:
free_declspec(x->u.pointer.qualifiers);
break;
case CDECL_DECL_FUNCTION:
free_decl(x->u.function.parameters);
break;
default:
assert(0);
}
free(x);
x = p;
}
}
static void free_decl(struct cdecl *x)
{
struct cdecl *p;
while (x) {
p = x->next;
/* The specifiers may be shared by an entire chain. */
if (!p || p->specifiers != x->specifiers)
free_declspec(x->specifiers);
free_declarator(x->declarators);
free(x);
x = p;
}
}
void cdecl__free(struct cdecl *decl)
{
free_decl(decl);
}
/*
* Join two declaration specifier lists into a single list, with "a" being the
* head of the new list.
*
* The list "a" is assumed to be nonempty.
*/
static void join_specs(struct cdecl_declspec *a, struct cdecl_declspec *b)
{
while (a->next)
a = a->next;
a->next = b;
}
/*
* Join three specifier lists into a single list, and returns the head of
* the new list.
*
* The list "b" is assumed to be a singleton list.
*/
static struct cdecl_declspec *join_specs3(struct cdecl_declspec *a,
struct cdecl_declspec *b,
struct cdecl_declspec *c)
{
b->next = c;
join_specs(b, a);
return b;
}
/*
* Reverse the order of a "struct cdecl" list, and return the new first
* element of the list (i.e., the last element of the original list).
*/
static struct cdecl *reverse_decls(struct cdecl *decl)
{
struct cdecl *prev, *next;
for (prev = NULL; decl; decl = next) {
next = decl->next;
decl->next = prev;
prev = decl;
}
return prev;
}
/*
* Alter an abstract declarator (type name) to declare an identifier instead,
* used by the English parser rules to reduce "identifier as type" sequences.
*/
static struct cdecl *
insert_identifier(struct cdecl *decl, struct parse_item *ident)
{
struct cdecl_declarator *d, **p = &decl->declarators;
while ((d = *p)->child)
p = &d->child;
*p = &ident->u.declarator;
return decl;
}
static struct cdecl_declarator *nulldecl(void)
{
static const struct cdecl_declarator nulldecl = {0};
return (void *)&nulldecl;
}
#define NULLDECL (nulldecl())
%}
%destructor { free($$); } -
%destructor { free_declspec($$); }
%destructor { free_declarator($$); }
%destructor { free_decl($$); }
/* Magic tokens */
%token T_LEX_ERROR "@@@"
%token
- T_IDENT "identifier"
%token T_UINT "integer constant"
%token T_SEMICOLON ";"
%token T_ASTERISK "*"
%token T_LPAREN "("
%token T_RPAREN ")"
%token T_LBRACKET "["
%token T_RBRACKET "]"
%token T_COMMA ","
%token T_ELLIPSIS "..."
%token T_TYPEDEF "typedef"
%token T_EXTERN "extern"
%token T_STATIC "static"
%token T_AUTO "auto"
%token T_REGISTER "register"
%token T_INLINE "inline"
%token T_RESTRICT "restrict"
%token T_VOLATILE "volatile"
%token T_CONST "const"
%token T_VOID "void"
%token T_CHAR "char"
%token T_SHORT "short"
%token T_INT "int"
%token T_LONG "long"
%token T_FLOAT "float"
%token T_DOUBLE "double"
%token T_SIGNED "signed"
%token T_UNSIGNED "unsigned"
%token T_BOOL "_Bool"
%token T_COMPLEX "_Complex"
%token T_IMAGINARY "_Imaginary"
%token T_STRUCT "struct"
%token T_UNION "union"
%token T_ENUM "enum"
/*
* English keywords.
*/
%token T_TYPE "type"
%token T_DECLARE "declare"
%token T_POINTER "pointer"
%token T_FUNCTION "function"
%token T_RETURNING "returning"
%token T_ARRAY "array"
%token T_TO "to"
%token T_OF "of"
%token T_AS "as"
%token T_VLA "variable-length"
%type
- vla_ident
%type array_length
%type varargs
%type declspec_simple qualifier_simple
%type typespec_simple typespec_tagged
%type declspec_notype declspec_noid typespec_noid typespec
%type qualifier qualifiers
%type declspecs declspecs_notype declspecs_noid
%type direct_declarator declarator pointer array parens postfix
%type direct_declarator_ish declarator_ish parameter_type_list
%type cdecl declaration declarators declarator_wrap parameter
%type
- english_vla
%type storage_func_specs post_specs
%type type_qual_spec type_qual_specs typedef_name_qual
%type english_declarator english_array english_function
%type english_parameter_list null_decl
%type english english_declaration english_parameter
/* Precedence declaration to avoid conflict in english_parameter; see below. */
%right T_TYPE
%right T_IDENT
%%
input: cdecl { *out = $1; }
cdecl: english | declaration
semi: | T_SEMICOLON
declaration: declspecs declarators semi {
$$ = reverse_decls($2);
$$->specifiers = $1;
};
/*
* We support parsing declarations using arbitrary identifiers as type
* specifiers (a la C typedef). To avoid confusion with identifiers that
* may also be used as declarators, note the following:
*
* (a) Every valid C declaration must have at least one type specifier, and
* (b) Valid declarations with typedef names have exactly one type specifier.
