+/*
+ * Parse and validate C declarations.
+ * Copyright © 2011-2012 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 <http://www.gnu.org/licenses/>.
+ */
+#include <config.h>
#include <stdio.h>
#include <assert.h>
+#include <stdbool.h>
#include "cdecl.h"
#include "typemap.h"
#include "parse.h"
#include "scan.h"
+#include "i18n.h"
+#include "normalize.h"
-static int verify_declspecs(struct cdecl_declspec *s)
+/*
+ * Verify the declaration specifiers of a declaration. If top is true, treat
+ * this as a top-level declaration. Otherwise, treat this as a function
+ * parameter (which carries additional constraints).
+ */
+static bool valid_declspecs(struct cdecl *decl, bool top)
{
+ struct cdecl_declspec *specs = decl->specifiers;
+ struct cdecl_declarator *d = decl->declarators;
+ bool abstract = cdecl_is_abstract(d);
unsigned num_storage = 0;
unsigned long typemap;
- typemap = cdecl__build_typemap(s);
+ typemap = cdecl__build_typemap(specs);
if (typemap == -1)
- return -1;
+ return false;
- for (struct cdecl_declspec *c = s; c; c = c->next) {
+ for (struct cdecl_declspec *c = specs; c; c = c->next) {
switch (cdecl_spec_kind(c)) {
case CDECL_SPEC_TYPE:
+ if (c->type == CDECL_TYPE_VOID &&
+ (d->type == CDECL_DECL_IDENT
+ || d->type == CDECL_DECL_ARRAY)) {
+ fprintf(stderr, "invalid declaration of type void\n");
+ return false;
+ }
continue;
case CDECL_SPEC_STOR:
+ if (top && abstract) {
+ fprintf(stderr, "type names cannot have storage-class specifiers\n");
+ return false;
+ }
+
+ if (!top && c->type != CDECL_STOR_REGISTER) {
+ fprintf(stderr, "function parameters may only have register storage\n");
+ return false;
+ }
+
if (++num_storage > 1) {
fprintf(stderr, "too many storage-class specifiers\n");
- return -1;
+ return false;
}
break;
case CDECL_SPEC_QUAL:
*/
if (c->type == CDECL_QUAL_RESTRICT) {
fprintf(stderr, "only pointer types can be restrict-qualified.\n");
- return -1;
+ return false;
}
break;
case CDECL_SPEC_FUNC:
- /*
- * We don't support functions yet.
- */
- fprintf(stderr, "only function declarations may have function specifiers.\n");
- return -1;
+ if (abstract) {
+ fprintf(stderr, "type names cannot have function specifiers\n");
+ return false;
+ }
+
+ if (!top || d->type != CDECL_DECL_FUNCTION) {
+ fprintf(stderr, "only function declarations may have function specifiers.\n");
+ return false;
+ }
+ break;
default:
assert(0);
}
}
+ return true;
+}
+
+/*
+ * The C grammar leaves ambiguous some cases where parentheses represent a
+ * function declarator or just parentheses. The language uses additional
+ * context (whether or not a typedef is in scope, etc.) to resolve these
+ * ambiguities, but we don't have access to that kind of information.
+ *
+ * The cdecl99 parser uses an unambiguous grammar which treats almost
+ * everything as a function, and thus considers things like 'int (x)' to
+ * be a function type with a single parameter of type 'x' (a typedef name),
+ * returning int. This can result in very complicated types for simple
+ * declarations. Ideally, cdecl99 should try and find the "simplest"
+ * explanation for a given declaration.
+ *
+ * Whether or not it achieves the simplest explanation, we apply a simple rule:
+ * if a declarator could be interpreted as something other than a function,
+ * do that.
+ *
+ * - The function declarator has a null child declarator.
+ * - The function declarator has exactly one parameter, and is not variadic.
+ * - The function parameter has a type specifier, and it is a typedef name.
+ * - The function parameter has no other declaration specifiers.
+ * - The function parameter does not declare an identifier.
+ *
+ * Since cdecl99 supports things like [*] in any context (in C, such constructs
+ * are only valid in function parameter lists), we don't treat them specially
+ * here.
