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--- /dev/null
+++ b/src/Stack.h
@@ -0,0 +1,50 @@
+// This may look like C code, but it is really -*- C++ -*-
+/* 
+Copyright (C) 1988 Free Software Foundation
+    written by Doug Lea (dl@rocky.oswego.edu)
+
+This file is part of the GNU C++ Library.  This library is free
+software; you can redistribute it and/or modify it under the terms of
+the GNU Library General Public License as published by the Free
+Software Foundation; either version 2 of the License, or (at your
+option) any later version.  This library 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 Library General Public License for more details.
+You should have received a copy of the GNU Library General Public
+License along with this library; if not, write to the Free Software
+Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+
+#ifndef _Stack_h
+#ifdef __GNUG__
+//#pragma interface
+#endif
+#define _Stack_h 1
+
+template <class T>
+class Stack
+{
+ public:
+  Stack (void) { }
+  virtual ~Stack (void) { }
+
+  virtual void push (const T& item) = 0;
+
+  virtual T pop (void) = 0;
+  virtual T& top (void) = 0; 
+
+  virtual void del_top (void) = 0;
+
+  virtual int empty (void) = 0;
+  virtual int full (void) = 0;
+  virtual int length (void) = 0;
+
+  virtual void clear (void) = 0;
+
+  void error (const char *msg);
+  virtual int OK (void) = 0;
+};
+
+#endif