Imported Upstream version 2.19.45

[lilypond.git] / lily / include / grob-properties.hh

diff --git a/lily/include/grob-properties.hh b/lily/include/grob-properties.hh
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+/*
+  This file is part of LilyPond, the GNU music typesetter.
+
+  Copyright (C) 2014--2015 David Kastrup <dak@gnu.org>
+
+  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/>.
+*/
+
+// This module is concerned with managing grob-properties (more
+// exactly, grob property templates, as they are not yet part of a
+// grob) inside of context properties, in a context-hierarchical
+// manner, with one stack for properties and subproperties per
+// context.
+
+#ifndef GROB_PROPERTIES_HH
+#define GROB_PROPERTIES_HH
+
+#include "lily-proto.hh"
+
+// Several algorithms on Grob_properties need self-identifying
+// information to work properly, but there is no point in storing them
+// in the Grob_properties data structure itself.  Instead we create a
+// reflective data structure containing all necessary information for
+// the algorithms processing Grob_properties.
+
+class Grob_property_info {
+  Context * const context_;
+  SCM const symbol_;
+  Grob_properties *props_;
+public:
+  Grob_property_info (Context *context, SCM symbol, Grob_properties *props = 0)
+    : context_ (context), symbol_ (symbol), props_ (props)
+  { }
+  operator bool () { return props_; }
+  Grob_property_info find ();
+  bool check ();
+  bool create ();
+  SCM updated ();
+  SCM push (SCM path, SCM value);
+  SCM temporary_override (SCM path, SCM value);
+  SCM temporary_revert (SCM path);
+  void matched_pop (SCM);
+  void pop (SCM path);
+  void pushpop (SCM path, SCM value)
+  {
+    if (SCM_UNBNDP (value))
+      return pop (path);
+    push (path, value);
+  }
+};
+#endif