+ */
+
+static struct cdecl_declarator *reduce_function(struct cdecl *param)
+{
+ struct cdecl_declspec *spec = param->specifiers;
+ struct cdecl_declarator *decl = param->declarators;
+ struct cdecl_declarator *last;
+
+ for (last = decl; last && last->type != CDECL_DECL_NULL;)
+ last = last->child;
+
+ if (!last)
+ return NULL;
+
+ last->type = CDECL_DECL_IDENT;
+ last->u.ident = spec->ident;
+ free(param);
+ free(spec);
+
+ return decl;
+}
+
+static bool function_is_reducible(struct cdecl_declarator *d)
+{
+ if (d->type != CDECL_DECL_FUNCTION)
+ return false;
+ if (d->child->type != CDECL_DECL_NULL)
+ return false; /* e.g., int (*)(x) */
+
+ if (!d->u.function.parameters)
+ return false; /* e.g., int f() */
+ if (d->u.function.parameters->next)
+ return false; /* e.g., int (x, y) */
+ if (d->u.function.variadic)
+ return false; /* e.g., int (x, ...) */
+
+ if (d->u.function.parameters->specifiers->type != CDECL_TYPE_IDENT)
+ return false; /* e.g. int (int) */
+ if (d->u.function.parameters->specifiers->next)
+ return false; /* e.g. int (size_t const) */
+
+ return true;
+}
+
+static int
+simplify_functions(struct cdecl_declarator **p, struct cdecl_declarator *d)
+{
+ struct cdecl_declarator *new;
+
+ if (!function_is_reducible(d))
+ return 0;
+
+ new = reduce_function(d->u.function.parameters);
+ if (!new)
+ return 0; /* e.g. int (foo bar) */
+ *p = new;
+ free(d->child);
+ free(d);
+
+ return 1;
+}
+
+/*
+ * The parser's bias towards considering things as functions whenever possible
+ * makes nested parentheses tricky. (x) is considered to be part of a function
+ * declarator until simplify_functions converts it. The problem is that
+ * (((x))) is not valid as part of a function declarator, but it *is* valid
+ * as an identifier enclosed 3 times in parentheses. This is complicated by
+ * the fact that things like (((int))) are not valid anywhere.
+ *
+ * To avoid ambiguities, the parser actually emits a "function" declarator for
+ * every pair of parentheses. The ones that can't reasonably be functions
+ * consist of a single "parameter" with no declaration specifiers (note that
+ * every valid function parameter will have at least one type specifier).
+ *
+ * This pass is to remove these fake functions from the parse tree. We take
+ * care to avoid turning invalid things like ((int)) into valid things like
+ * (int) by observing that the only valid function declarators that appear
+ * in these "fake" parentheses are those that have a non-null child declarator
+ * (for instance, int ((*)(int)) *or* those that will be eliminated by the
+ * simplify_functions pass.
+ */
+
+static int
+reduce_parentheses(struct cdecl_declarator **p, struct cdecl_declarator *d)
+{
+ struct cdecl *param;
+
+ if (d->type != CDECL_DECL_FUNCTION)
+ return 0;
+
+ param = d->u.function.parameters;
+ if (param && param->specifiers == NULL) {
+ struct cdecl_declarator *decl;
+
+ assert(!param->next);
+
+ decl = param->declarators;
+ if (decl->type == CDECL_DECL_NULL) {
+ free(decl);
+ free(param);
+ d->u.function.parameters = NULL;
+ return 0;
+ }
+
+ if (d->child->type != CDECL_DECL_NULL) {
+ fprintf(stderr, "invalid function parameter\n");
+ return -1;
+ }
+
+ free(d->child);
+ free(param);
+ free(d);
+ *p = decl;
+
+ /*
+ * We may have replaced d with another fake function which
+ * also needs to be eliminated.
+ */
+ if (reduce_parentheses(p, decl) < 0)
+ return -1;
+
+ /*
+ * If the remaining declarator is a function, make sure it's
+ * valid by checking its reducibility.
+ */
+ decl = *p;
+ if (decl->type == CDECL_DECL_FUNCTION
+ && decl->child->type == CDECL_DECL_NULL
+ && !function_is_reducible(decl)) {
+ fprintf(stderr, "too many parentheses in function\n");
+ return -1;
+ }
+
+ return 1;
+ }
+
return 0;
}
-static int verify_decl(struct cdecl *decl)
+/*
+ * Function parameters and return types have a few restrictions that are
+ * really easy to check in comparison to the above absurdity.
