add new file

git-svn-id: svn://localhost/ardour2/branches/3.0@6727 d708f5d6-7413-0410-9779-e7cbd77b26cf

libs/pbd/pbd/stateful_owner.h

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+/*
+    Copyright (C) 2000-2010 Paul Davis 
+
+    This program 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 2 of the License, or
+    (at your option) any later version.
+
+    This program 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 this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+#ifndef __pbd_stateful_owner_h__
+#define __pbd_stateful_owner_h__
+
+#include <vector>
+
+namespace PBD {
+
+class StatefulDiffCommand;
+
+/** Base (pure virtual) class for objects with other Stateful's within */
+class StatefulOwner {
+  public:
+	StatefulOwner () {}
+	virtual ~StatefulOwner () {}
+
+        virtual void rdiff (std::vector<StatefulDiffCommand*>& cmds) const = 0;
+        virtual void clear_owned_history () = 0;
+};
+
+} // namespace PBD
+
+#endif /* __pbd_stateful_owner_h__ */
+