Doc-es: various updates.

[lilypond.git] / lily / stencil-expression.cc

diff --git a/lily/stencil-expression.cc b/lily/stencil-expression.cc
index ea9c08871979a16620974b071798210c0b6c63b3..8d804196202368c1eaf1043cac78de4e91253fb2 100644 (file)
--- a/lily/stencil-expression.cc
+++ b/lily/stencil-expression.cc
@@ -1,35 +1,41 @@
 /*
-  stencil-expression.cc -- keep track of which expressions are valid
-  stencil exps.
+  This file is part of LilyPond, the GNU music typesetter.
 
-  source file of the GNU LilyPond music typesetter
+  Copyright (C) 2005--2015 Han-Wen Nienhuys <hanwen@xs4all.nl>
 
-  (c) 2005--2008 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 "stencil.hh"
+#include "protected-scm.hh"
 
-static SCM heads;
+static Protected_scm heads (SCM_EOL);
 
 void register_stencil_head (SCM symbol)
 {
-  if (!heads)
-    heads = scm_permanent_object (scm_cons (SCM_EOL, SCM_EOL));
-  
   scm_set_object_property_x (symbol, ly_symbol2scm ("stencil-head?"), SCM_BOOL_T);
-  scm_set_cdr_x (heads,  scm_cons (symbol, scm_cdr (heads)));
+  heads = scm_cons (symbol, heads);
 }
 
 bool
 is_stencil_head (SCM symbol)
 {
-  return scm_object_property (symbol, ly_symbol2scm ("stencil-head?"))
-    == SCM_BOOL_T;
+  return to_boolean (scm_object_property (symbol, ly_symbol2scm ("stencil-head?")));
 }
 
 SCM
 all_stencil_heads ()
 {
-  return scm_cdr (heads);
+  return heads;
 }
-