libcdecl: Use macros for packing tokens into bytes.

[cdecl99.git] / src / parse-decl.c

diff --git a/src/parse-decl.c b/src/parse-decl.c
index 3137859708b5745d24ec489309efd97a0edfdd69..a6204a18a00c32b524d9bc5dc89cff67cc5b7905 100644 (file)
--- a/src/parse-decl.c
+++ b/src/parse-decl.c
@@ -230,30 +230,40 @@ simplify_functions(struct cdecl_declarator **p, struct cdecl_declarator *d)
        free(d->child);
        free(d);
 
-       return 0;
+       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.
+ * 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 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).
+ *
+ * There are two cases:
  *
- * 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).
+ *   - 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.
  *
- * 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.
+ *   - 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 struct cdecl *fake_function_param(struct cdecl_declarator *d)
 {
        struct cdecl *param;
@@ -273,34 +283,28 @@ static int
 reduce_parentheses(struct cdecl_declarator **p, struct cdecl_declarator *d)
 {
        struct cdecl *param;
-       int fake = 0;
-
-       while ((param = fake_function_param(d))) {
-               struct cdecl_declarator *decl = param->declarators;
-               d->u.function.parameters = NULL;
-
-               if (decl->type != CDECL_DECL_NULL) {
-                       if (d->child->type != CDECL_DECL_NULL) {
-                               /* Found fake parameter on real function. */
-                               d->u.function.parameters = param;
-                               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;
+
+                       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;
+                               }
+
+                               param->declarators = d;
+                               *p = d = decl;
                        }
 
-                       param->declarators = d;
-                       *p = d = decl;
-                       fake = 1;
+                       cdecl__free(param);
                }
-
-               cdecl__free(param);
-       }
-
-       simplify_functions(p, d);
-       if (fake && (*p)->type == CDECL_DECL_FUNCTION) {
-               /* Started with a fake function but ended with a real one. */
-               cdecl__errmsg(CDECL__EMANYPAREN);
-               return -1;
-       }
+       } while (simplify_functions(p, d));
 
        return 0;
 }