*
* So the rule applied when parsing specifiers is: an identifier is a type
* specifier only if we have not yet seen any type specifiers whatsoever
* (within one declaration specifier list).
*
* Treating identifiers as type specifiers by default can lead to strange and
* unexpected parses; libcdecl applies a simplification step to the resulting
* parse tree afterwards.
*/
declspecs: declspecs_notype typespec declspecs_noid {
$$ = join_specs3($1, $2, $3);
}
declspecs_notype: { $$ = NULL; } | declspecs_notype declspec_notype {
$$ = $2;
$$->next = $1;
}
declspecs_noid: { $$ = NULL; } | declspecs_noid declspec_noid {
$$ = $2;
$$->next = $1;
}
qualifiers: { $$ = NULL; } | qualifiers qualifier {
$$ = $2;
$$->next = $1;
}
declarators: declarator_wrap | declarators T_COMMA declarator_wrap {
$$ = $3;
$$->next = $1;
}
declarator_wrap: declarator {
ALLOC_DECL($$, NULL, $1);
}
declspec_simple: T_AUTO
| T_TYPEDEF
| T_EXTERN
| T_STATIC
| T_REGISTER
| T_INLINE
typespec_simple: T_VOID
| T_CHAR
| T_SHORT
| T_INT
| T_LONG
| T_FLOAT
| T_DOUBLE
| T_SIGNED
| T_UNSIGNED
| T_BOOL
| T_COMPLEX
| T_IMAGINARY
typespec_tagged: T_STRUCT | T_UNION | T_ENUM | { $$ = CDECL_TYPE_IDENT; }
qualifier_simple: T_CONST
| T_RESTRICT
| T_VOLATILE
declspec_notype: qualifier | declspec_simple { ALLOC_DECLSPEC($$, $1); }
typespec_noid: typespec_simple { ALLOC_DECLSPEC($$, $1); }
qualifier: qualifier_simple { ALLOC_DECLSPEC($$, $1); }
typespec: typespec_noid | typespec_tagged T_IDENT {
/* Compiler should be able to elide this assignment. */
$2->u.declspec.ident = $2->u.declarator.u.ident;
$$ = &$2->u.declspec;
$$->type = $1;
}
declspec_noid: declspec_notype | typespec_noid
vla_ident: T_IDENT | T_ASTERISK {
if (!($$ = cdecl__alloc_item(1)))
YYERROR;
*$$->s = 0;
}
array: T_LBRACKET array_length T_RBRACKET {
ALLOC_ARRAY($$, $2);
} | T_LBRACKET vla_ident T_RBRACKET {
$$ = &$2->u.declarator;
$$->type = CDECL_DECL_ARRAY;
$$->u.array.vla = $$->u.ident;
$$->u.array.length = 0;
}
parameter: declspecs declarator {
ALLOC_DECL($$, $1, $2);
}
varargs: { $$ = false; } | T_COMMA T_ELLIPSIS { $$ = true; }
parameter_type_list: parameter {
ALLOC_FUNCTION_($$, $1);
} | parameter_type_list T_COMMA parameter {
$$ = $1;
$3->next = $$->u.function.parameters;
$$->u.function.parameters = $3;
}
parens: T_LPAREN parameter_type_list varargs T_RPAREN {
$2->u.function.parameters = reverse_decls($2->u.function.parameters);
$2->u.function.variadic = $3;
$$ = $2;
} | T_LPAREN declarator_ish T_RPAREN {
struct cdecl *fake_params;
ALLOC_DECL(fake_params, NULL, $2);
ALLOC_FUNCTION_($$, fake_params);
}
pointer: T_ASTERISK qualifiers direct_declarator {
ALLOC_POINTER($$, $2, $3);
} | T_ASTERISK qualifiers pointer {
ALLOC_POINTER($$, $2, $3);
}
declarator: direct_declarator | pointer
declarator_ish: direct_declarator_ish | pointer
postfix: array | parens
direct_declarator_ish: {
$$ = NULLDECL;
} | direct_declarator_ish postfix {
$$ = $2;
$$->child = $1;
}
direct_declarator: {
$$ = NULLDECL;
} | T_IDENT {
$$ = &$1->u.declarator;
} | direct_declarator postfix {
$$ = $2;
$$->child = $1;
}
english: T_DECLARE T_IDENT T_AS english_declaration {
$$ = insert_identifier($4, $2);
} | T_TYPE english_declaration {
$$ = $2;
}
/*
* We use a precedence declaration to prefer shifting an identifier
* over reducing this empty rule; see below.