+ */
+static int
+check_parameters(struct cdecl_declarator **p, struct cdecl_declarator *d)
{
- return verify_declspecs(decl->specifiers);
+ struct cdecl_declspec *spec;
+ struct cdecl *param;
+ bool has_void = false;
+
+ if (d->type != CDECL_DECL_FUNCTION)
+ return 0;
+
+ for (param = d->u.function.parameters; param; param = param->next) {
+ if (!valid_declspecs(param, false))
+ return -1;
+
+ /* Check for "void" function parameters as a special case. */
+ for (spec = param->specifiers; spec; spec = spec->next) {
+ if (param->declarators->type != CDECL_DECL_NULL)
+ continue;
+ if (spec->type != CDECL_TYPE_VOID)
+ continue;
+
+ if (spec != param->specifiers || spec->next != NULL) {
+ fprintf(stderr, "void parameter must not have extra specifiers\n");
+ return -1;
+ } else if (d->u.function.parameters->next) {
+ fprintf(stderr, "a void parameter must stand alone\n");
+ return -1;
+ } else if (d->u.function.variadic) {
+ fprintf(stderr, "variadic functions cannot have a void parameter\n");
+ return -1;
+ }
+ }
+ }
+
+ return 0;
+}
+
+/*
+ * Functions cannot return arrays or functions. Since the parse tree is
+ * "inside-out", we need to look for functions as the child declarator.
+ */
+static int
+check_rettypes(struct cdecl_declarator **p, struct cdecl_declarator *d)
+{
+ if (!d->child || d->child->type != CDECL_DECL_FUNCTION)
+ return 0;
+
+ switch (d->type) {
+ case CDECL_DECL_FUNCTION:
+ fprintf(stderr, "functions cannot return functions\n");
+ return -1;
+ case CDECL_DECL_ARRAY:
+ fprintf(stderr, "functions cannot return arrays\n");
+ return -1;
+ }
+
+ return 0;
+}
+
+static int
+check_arrays(struct cdecl_declarator **p, struct cdecl_declarator *d)
+{
+ if (!d->child || d->child->type != CDECL_DECL_ARRAY)
+ return 0;
+
+ switch (d->type) {
+ case CDECL_DECL_FUNCTION:
+ fprintf(stderr, "array members cannot be functions\n");
+ return -1;
+ }
+
+ return 0;
+}
+
+static int
+normalize_specs(struct cdecl_declarator **p, struct cdecl_declarator *d)
+{
+ struct cdecl_function *func;
+ struct cdecl_pointer *ptr;
+
+ switch (d->type) {
+ case CDECL_DECL_POINTER:
+ ptr = &d->u.pointer;
+ ptr->qualifiers = cdecl__normalize_specs(ptr->qualifiers);
+ break;
+ case CDECL_DECL_FUNCTION:
+ func = &d->u.function;
+ for (struct cdecl *i = func->parameters; i; i = i->next)
+ i->specifiers = cdecl__normalize_specs(i->specifiers);
+ break;
+ }
+
+ return 0;
+}
+
+static int
+check_qualifiers(struct cdecl_declarator **p, struct cdecl_declarator *d)
+{
+ struct cdecl_declspec *spec;
+ struct cdecl_pointer *ptr;
+
+ if (!d->child || d->child->type != CDECL_DECL_POINTER)
+ return 0;
+
+ ptr = &d->child->u.pointer;
+ for (spec = ptr->qualifiers; spec; spec = spec->next) {
+ if (spec->type == CDECL_QUAL_RESTRICT
+ && d->type == CDECL_DECL_FUNCTION) {
+ fprintf(stderr, "function pointers cannot be restrict-qualified\n");
+ return -1;
+ }
+ }
+
+ return 0;
+}
+
+/*
+ * Traverse the parse tree, calling a function on every declarator in a
+ * depth-first preorder traversal. The function is given a pointer to the
+ * declarator as well as to the pointer which was used to reach that
+ * declarator: this can be used to rewrite entire subtrees.
