release: 1.5.29

[lilypond.git] / lily / include / sequential-music-iterator.hh

diff --git a/lily/include/sequential-music-iterator.hh b/lily/include/sequential-music-iterator.hh
index 963faf2d07e0508badc5900df1c92b2e8252bef2..62a251e22f4dc278abac992628be283dce8174c1 100644 (file)
--- a/lily/include/sequential-music-iterator.hh
+++ b/lily/include/sequential-music-iterator.hh
@@ -3,7 +3,7 @@
 
   source file of the GNU LilyPond music typesetter
 
-  (c)  1997--2001 Han-Wen Nienhuys <hanwen@cs.uu.nl>
+  (c)  1997--2002 Han-Wen Nienhuys <hanwen@cs.uu.nl>
 */
 
 #ifndef SEQUENTIAL_MUSIC_ITERATOR_HH
@@ -11,6 +11,39 @@
 
 #include "music-iterator.hh"
 
+
+/*
+
+  This is a lookahead list for grace notes.
+
+   {  ... X \grace Y  Z ... }
+
+   normally, the ending of X is the start of Z. In case of a grace
+   note, we take off a little at the end of X. What is stored: START
+   (start point of X), LENGTH (length of X), GRACE_START (start_music
+   of Y), and the next fixup element.
+
+  This is also done for nested musics, i.e.
+
+  voiceA = \notes { \grace b16 c'2 }
+  voiceB = \notes { c'2 \voiceA }
+
+  the iterator for voiceB will contain a fixup entry with (START=0/1,
+  LENGTH=2/1, GRACE_START=(0G-1/16) ) 
+   
+  Graces at the start of a sequential music iterator are handled
+  by initting here_mom_ with Music::start_music (); no fixups are needed.
+
+*/
+struct Grace_fixup 
+{
+  Moment start_;
+  Moment length_;
+
+  Rational grace_start_;  
+  Grace_fixup *next_;
+};
+
 /** Sequential_music iteration: walk each element in turn, and
   construct an iterator for every element.
   
@@ -18,6 +51,8 @@
 class Sequential_music_iterator :  public Music_iterator
 {
 public:
+  Grace_fixup * grace_fixups_;
+  
   VIRTUAL_COPY_CONS (Music_iterator);
   static SCM constructor_cxx_function;
   Sequential_music_iterator ();