}
/*
- * 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.
+ * The main 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 either an identifier enclosed thrice in parentheses, or an abstract
+ * function declarator enclosed twice in parentheses.
*
- * 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).
+ * To avoid ambiguities, the main parser actually returns a function declarator
+ * for every pair of parentheses. The ones we need to look at consist of a
+ * single parameter with an empty specifier list (noting that every real
+ * 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.
+ * There are two cases:
+ *
+ * - For (), the parser emits a parameter with a lone null declarator.
+ * This fake parameter simply gets deleted, leaving us with a normal
+ * function declarator with an empty identifier list.
+ *
+ * - Otherwise, the parameter's outermost declarator is not null. The
+ * function itself is deleted, replaced in the parse tree with the
+ * fake parameter's declarator.
+ *
+ * Repeating until there no fake parameters, this reduction transforms, for
+ * example, "(((x)))" into "(x)", an abstract function declarator. The result
+ * is then subject to the function simplification step, which will turn "(x)"
+ * into x (declaring an identifier).
+ *
+ * The whole process is repeated until no more changes are made to the parse
+ * tree, or a syntax error is detected.
*/
-
-static int
-reduce_parentheses(struct cdecl_declarator **p, struct cdecl_declarator *d)
+static struct cdecl *fake_function_param(struct cdecl_declarator *d)
{
struct cdecl *param;
if (d->type != CDECL_DECL_FUNCTION)
- return 0;
+ return NULL;
param = d->u.function.parameters;
- if (param && param->specifiers == NULL) {
- struct cdecl_declarator *decl;
+ if (!param || param->specifiers)
+ return NULL;
- assert(!param->next);
+ assert(!param->next);
+ return param;
+}
- decl = param->declarators;
- if (decl->type == CDECL_DECL_NULL) {
- free(decl);
- free(param);
- d->u.function.parameters = NULL;
- return 0;
- }
+static int
+reduce_parentheses(struct cdecl_declarator **p, struct cdecl_declarator *d)
+{
+ struct cdecl *param;
- if (d->child->type != CDECL_DECL_NULL) {
- cdecl__errmsg(CDECL__EBADPARAM);
- return -1;
- }
+ do {
+ d = *p;
+ while ((param = fake_function_param(d))) {
+ struct cdecl_declarator *decl = param->declarators;
+ d->u.function.parameters = NULL;
- free(d->child);
- free(param);
- free(d);
- *p = decl;
+ if (decl->type != CDECL_DECL_NULL) {
+ if (d->child->type != CDECL_DECL_NULL) {
+ /* Fake parameter on real function. */
+ d->u.function.parameters = param;
+ cdecl__errmsg(CDECL__EBADPARAM);
+ return -1;
+ }
- /*
- * We may have replaced d with another fake function which
- * also needs to be eliminated.
- */
- if (reduce_parentheses(p, decl) < 0)
- return -1;
+ param->declarators = d;
+ *p = d = decl;
+ }
- /*
- * 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)) {
- cdecl__errmsg(CDECL__EMANYPAREN);
- return -1;
+ cdecl__free(param);
}
-
- return 1;
- }
+ } while (simplify_functions(p, d));
return 0;
}
/*
- * Function parameters and return types have a few restrictions that are
- * really easy to check in comparison to the above absurdity.
+ * Returns nonzero iff the given specifier list contains a specifier
+ * of the indicated type.
*/
-static int
-check_parameters(struct cdecl_declarator **p, struct cdecl_declarator *d)
+static int have_specifier(struct cdecl_declspec *s, unsigned type)
{
- struct cdecl_declspec *spec;
- struct cdecl *param;
-
- 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) {
- cdecl__errmsg(CDECL__EVOIDPARAM);
- return -1;
- } else if (d->u.function.parameters->next) {
- cdecl__errmsg(CDECL__EVOIDPARAM);
- return -1;
- } else if (d->u.function.variadic) {
- cdecl__errmsg(CDECL__EVOIDPARAM);
- return -1;
- }
- }
- }
-
+ for (; s; s = s->next)
+ if (s->type == type)
+ 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.
+ * Check syntax restrictions on a function declarator's child declarator.
+ * That is, "pointer to function", "array of function" and "function
+ * returning function".
+ *
+ * Returns -1 if the declaration is invalid, or 0 otherwise.
*/
-static int
-check_rettypes(struct cdecl_declarator **p, struct cdecl_declarator *d)
+static int check_function_child(struct cdecl_declarator *d)
{
- if (!d->child || d->child->type != CDECL_DECL_FUNCTION)
- return 0;
+ struct cdecl_pointer *ptr;
switch (d->type) {
+ case CDECL_DECL_POINTER:
+ ptr = &d->u.pointer;
+ if (have_specifier(ptr->qualifiers, CDECL_QUAL_RESTRICT)) {
+ /* pointer to function cannot be restrict qualified. */
+ cdecl__errmsg(CDECL__ERESTRICTFUNC);
+ return -1;
+ }
+ return 0;
case CDECL_DECL_FUNCTION:
+ /* function returning function is never allowed. */
cdecl__errmsg(CDECL__ERETFUNC);
return -1;
case CDECL_DECL_ARRAY:
- cdecl__errmsg(CDECL__ERETARRAY);
+ /* array of function is never allowed. */
+ cdecl__errmsg(CDECL__EFUNCARRAY);
return -1;
}
return 0;
}
-static int
-check_arrays(struct cdecl_declarator **p, struct cdecl_declarator *d)
+/*
+ * Check a function parameter declaration for validity, which means it has a
+ * valid combination of declaration specifiers and, if it is a void parameter,
+ * that it is the one special case where this is allowed.
