gio: add g_async_result_is_tagged()

Rather than doing a two step first-check-the-GAsyncResult-subtype-then-
check-the-tag, add a GAsyncResult-level method so that you can do them
both at once, simplifying the code for "short-circuit" async return
values where the vmethod never gets called.

https://bugzilla.gnome.org/show_bug.cgi?id=661767

1 files changed, 3 insertions, 8 deletions

diff --git a/gio/gfileenumerator.c b/gio/gfileenumerator.c
index b4f742463..a6db242fa 100644
--- a/gio/gfileenumerator.c
+++ b/gio/gfileenumerator.c
@@ -400,21 +400,16 @@ g_file_enumerator_next_files_finish (GFileEnumerator  *enumerator,
 				     GError          **error)
 {
   GFileEnumeratorClass *class;
-  GSimpleAsyncResult *simple;
   
   g_return_val_if_fail (G_IS_FILE_ENUMERATOR (enumerator), NULL);
   g_return_val_if_fail (G_IS_ASYNC_RESULT (result), NULL);
   
   if (g_async_result_legacy_propagate_error (result, error))
     return NULL;
-
-  if (G_IS_SIMPLE_ASYNC_RESULT (result))
-    {
-      simple = G_SIMPLE_ASYNC_RESULT (result);
-      
+  else if (g_async_result_is_tagged (result, g_file_enumerator_next_files_async))
+    { 
       /* Special case read of 0 files */
-      if (g_simple_async_result_get_source_tag (simple) == g_file_enumerator_next_files_async)
-	return NULL;
+      return NULL;
     }
   
   class = G_FILE_ENUMERATOR_GET_CLASS (enumerator);