2 thread-devnull-engraver.cc -- implement Thread_devnull_engraver
4 source file of the GNU LilyPond music typesetter
6 (c) 2000--2002 Jan Nieuwenhuizen <janneke@gnu.org>
11 #include "musical-request.hh"
12 #include "translator-group.hh"
14 class Thread_devnull_engraver : public Engraver
17 TRANSLATOR_DECLARATIONS(Thread_devnull_engraver);
20 virtual void acknowledge_grob (Grob_info);
26 Thread_devnull_engraver::acknowledge_grob (Grob_info i)
28 SCM s = get_property ("devNullThread");
30 /* No need, next if will never be true */
31 if (s == ly_symbol2scm ("never"))
35 if (s == ly_symbol2scm ("allways")
37 && daddy_trans_l_->id_str_.left_str (3) == "two"
38 && (to_boolean (get_property ("unison"))
39 || to_boolean (get_property ("unisilence")))
40 && to_boolean (get_property ("soloADue"))))
42 /* Ugh, we can suicide them, but they remain living */
43 i.grob_l_->suicide ();
46 Thread_devnull_engraver::Thread_devnull_engraver(){}
48 ENTER_DESCRIPTION(Thread_devnull_engraver,
49 /* descr */ "Kill elements whenever we are Voice called `two' and either
50 unison, unisilence or soloADue is set.@footnote{On unix systems, the
51 file @file{/dev/null} is special device: anything written to it is
52 discarded.}. This engraver works closely together with the part
53 combiner. When the part combiner notices that two threads are
54 identical, it tells the @code{Thread_devnull_engraver} to discard
55 everything in the second thread.
58 /* acks */ "grob-interface",