+ *
+ * Returns -1 if the declaration is invalid, or 0 otherwise.
+ */
+static int check_function_param(struct cdecl_function *f, struct cdecl *param)
{
- if (!d->child || d->child->type != CDECL_DECL_ARRAY)
- return 0;
-
- switch (d->type) {
- case CDECL_DECL_FUNCTION:
- cdecl__errmsg(CDECL__EFUNCARRAY);
+ if (!valid_declspecs(param, false))
return -1;
+
+ /* Check for "void" function parameters as a special case. */
+ if (param->declarators->type == CDECL_DECL_NULL
+ && have_specifier(param->specifiers, CDECL_TYPE_VOID))
+ {
+ struct cdecl *fp = f->parameters;
+
+ if (f->variadic || fp->next || fp->specifiers->next) {
+ cdecl__errmsg(CDECL__EVOIDPARAM);
+ return -1;
+ }
}
return 0;
}
-static int
-normalize_specs(struct cdecl_declarator **p, struct cdecl_declarator *d)
+/*
+ * Normalize the specifier lists for function parameters, and then check the
+ * function declarator for validity.
+ *
+ * Returns -1 if the declaration is invalid, or 0 otherwise.
+ */
+static int postproc_function(struct cdecl_declarator *d)
{
- struct cdecl_function *func;
- struct cdecl_pointer *ptr;
+ struct cdecl_function *func = &d->u.function;
+ struct cdecl *param;
+ int rc;
- 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;
+ for (param = func->parameters; param; param = param->next) {
+ param->specifiers = cdecl__normalize_specs(param->specifiers);
+
+ if ((rc = check_function_param(func, param)) < 0)
+ return rc;
}
- return 0;
+ return check_function_child(d->child);
}
static int
-check_qualifiers(struct cdecl_declarator **p, struct cdecl_declarator *d)
+postproc_common(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)
+ switch (d->type) {
+ case CDECL_DECL_POINTER:
+ ptr = &d->u.pointer;
+ ptr->qualifiers = cdecl__normalize_specs(ptr->qualifiers);
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) {
- cdecl__errmsg(CDECL__ERESTRICTFUNC);
+ case CDECL_DECL_FUNCTION:
+ return postproc_function(d);
+ case CDECL_DECL_ARRAY:
+ if (d->child && d->child->type == CDECL_DECL_FUNCTION) {
+ /* function returning array is never allowed. */
+ cdecl__errmsg(CDECL__ERETARRAY);
return -1;
}
+ return 0;
}
return 0;
* 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.
+ *
+ * The called function may return a negative value to indicate an error
+ * which terminates traversal.
+ *
+ * Returns 0 on success, or a negative value on failure.
*/
-static bool forall_declarators(struct cdecl *decl,
+static int 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);
- }
+ for (p = &decl->declarators; *p; p = &d->child) {
+ int rc;
+
+ rc = f(p, *p);
+ if (rc < 0)
+ return rc;
+ d = *p;
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;
+ rc = forall_declarators(i, f);
+ if (rc < 0)
+ return rc;
}
}
}
- return true;
+ return 0;
}
static struct cdecl *do_parse(const char *str, int english_mode)
return decl;
}
-struct cdecl *cdecl_parse_decl(const char *declstr)
+static int do_postprocess(struct cdecl *decl, int english_mode)
{
struct cdecl_declspec *norm_specs;
- struct cdecl *decl;
-
- if (!(decl = do_parse(declstr, false)))
- return NULL;
+ struct cdecl *i;
/*
- * 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.
+ * For a C declaration with more than one full declarator, the
+ * specifier list is common to all of them. Normalize it once,
+ * then propagate that to all the linked cdecl structures.
+ *
+ * In english mode, the cdecl structure list always has exactly
+ * one entry so we don't need to do anything differently.
*/
norm_specs = cdecl__normalize_specs(decl->specifiers);
- for (struct cdecl *i = decl; i; i = i->next) {
+ for (i = decl; i; i = i->next)
i->specifiers = norm_specs;
- }
- /* Now perform checks and simplifications on each declarator. */
- for (struct cdecl *i = decl; i; i = i->next) {
- 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;
+ for (i = decl; i; i = i->next) {
+ if (!english_mode) {
+ if (forall_declarators(i, reduce_parentheses) < 0)
+ return 0;
+ }
+
+ if (forall_declarators(i, postproc_common) < 0)
+ return 0;
if (!valid_declspecs(i, true))
- goto err;
+ return 0;
- if (cdecl_is_abstract(i->declarators)
- && (i != decl || i->next)) {
+ if (decl->next && cdecl_is_abstract(i->declarators)) {
+ /* Abstract full declarators: there can only be one. */
cdecl__errmsg(CDECL__EDECLTYPE);
- goto err;
+ return 0;
}
}
- return decl;
-err:
- cdecl__free(decl);
- return NULL;
+ return 1;
}
-struct cdecl *cdecl_parse_english(const char *english)
+static struct cdecl *parse_common(const char *str, int english_mode)
{
struct cdecl *decl;
- if (!(decl = do_parse(english, true)))
+ if (!(decl = do_parse(str, english_mode)))
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;
+ if (!do_postprocess(decl, english_mode)) {
+ cdecl__free(decl);
+ return NULL;
}
return decl;
-err:
- cdecl__free(decl);
- return NULL;
+}
+
+struct cdecl *cdecl_parse_decl(const char *declstr)
+{
+ return parse_common(declstr, false);
+}
+
+struct cdecl *cdecl_parse_english(const char *english)
+{
+ return parse_common(english, true);
}
void cdecl_free(struct cdecl *decl)
projects / cdecl99.git / blobdiff