+
+ Simple_music_iterator::process (mom);
+}
+
+void
+Property_unset_iterator::process (Moment mom)
+{
+ Context *o = get_outlet ();
+ Music *m = get_music ();
+ bool once = to_boolean (m->get_property ("once"));
+ SCM symbol = m->get_property ("symbol");
+ SCM previous_value = SCM_UNDEFINED;
+ if (once)
+ o->here_defined (symbol, &previous_value);
+
+ send_stream_event (o, "UnsetProperty", m->origin (),
+ ly_symbol2scm ("symbol"), symbol);
+
+ /* For \once \unset install a finalization hook to reset the property to the
+ * previous value after the timestep */
+ if (once && !SCM_UNBNDP (previous_value))
+ {
+ Global_context *tg = get_outlet ()->get_global_context ();
+ tg->add_finalization (scm_list_4 (Property_iterator::once_finalization_proc,
+ o->self_scm (), m->self_scm (),
+ previous_value));
+ }
+
+ Simple_music_iterator::process (mom);
+}
+
+MAKE_SCHEME_CALLBACK (Property_iterator, once_finalization, 3);
+SCM
+Property_iterator::once_finalization (SCM ctx, SCM music, SCM previous_value)
+{
+ Music *m = Music::unsmob (music);
+ Context *c = Context::unsmob (ctx);
+
+ // Do not use UnsetProperty, which sets the default, but rather
+ // cache the value before the \once \set command and restore it now
+ send_stream_event (c, "SetProperty", m->origin (),
+ ly_symbol2scm ("symbol"), m->get_property ("symbol"),
+ ly_symbol2scm ("value"), previous_value);
+
+ return SCM_UNSPECIFIED;
+}
+
+void
+Property_iterator::do_quit ()
+{
+}
+
+bool
+check_grob (Music *mus, SCM sym)
+{
+ bool g = to_boolean (scm_object_property (sym, ly_symbol2scm ("is-grob?")));
+
+ if (!g)
+ mus->origin ()->warning (_f ("not a grob name, `%s'",
+ ly_symbol2string (sym)));
+
+ return g;
+}
+
+SCM
+get_property_path (Music *m)
+{
+ SCM grob_property_path = m->get_property ("grob-property-path");
+
+ SCM eprop = m->get_property ("grob-property");
+ if (scm_is_symbol (eprop))
+ {
+ grob_property_path = scm_list_1 (eprop);
+ }
+
+ return grob_property_path;