+ // never become a task. Instead e.g. by a listener pool we should visit
+ // all listeners one by one
+ }
+
+ /**
+ * Query visitor method for active queries
+ *
+ * @param $queryInstance A Queryable instance
+ * @return void
+ * @todo Does a query needs to perform some actions as an active task?
+ */
+ public function visitQuery (Queryable $queryInstance) {
+ // Empty for now...
+ }
+
+ /**
+ * Visits the given listener instance
+ *
+ * @param $listenerInstance A Listenable instance
+ * @return void
+ */
+ public function visitListener (Listenable $listenerInstance) {
+ // Do "listen" here
+ $listenerInstance->doListen();
+ }
+
+ /**
+ * Visits the given decorator instance
+ *
+ * @param $decoratorInstance A decorator instance
+ * @return void
+ */
+ public function visitDecorator (BaseDecorator $decoratorInstance) {
+ // A decorator itself can never bevome an active task so this method
+ // remains empty.