/*   
  lyric-number-engraver.cc --  implement Stanza_number_engraver
  
  source file of the GNU LilyPond music typesetter
  
  (c) 2000--2004 Han-Wen Nienhuys <hanwen@cs.uu.nl>, Glen Prideaux <glenprideaux@iname.com>

*/

#include "engraver.hh"
#include "item.hh"
#include "side-position-interface.hh"

class Stanza_number_engraver : public Engraver
{
  Item *text_;

  /*
    This is naughty, since last_stanza_ may be GCd from under us.  But
    since we don't look at the contents, we are/should be (knock on
    wood) OK.
   */
  SCM last_stanza_;
public:
  TRANSLATOR_DECLARATIONS (Stanza_number_engraver);
  virtual void process_music ();
  virtual void stop_translation_timestep ();
  virtual void acknowledge_grob (Grob_info);
};


/*
  TODO: should make engraver that collects all the stanzas on a higher
  level, and then groups them to the side. Stanza numbers should be
  all aligned.
 */

Stanza_number_engraver::Stanza_number_engraver ()
{
  text_ = 0;
}

void
Stanza_number_engraver::process_music ()
{
  SCM stanza = get_property ("stanza");
  
  if (scm_is_string (stanza) && stanza != last_stanza_)
    {
      last_stanza_ = stanza;
      
      text_ = make_item ("StanzaNumber", SCM_EOL);
      text_->set_property ("text", stanza);
      
    }
}


void
Stanza_number_engraver::acknowledge_grob (Grob_info inf)
{
  if (text_
      && inf.grob_->internal_has_interface (ly_symbol2scm ("lyric-syllable-interface")))
    {
      Side_position_interface::add_support (text_, inf.grob_);
    }
}

void
Stanza_number_engraver::stop_translation_timestep ()
{
  text_ = 0;
}


ENTER_DESCRIPTION (Stanza_number_engraver,
/* descr */       "",
/* creats*/       "StanzaNumber",
/* accepts */     "",
/* acks  */      "lyric-syllable-interface",
/* reads */       "stanza",
/* write */       "");
