lily/voice-devnull-engraver.cc

   1 /*
   2   voice-devnull-engraver.cc -- implement Voice_devnull_engraver
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c) 2000--2002 Jan Nieuwenhuizen <janneke@gnu.org>
   7 */
   8
   9 #include "engraver.hh"
  10 #include "item.hh"
  11 #include "musical-request.hh"
  12 #include "translator-group.hh"
  13
  14 class Voice_devnull_engraver : public Engraver
  15 {
  16 public:
  17   TRANSLATOR_DECLARATIONS(Voice_devnull_engraver);
  18
  19 protected:
  20   virtual bool try_music (Music *m);
  21   virtual void acknowledge_grob (Grob_info);
  22 };
  23
  24
  25
  26 static char const *eat_spanners[] = {
  27   "beam",
  28   "crescendo",
  29   "decrescendo",
  30   "rest",
  31   "slur",
  32   0
  33 };
  34
  35 bool
  36 Voice_devnull_engraver::try_music (Music *m)
  37 {
  38   SCM s = get_property ("devNullVoice");
  39 #if 0
  40   /* No need */
  41   if (gh_equal_p (s, ly_symbol2scm ("never")))
  42     return;
  43 #endif
  44
  45   if (gh_equal_p (s, ly_symbol2scm ("allways"))
  46       || (s == SCM_EOL
  47           && daddy_trans_l_->id_str_.left_str (3) == "two"
  48           && (to_boolean (get_property ("unison"))
  49               || to_boolean (get_property ("unisilence")))))
  50     {
  51       if (Span_req *s = dynamic_cast <Span_req *> (m))
  52         {
  53           SCM t = s->get_mus_property ("span-type");
  54
  55           for (char const **p = eat_spanners; *p; p++)
  56             {
  57               if (t == ly_str02scm (*p))
  58                 return true;
  59             }
  60         }
  61       /* Ugh.  Should eat other requests, script etc. too. */
  62       else if (dynamic_cast<Tie_req*> (m))
  63         return true;
  64     }
  65   return false;
  66 }
  67
  68 static char const *junk_interfaces[] = {
  69   "beam-interface",
  70   "dynamic-interface",
  71   "hairpin-interface",
  72   "multi-measure-rest-interface",
  73   "script-interface",
  74   "slur-interface",
  75   "text-interface",
  76   "text-item-interface",
  77   "text-script-interface",
  78   "text-spanner-interface",
  79   "tie-interface",
  80   0
  81 };
  82
  83 void
  84 Voice_devnull_engraver::acknowledge_grob (Grob_info i)
  85 {
  86   SCM s = get_property ("devNullVoice");
  87 #if 0
  88   /* No need, next if will never be true */
  89   if (s == ly_symbol2scm ("never"))
  90     return;
  91 #endif
  92
  93   if (s == ly_symbol2scm ("allways")
  94       || (s == SCM_EOL
  95           && daddy_trans_l_->id_str_.left_str (3) == "two"
  96           && (to_boolean (get_property ("unison"))
  97               || to_boolean (get_property ("unisilence")))))
  98     for (char const **p = junk_interfaces; *p; p++)
  99       if (i.grob_l_->internal_has_interface (ly_symbol2scm (*p)))
 100         {
 101           /* Ugh, we can suicide them, but they remain living */
 102           i.grob_l_->suicide ();
 103           return;
 104         }
 105 }
 106
 107 Voice_devnull_engraver::Voice_devnull_engraver(){}
 108
 109 ENTER_DESCRIPTION(Voice_devnull_engraver,
 110 /* descr */       "Kill off certain items and spanners if we're Voice `two' and unison or unisilence is set.",
 111 /* creats*/       "",
 112 /* acks  */       "grob-interface",
 113 /* reads */       "",
 114 /* write */       "");