+ADD_ACKNOWLEDGER (Beam_engraver, stem);
+ADD_ACKNOWLEDGER (Beam_engraver, rest);
+
+ADD_TRANSLATOR (Beam_engraver,
+ /* doc */
+ "Handle @code{Beam} events by engraving beams. If omitted,"
+ " then notes are printed with flags instead of beams.",
+
+ /* create */
+ "Beam ",
+
+ /* read */
+ "baseMoment "
+ "beamMelismaBusy "
+ "beatStructure "
+ "subdivideBeams ",
+
+ /* write */
+ "forbidBreak"
+ );
+
+class Grace_beam_engraver : public Beam_engraver
+{
+public:
+ TRANSLATOR_DECLARATIONS (Grace_beam_engraver);
+
+ DECLARE_TRANSLATOR_LISTENER (beam);
+
+protected:
+ virtual bool valid_start_point ();
+ virtual bool valid_end_point ();
+};
+
+Grace_beam_engraver::Grace_beam_engraver ()
+{
+}
+
+bool
+Grace_beam_engraver::valid_start_point ()
+{
+ Moment n = now_mom ();
+
+ return n.grace_part_ != Rational (0);
+}
+
+bool
+Grace_beam_engraver::valid_end_point ()
+{
+ return beam_ && valid_start_point ();
+}
+
+/*
+ Ugh, C&P code.
+ */
+IMPLEMENT_TRANSLATOR_LISTENER (Grace_beam_engraver, beam);
+void
+Grace_beam_engraver::listen_beam (Stream_event *ev)
+{
+ Direction d = to_dir (ev->get_property ("span-direction"));
+
+ if (d == START && valid_start_point ())
+ start_ev_ = ev;
+ else if (d == STOP && valid_end_point ())
+ stop_ev_ = ev;
+}
+
+
+ADD_ACKNOWLEDGER (Grace_beam_engraver, stem);
+ADD_ACKNOWLEDGER (Grace_beam_engraver, rest);
+
+ADD_TRANSLATOR (Grace_beam_engraver,
+ /* doc */
+ "Handle @code{Beam} events by engraving beams. If omitted,"
+ " then notes are printed with flags instead of beams. Only"
+ " engraves beams when we are at grace points in time.",
+
+ /* create */
+ "Beam ",
+
+ /* read */
+ "baseMoment "
+ "beamMelismaBusy "
+ "beatStructure "
+ "subdivideBeams ",
+
+ /* write */
+ ""
+ );
+