Uses single algorithm for side-position spacing.

lily/fingering-engraver.cc

 /*
   This file is part of LilyPond, the GNU music typesetter.
 
   Copyright (C) 1998--2012 Han-Wen Nienhuys <hanwen@xs4all.nl>
 
   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 23 matching lines @@
   vector<Item *> fingerings_;
 
 public:
   TRANSLATOR_DECLARATIONS (Fingering_engraver);
 protected:
   void stop_translation_timestep ();
   void process_music ();
   DECLARE_TRANSLATOR_LISTENER (fingering);
   DECLARE_ACKNOWLEDGER (rhythmic_head);
   DECLARE_ACKNOWLEDGER (stem);
+  DECLARE_ACKNOWLEDGER (flag);
 
 private:
   void make_script (Direction, Stream_event *, int);
 };
 
 IMPLEMENT_TRANSLATOR_LISTENER (Fingering_engraver, fingering);
 void
 Fingering_engraver::listen_fingering (Stream_event *ev)
 {
   events_.push_back (ev);
 }
 
 void
 Fingering_engraver::acknowledge_stem (Grob_info inf)
 {
   for (vsize i = 0; i < fingerings_.size (); i++)
     Side_position_interface::add_support (fingerings_[i], inf.grob ());
 }
 
 void
+Fingering_engraver::acknowledge_flag (Grob_info inf)
+{
+  for (vsize i = 0; i < fingerings_.size (); i++)
+    Side_position_interface::add_support (fingerings_[i], inf.grob ());
+}
+
+void
 Fingering_engraver::acknowledge_rhythmic_head (Grob_info inf)
 {
   for (vsize i = 0; i < fingerings_.size (); i++)
     {
       Grob *t = fingerings_[i];
       Side_position_interface::add_support (t, inf.grob ());
       if (!t->get_parent (X_AXIS))
         t->set_parent (inf.grob (), X_AXIS);
     }
 }
@@ skipping 58 matching lines @@
   fingerings_.clear ();
   events_.clear ();
 }
 
 Fingering_engraver::Fingering_engraver ()
 {
 }
 
 ADD_ACKNOWLEDGER (Fingering_engraver, rhythmic_head);
 ADD_ACKNOWLEDGER (Fingering_engraver, stem);
+ADD_ACKNOWLEDGER (Fingering_engraver, flag);
 
 ADD_TRANSLATOR (Fingering_engraver,
                 /* doc */
                 "Create fingering scripts.",
 
                 /* create */
                 "Fingering ",
 
                 /* read */
                 "",
 
                 /* write */
                 ""
                );