Add basic scheme programmable engravers.

[lilypond.git] / lily / engraver.cc

diff --git a/lily/engraver.cc b/lily/engraver.cc
index 1b83b07a85ce638cab4ff0c448318779c01dbde5..9e6b23118cecef61641807e6b18c6b2312f1b894 100644 (file)
--- a/lily/engraver.cc
+++ b/lily/engraver.cc
@@ -70,9 +70,8 @@ Engraver::announce_grob (Grob *e, SCM cause)
 
 
 /*
-  CAUSE is the object (typically a Music object)  that
-  was the reason for making E.
-*/
+  CAUSE is the object (typically a grob or stream-event object) that
+  was the reason for ending E.  */
 void
 Engraver::announce_end_grob (Grob *e, SCM cause)
 {
@@ -175,13 +174,26 @@ Engraver::internal_make_column (SCM x, char const *name,
 }
 
 Spanner *
-Engraver::internal_make_spanner (SCM x, SCM cause, char const *name, char const *file, int line, char const *fun)
+Engraver::internal_make_spanner (SCM x, SCM cause, char const *name,
+                                char const *file, int line, char const *fun)
 {
   Spanner *sp = dynamic_cast<Spanner *> (internal_make_grob (x, cause, name, file, line, fun));
   assert (sp);
   return sp;
 }
 
+Engraver*
+unsmob_engraver (SCM eng)
+{
+  return dynamic_cast<Engraver*> (unsmob_translator (eng));
+}
+
+bool
+ly_is_grob_cause (SCM obj)
+{
+  return unsmob_grob (obj) || unsmob_stream_event (obj);
+}
+
 #include "translator.icc"
 
 ADD_TRANSLATOR (Engraver,
@@ -198,3 +210,4 @@ ADD_TRANSLATOR (Engraver,
                ""
                );
 
+