Make arguments like Context.GrobName accessible as symbol lists

lily/footnote-engraver.cc

 /*
   This file is part of LilyPond, the GNU music typesetter.
 
   Copyright (C) 2011--2012 Mike Solomon <mike@mikesolomon.org>
 
   LilyPond is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
 
@@ skipping 15 matching lines @@
 #include "pointer-group-interface.hh"
 #include "spanner.hh"
 #include "system.hh"
 
 #include "translator.icc"
 
 class Footnote_engraver : public Engraver
 {
   TRANSLATOR_DECLARATIONS (Footnote_engraver);
 
-  DECLARE_TRANSLATOR_LISTENER (footnote);
   DECLARE_ACKNOWLEDGER (grob);
   DECLARE_END_ACKNOWLEDGER (grob);
-  vector<Stream_event *> events_;
+
   vector<Drul_array<Spanner *> > annotated_spanners_;
 
-  void stop_translation_timestep ();
   void finalize ();
-  virtual void derived_mark () const;
 
   void footnotify (Grob *, SCM);
 };
 
-IMPLEMENT_TRANSLATOR_LISTENER (Footnote_engraver, footnote);

[Keith, 2012/10/13 05:16:00]

I don't see now the new syntax avoids the need for a listener -- is this
clean-up of unused code ?

[dak, 2012/10/13 07:04:08]

The new syntax allows a grob specification _with_ context, allowing to turn a
"time-based" footnote into a proper override instead of an event.  Since the
tweak-like interpretation of the "footnote-music" field was already in place
previously, this works just as well.

The disadvantage is that you have to specify the context in case of things like
Staff.TimeSignature, just like you would have to do with any override.

The advantage is that this is predictably similar to other operations and does
not require you to juggle the Footnote_engraver between different contexts in
order to have it do its job in difficult circumstances.

So this change of operation is not forced by the new syntax, but rather
facilitated.

Since there is no longer anything generating footnote music events for any
purpose except sticking it into the footnote-music property of grobs, using a
Music data structure at all for storing the footnote data is pretty arbitrary. 
It might be subject to later cleanup, but I wanted to keep the changes
reasonably confined.

This is probably something that is easier to examine in the scope of its change
as a commit in the dev/syntax branch

-void
-Footnote_engraver::listen_footnote (Stream_event *ev)
-{
-  events_.push_back (ev);
-}
-
-void
-Footnote_engraver::stop_translation_timestep ()
-{
-  events_.clear ();
-}
-
 void
 Footnote_engraver::finalize ()
 {
   annotated_spanners_.clear ();
 }
 
-void
-Footnote_engraver::derived_mark () const
-{
-  for (vsize i = 0; i < events_.size (); ++i)
-    scm_gc_mark (events_[i]->self_scm ());
-}
-
 Footnote_engraver::Footnote_engraver ()
 {
 }
 
 void
 Footnote_engraver::footnotify (Grob *g, SCM cause)
 {
   Spanner *s = dynamic_cast<Spanner *>(g);
 
   if (s)
@@ skipping 23 matching lines @@
       if (!mus->is_mus_type ("footnote-event"))
         {
           mus->origin ()->programming_error (_ ("Must be footnote-event."));
           return;
         }
 
       footnotify (info.grob (), mus->to_event (context ())->unprotect ());
 
       // This grob has exhausted its footnote
       info.grob ()->set_property ("footnote-music", SCM_EOL);
+
       return;
     }
-
-  if (!events_.empty ())
-    {
-      string grobname = info.grob ()->name ();
-
-      for (vsize i = 0; i < events_.size (); i++)
-        {
-          SCM name = events_[i]->get_property ("symbol");
-          if (scm_is_symbol (name)
-              && grobname == ly_symbol2string (name))
-            {
-              footnotify (info.grob (), events_[i]->self_scm ());
-              // Event has exhausted its footnote
-              events_[i]->set_property ("symbol", SCM_EOL);
-            }
-        }
-    }
 }
 
 void
 Footnote_engraver::acknowledge_end_grob (Grob_info info)
 {
   Spanner *s = dynamic_cast<Spanner *>(info.grob ());
 
   if (s)
     for (vsize i = 0; i < annotated_spanners_.size (); i++)
       {
@@ skipping 16 matching lines @@
                 /* create */
                 "FootnoteItem "
                 "FootnoteSpanner ",
 
                 /*read*/
                 "currentMusicalColumn ",
 
                 /*write*/
                 ""
                );