*/
storage_func_specs: %prec T_TYPE { $$ = NULL; }
storage_func_specs: storage_func_specs declspec_simple {
ALLOC_DECLSPEC($$, $2);
$$->next = $1;
}
type_qual_spec: typespec_noid | qualifier
type_qual_specs: { $$ = NULL; } | type_qual_specs type_qual_spec {
$$ = $2;
$$->next = $1;
}
/*
* The "qualifiers" nonterminal needs to be used here to avoid shift/reduce
* conflicts with pointer declarators. So we end up needing to stitch
* together three different specifiers lists.
*/
post_specs: qualifiers typespec type_qual_specs {
$$ = join_specs3($1, $2, $3);
}
english_declaration: storage_func_specs english_declarator post_specs {
join_specs($3, $1);
ALLOC_DECL($$, $3, $2);
}
english_declarator: {
$$ = NULLDECL;
} | english_declarator qualifiers T_POINTER T_TO {
ALLOC_POINTER($$, $2, $1);
} | english_declarator english_array {
$$ = $2;
$$->child = $1;
} | english_declarator english_function {
$$ = $2;
$$->child = $1;
}
english_function: T_FUNCTION T_RETURNING {
ALLOC_FUNCTION($$, NULL, false);
} | T_FUNCTION T_LPAREN english_parameter_list varargs T_RPAREN T_RETURNING {
$3->u.function.parameters = reverse_decls($3->u.function.parameters);
$3->u.function.variadic = $4;
$$ = $3;
}
english_parameter_list: english_parameter {
ALLOC_FUNCTION_($$, $1);
} | english_parameter_list T_COMMA english_parameter {
$$ = $1;
$3->next = $$->u.function.parameters;
$$->u.function.parameters = $3;
}
typedef_name_qual: T_IDENT qualifiers {
/* Compiler should be able to elide this assignment. */
$1->u.declspec.ident = $1->u.declarator.u.ident;
$$ = &$1->u.declspec;
$$->type = CDECL_TYPE_IDENT;
$$->next = $2;
}
null_decl: {
$$ = NULLDECL;
}
/*
* There is a shift/reduce conflict here when an identifier appears as the
* first token. The conflict is between shifting T_IDENT, or reducing the
* empty production for storage_func_specs (cf. english_declaration).
*
* - In either case, if we reduce, we won't match T_IDENT T_AS since the
* stack now has the extra storage_func_specs nonterminal symbol.
* - And if we shift, we won't match english_declaration since it is
* too late to add storage_func_specs to the stack.
*
* The only valid input affected by the conflict is a simple type names,
* possibly followed by qualifiers. So the conflict is adequately resolved
* by shifting, so long as we have a special-case reduction to handle this.
*/
english_parameter: english_declaration | typedef_name_qual null_decl {
ALLOC_DECL($$, $1, $2);
} | T_IDENT T_AS english_declaration {
$$ = insert_identifier($3, $1);
}
english_array: T_VLA T_ARRAY english_vla T_OF {
$$ = &$3->u.declarator;
$$->type = CDECL_DECL_ARRAY;
$$->u.array.vla = $$->u.ident;
$$->u.array.length = 0;
} | T_ARRAY array_length T_OF {
ALLOC_ARRAY($$, $2);
}
array_length: { $$ = 0; }
array_length: T_UINT {
if (!($$ = $1)) {
cdecl__errmsg(CDECL__EZEROARRAY);
YYERROR;
}
}
english_vla: T_IDENT | {
if (!($$ = cdecl__alloc_item(1)))
YYERROR;
*$$->s = 0;
}
%%
/*
* Expose the token string table to the rest of the library, in order to
* produce strings that match parser keywords.
*
* In order for this to work properly, the Bison output must be postprocessed
* by fix-yytname.awk to remove pointless quotation marks from the keyword
* strings.
*/
const char *cdecl__token_name(unsigned token)
{
return yytname[YYTRANSLATE(token)];
}
/*
* Current versions of GCC (up to 13) want to inline this function into the
* parser even when optimizing for size and the results are not great, so
* try to prevent such inlining.
*/
CDECL__NOINLINE static void
yyerror(YYLTYPE *loc, yyscan_t scanner, struct cdecl **out, const char *err)
{
if (strstr(err, yytname[YYTRANSLATE(T_LEX_ERROR)]))
return;
cdecl__err("%s", err);
}