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   "slur",
  31   0
  32 };
  33
  34 bool
  35 Voice_devnull_engraver::try_music (Music *m)
  36 {
  37   SCM s = get_property ("devNullVoice");
  38 #if 0
  39   /* No need */
  40   if (gh_equal_p (s, ly_symbol2scm ("never")))
  41     return;
  42 #endif
  43
  44   if (gh_equal_p (s, ly_symbol2scm ("allways"))
  45       || (s == SCM_EOL
  46           && daddy_trans_l_->id_str_.left_str (3) == "two"
  47           && (to_boolean (get_property ("unison"))
  48               || to_boolean (get_property ("unisilence")))))
  49     {
  50       if (Span_req *s = dynamic_cast <Span_req *> (m))
  51         {
  52           SCM t = s->get_mus_property ("span-type");
  53
  54           for (char const **p = eat_spanners; *p; p++)
  55             {
  56               if (t == ly_str02scm (*p))
  57                 return true;
  58             }
  59         }
  60       /* Ugh.  Should eat other requests, script etc. too. */
  61       else if (dynamic_cast<Tie_req*> (m))
  62         return true;
  63     }
  64   return false;
  65 }
  66
  67 static char const *junk_interfaces[] = {
  68   "beam-interface",
  69   "dynamic-interface",
  70   "hairpin-interface",
  71   "multi-measure-rest-interface",
  72   "script-interface",
  73   "slur-interface",
  74   "text-interface",
  75   "text-item-interface",
  76   "text-script-interface",
  77   "text-spanner-interface",
  78   "tie-interface",
  79   0
  80 };
  81
  82 void
  83 Voice_devnull_engraver::acknowledge_grob (Grob_info i)
  84 {
  85   SCM s = get_property ("devNullVoice");
  86 #if 0
  87   /* No need, next if will never be true */
  88   if (s == ly_symbol2scm ("never"))
  89     return;
  90 #endif
  91
  92   if (s == ly_symbol2scm ("allways")
  93       || (s == SCM_EOL
  94           && daddy_trans_l_->id_str_.left_str (3) == "two"
  95           && (to_boolean (get_property ("unison"))
  96               || to_boolean (get_property ("unisilence")))))
  97     for (char const **p = junk_interfaces; *p; p++)
  98       if (i.grob_l_->has_interface (ly_symbol2scm (*p)))
  99         {
 100 #if 0
 101           /* Ugh: virtual mmrest::suicide () ? */
 102           if (i.grob_l_->has_interface (ly_symbol2scm ("multi-measure-rest-interface")))
 103             i.grob_l_->set_grob_property ("skip-timestep", SCM_BOOL_T);
 104           else
 105             ;
 106 #endif
 107           /* Ugh, we can suicide them, but they remain living */
 108           i.grob_l_->suicide ();
 109           return;
 110         }
 111 }
 112
 113 Voice_devnull_engraver::Voice_devnull_engraver(){}
 114
 115 ENTER_DESCRIPTION(Voice_devnull_engraver,
 116 /* descr */       "Kill off certain items and spanners if we're Voice `two' and unison or unisilence is set.",
 117 /* creats*/       "",
 118 /* acks  */       "grob-interface",
 119 /* reads */       "",
 120 /* write */       "");