+ */
+static bool forall_declarators(struct cdecl *decl,
+ int f(struct cdecl_declarator **, struct cdecl_declarator *))
+{
+ struct cdecl_declarator *d, **p;
+
+ for (p = &decl->declarators, d = *p; d; p = &d->child, d = *p) {
+ switch (f(p, d)) {
+ case 0:
+ break;
+ case 1:
+ d = *p;
+ break;
+ case -1:
+ return false;
+ default:
+ assert(0);
+ }
+
+ if (d->type == CDECL_DECL_FUNCTION) {
+ struct cdecl *i;
+
+ for (i = d->u.function.parameters; i; i = i->next) {
+ if (!forall_declarators(i, f))
+ return false;
+ }
+ }
+ }
+
+ return true;
}
struct cdecl *cdecl_parse_decl(const char *declstr)
{
+ struct cdecl_declspec *norm_specs;
YY_BUFFER_STATE state;
+ yyscan_t scanner;
struct cdecl *decl;
int rc;
- state = yy_scan_string(declstr);
- rc = yyparse(&decl);
- yy_delete_buffer(state);
+ cdecl__init_i18n();
+ rc = cdecl__yylex_init(&scanner);
if (rc != 0)
return NULL;
- rc = verify_decl(decl);
- if (rc != 0) {
- cdecl_free(decl);
+ state = cdecl__yy_scan_string(declstr, scanner);
+ rc = cdecl__yyparse(scanner, &decl);
+ cdecl__yy_delete_buffer(state, scanner);
+ cdecl__yylex_destroy(scanner);
+
+ if (rc != 0)
return NULL;
+
+ /*
+ * Since the top-level specifiers are shared between each top-level
+ * declarator, we need to normalize them once and then propagate the
+ * new specifier list.
+ */
+ norm_specs = cdecl__normalize_specs(decl->specifiers);
+
+ for (struct cdecl *i = decl; i; i = i->next) {
+ i->specifiers = norm_specs;
+
+ if (!forall_declarators(i, reduce_parentheses))
+ goto err;
+ if (!forall_declarators(i, simplify_functions))
+ goto err;
+ if (!forall_declarators(i, check_parameters))
+ goto err;
+ if (!forall_declarators(i, check_rettypes))
+ goto err;
+ if (!forall_declarators(i, check_arrays))
+ goto err;
+ if (!forall_declarators(i, normalize_specs))
+ goto err;
+ if (!forall_declarators(i, check_qualifiers))
+ goto err;
+
+ if (!valid_declspecs(i, true))
+ goto err;
+
+ if (cdecl_is_abstract(i->declarators)
+ && (i != decl || i->next)) {
+ fprintf(stderr, "mixing type names and declarations is not allowed\n");
+ goto err;
+ }
}
return decl;
+err:
+ cdecl__free(decl);
+ return NULL;
+}
+
+struct cdecl *cdecl_parse_english(const char *english)
+{
+ YY_BUFFER_STATE state;
+ yyscan_t scanner;
+ struct cdecl *decl;
+ int rc;
+
+ cdecl__init_i18n();
+
+ rc = cdecl__yylex_init_extra(true, &scanner);
+ if (rc != 0)
+ return NULL;
+
+ state = cdecl__yy_scan_string(english, scanner);
+ rc = cdecl__yyparse(scanner, &decl);
+ cdecl__yy_delete_buffer(state, scanner);
+ cdecl__yylex_destroy(scanner);
+
+ if (rc != 0)
+ return NULL;
+
+ for (struct cdecl *i = decl; i; i = i->next) {
+ i->specifiers = cdecl__normalize_specs(i->specifiers);
+
+ if (!forall_declarators(i, check_parameters))
+ goto err;
+ if (!forall_declarators(i, check_rettypes))
+ goto err;
+ if (!forall_declarators(i, check_arrays))
+ goto err;
+ if (!forall_declarators(i, normalize_specs))
+ goto err;
+ if (!forall_declarators(i, check_qualifiers))
+ goto err;
+
+ if (!valid_declspecs(i, true))
+ goto err;
+ }
+
+ return decl;
+err:
+ cdecl__free(decl);
+ return NULL;
+}
+
+void cdecl_free(struct cdecl *decl)
+{
+ cdecl__free(decl);
}
projects / cdecl99.git / blobdiff