Add basic scheme programmable engravers.

[lilypond.git] / lily / engraver-scheme.cc

diff --git a/lily/engraver-scheme.cc b/lily/engraver-scheme.cc
new file mode 100644 (file)
index 0000000..00fc5e1
--- /dev/null
+++ b/lily/engraver-scheme.cc
@@ -0,0 +1,40 @@
+/*
+  This file is part of LilyPond, the GNU music typesetter.
+
+  Copyright (C) 1997--2009 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.
+
+  LilyPond is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with LilyPond.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "engraver.hh"
+#include "grob.hh"
+
+LY_DEFINE (ly_engraver_make_grob, "ly:engraver-make-grob",
+          3, 0, 0, (SCM engraver, SCM grob_name, SCM cause),
+          "Creates a grob originating from given engraver instance, "
+          "with give @code{grob_name}, a symbol.  "
+          "@code{cause} should either be another grob "
+          "or a music event.")
+{
+  LY_ASSERT_TYPE (unsmob_engraver, engraver, 1);
+  LY_ASSERT_TYPE (ly_is_symbol, grob_name, 2);
+  LY_ASSERT_TYPE (ly_is_grob_cause, cause, 3);
+
+  Grob *g = unsmob_engraver (engraver)->
+    internal_make_grob(grob_name, cause,
+                      ly_symbol2string (grob_name).c_str (),
+                      "scheme", 0, "scheme");
+  return g->self_scm ();
+}
+