+void
+Translator::connect_to_context (Context *c)
+{
+ for (translator_listener_record *r = get_listener_list (); r; r=r->next_)
+ c->events_below ()->add_listener (r->get_listener_ (this), r->event_class_);
+}
+
+void
+Translator::disconnect_from_context (Context *c)
+{
+ for (translator_listener_record *r = get_listener_list (); r; r=r->next_)
+ c->events_below ()->remove_listener (r->get_listener_ (this), r->event_class_);
+}
+
+static SCM listened_event_class_table;
+void
+ensure_listened_hash ()
+{
+ if (!listened_event_class_table)
+ listened_event_class_table = scm_permanent_object (scm_c_make_hash_table (61));
+}
+
+
+LY_DEFINE (ly_get_listened_event_classes, "ly:get-listened-event-classes",
+ 0, 0, 0, (),
+ "Return a list of all event classes that some translator listens"
+ " to.")
+{
+ ensure_listened_hash ();
+ return ly_hash_table_keys (listened_event_class_table);
+}
+
+LY_DEFINE (ly_is_listened_event_class, "ly:is-listened-event-class",
+ 1, 0, 0, (SCM sym),
+ "Is @var{sym} a listened event class?")
+{
+ ensure_listened_hash ();
+ return scm_hashq_ref (listened_event_class_table, sym, SCM_BOOL_F);
+}
+
+void
+add_listened_event_class (SCM sym)
+{
+ ensure_listened_hash ();
+ scm_hashq_set_x (listened_event_class_table, sym, SCM_BOOL_T);
+}
+
+
+/*
+ internally called once, statically, for each translator
+ listener. Connects the name of an event class with a procedure that
+ fetches the corresponding listener.
+
+ The method should only be called from the macro
+ IMPLEMENT_TRANSLATOR_LISTENER.
+ */
+void
+Translator::add_translator_listener (translator_listener_record **listener_list,
+ translator_listener_record *r,
+ Listener (*get_listener) (void *),
+ const char *ev_class)
+{
+ /* ev_class is the C++ identifier name. Convert to scm symbol */
+ string name = string (ev_class);
+ name = replace_all (&name, '_', '-');
+ name += "-event";
+
+ SCM class_sym = scm_str2symbol (name.c_str ());
+
+ add_listened_event_class (class_sym);
+
+ r->event_class_ = class_sym;
+ r->get_listener_ = get_listener;
+ r->next_ = *listener_list;
+ *listener_list = r;
+}
+
+/*
+ Helps the individual static_translator_description methods of translators.
+*/
+SCM
+Translator::static_translator_description (const char *grobs,
+ const char *desc,
+ translator_listener_record *listener_list,
+ const char *read,
+ const char *write) const
+{
+ SCM static_properties = SCM_EOL;
+
+ static_properties = scm_acons (ly_symbol2scm ("grobs-created"),
+ parse_symbol_list (grobs), static_properties);
+
+ static_properties = scm_acons (ly_symbol2scm ("description"),
+ scm_from_locale_string (desc), static_properties);
+
+ SCM list = SCM_EOL;
+ for (; listener_list; listener_list = listener_list->next_)
+ list = scm_cons (listener_list->event_class_, list);
+ static_properties = scm_acons (ly_symbol2scm ("events-accepted"),
+ list, static_properties);
+
+ static_properties = scm_acons (ly_symbol2scm ("properties-read"),
+ parse_symbol_list (read), static_properties);
+
+ static_properties = scm_acons (ly_symbol2scm ("properties-written"),
+ parse_symbol_list (write), static_properties);
+
+ return static_properties;
+}
+