- Added function to apply a custom filter on plugin features

Original commit message from CVS:
- Added function to apply a custom filter on plugin features

gst/gstregistrypool.c

@@ -146,6 +146,15 @@ gst_registry_pool_plugin_list (void)
   return g_list_concat (_gst_registry_pool_plugins, result);
 }
 
+GstFeatureFilterResult
+gst_registry_pool_feature_type_filter (GstPluginFeature *feature, GType type)
+{
+  if (type == 0 || G_OBJECT_TYPE (feature) == type)
+    return GST_FEATURE_FILTER_OK;
+
+  return GST_FEATURE_FILTER_NOK;
+}
+
 /**
  * gst_registry_pool_feature_list:
  * @type: the type of the features to list.
@@ -157,28 +166,66 @@ gst_registry_pool_plugin_list (void)
 GList*
 gst_registry_pool_feature_list (GType type)
 {
-  GList *result = NULL;
+  return gst_registry_pool_feature_filter (
-  GList *plugins = gst_registry_pool_plugin_list ();
+		  (GstPluginFeatureFilter) gst_registry_pool_feature_type_filter, 
+		  GINT_TO_POINTER (type));
+}
 
-  while (plugins) {
+/**
+ * gst_registry_pool_feature_filter:
+ * @filter: the filter to apply to the feature list
+ * @user_data: data passed to the filter function
+ *
+ * Apply the filter function to all features and return a list
+ * of those features that satisfy the filter.
+ * 
+ * Returns: a GList of pluginfeatures, g_list_free after use.
+ */
+GList*
+gst_registry_pool_feature_filter (GstPluginFeatureFilter filter, gpointer user_data)
+{
+  GList *result = NULL;
+  GList *plugins, *orig;
+  gboolean done = FALSE;
+
+  orig = plugins = gst_registry_pool_plugin_list ();
+
+  while (plugins && !done) {
     GstPlugin *plugin = GST_PLUGIN (plugins->data);
     GList *features = plugin->features;
       
-    while (features) {
-      GstPluginFeature *feature = GST_PLUGIN_FEATURE (features->data);
-
-      if (type == 0 || G_OBJECT_TYPE (feature) == type) {
-        result = g_list_prepend (result, feature);
-      }
-      features = g_list_next (features);
-    }
     plugins = g_list_next (plugins);
+
+    while (features && !done) {
+      GstPluginFeature *feature = GST_PLUGIN_FEATURE (features->data);
+      gboolean res = GST_FEATURE_FILTER_OK;
+
+      features = g_list_next (features);
+
+      if (filter)
+        res = filter (feature, user_data);
+
+      switch (res) {
+	case GST_FEATURE_FILTER_DONE:
+	  done = TRUE;
+	  /* fallthrough */
+	case GST_FEATURE_FILTER_OK:
+          result = g_list_prepend (result, feature);
+          break;
+	case GST_FEATURE_FILTER_NOK:
+	default:
+          break;
+      }
+    }
   }
   result = g_list_reverse (result);
 
+  g_list_free (orig);
+  
   return result;
 }
 
+
 /**
  * gst_registry_pool_find_plugin:
  * @name: the name of the plugin to find

gst/gstregistrypool.h

@@ -28,6 +28,17 @@
 
 G_BEGIN_DECLS
 
+typedef enum
+{
+  GST_FEATURE_FILTER_OK,	/* include feature in list */
+  GST_FEATURE_FILTER_NOK,	/* does not include filter in list */
+  GST_FEATURE_FILTER_DONE,	/* includes filter in list and stop processing */
+} GstFeatureFilterResult;
+
+typedef GstFeatureFilterResult (*GstPluginFeatureFilter) 	(GstPluginFeature *feature, 
+		 						 gpointer user_data);
+
+
 /* the pool of registries */
 GList*			gst_registry_pool_list		(void);
 void			gst_registry_pool_add		(GstRegistry *registry, guint priority);
@@ -39,6 +50,10 @@ void			gst_registry_pool_load_all	(void);
 
 GList*			gst_registry_pool_plugin_list	(void);
 GList*			gst_registry_pool_feature_list	(GType type);
+GList*			gst_registry_pool_feature_filter (GstPluginFeatureFilter filter, gpointer user_data);
+
+GstFeatureFilterResult 	gst_registry_pool_feature_type_filter (GstPluginFeature *feature, GType type);
+
 
 GstPlugin*		gst_registry_pool_find_plugin	(const gchar *name);
 GstPluginFeature*	gst_registry_pool_find_feature	(const gchar *name, GType type);