lily/output-property-engraver.cc

   1 /*
   2   output-property-engraver.cc --  implement Output_property_engraver
   3
   4   source file of the GNU LilyPond music typesetter
   5
   6   (c) 2000--2002 Han-Wen Nienhuys <hanwen@cs.uu.nl>
   7
   8  */
   9
  10 #include "engraver.hh"
  11 #include "grob.hh"
  12 #include "output-property-music-iterator.hh"
  13
  14 class Output_property_engraver : public Engraver
  15 {
  16 TRANSLATOR_DECLARATIONS(Output_property_engraver);
  17 protected:
  18
  19   /*
  20     should do this with \once and \push ?
  21
  22
  23       \property Voice.outputProperties \push #pred = #modifier
  24
  25       where both MODIFIER and PRED are functions taking a
  26       grob.
  27
  28    */
  29
  30
  31   Link_array<Music> props_;
  32
  33   virtual void stop_translation_timestep ();
  34   virtual void acknowledge_grob (Grob_info);
  35   virtual bool try_music (Music*);
  36 };
  37
  38
  39 bool
  40 Output_property_engraver::try_music (Music* m)
  41 {
  42   if (m->get_mus_property ("iterator-ctor") ==
  43       Output_property_music_iterator::constructor_proc)
  44     {
  45       props_.push (m);
  46       return true;
  47     }
  48   return false;
  49 }
  50
  51 void
  52 Output_property_engraver::acknowledge_grob (Grob_info inf)
  53 {
  54   for (int i=props_.size (); i--;)
  55     {
  56       Music * o = props_[i];
  57       SCM pred = o->get_mus_property ("predicate");
  58
  59       /*
  60         should typecheck pred.
  61        */
  62       SCM result=gh_apply (pred,
  63                            scm_list_n (inf.grob_->self_scm (), SCM_UNDEFINED));
  64       if (to_boolean (result))
  65         {
  66           SCM sym = o->get_mus_property ("grob-property");
  67           SCM val = o->get_mus_property ("grob-value");
  68           inf.grob_->internal_set_grob_property (sym, val);
  69         }
  70     }
  71 }
  72
  73 void
  74 Output_property_engraver::stop_translation_timestep ()
  75 {
  76   props_.clear ();
  77 }
  78
  79 Output_property_engraver::Output_property_engraver()
  80 {
  81 }
  82
  83 ENTER_DESCRIPTION(Output_property_engraver,
  84 /* descr */       "Interpret Music of Output_property type, and apply a function
  85 to any Graphic objects that satisfies the predicate.",
  86 /* creats*/       "",
  87 /* acks  */       "grob-interface",
  88 /* reads */       "",
  89 /* write */       "");