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diff --git a/libs/sigc++2/sigc++/reference_wrapper.h b/libs/sigc++2/sigc++/reference_wrapper.h
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+/*
+ * Copyright 2002, The libsigc++ Development Team
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2.1 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
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ */
+#ifndef _SIGC_REFERENCE_WRAPPER_H_
+#define _SIGC_REFERENCE_WRAPPER_H_
+
+namespace sigc {
+
+/** Reference wrapper.
+ * Use sigc::ref() to create a reference wrapper.
+ */
+template <class T_type>
+struct reference_wrapper
+{
+  explicit reference_wrapper(T_type& v)
+    : value_(v)  {}
+
+  operator T_type& () const
+    { return value_; }
+
+  T_type& value_;
+};
+
+/** Const reference wrapper.
+ * Use sigc::ref() to create a const reference wrapper.
+ */
+template <class T_type>
+struct const_reference_wrapper
+{
+  explicit const_reference_wrapper(const T_type& v)
+    : value_(v)  {}
+
+  operator const T_type& () const
+    { return value_; }
+
+  const T_type& value_;
+};
+
+/** Creates a reference wrapper.
+ * Passing an object throught sigc::ref() makes libsigc++ adaptors
+ * like, e.g., sigc::bind store references to the object instead of copies.
+ * If the object type inherits from sigc::trackable this will ensure
+ * automatic invalidation of the adaptors when the object is deleted
+ * or overwritten.
+ *
+ * @param v Reference to store.
+ * @return A reference wrapper.
+ */
+template <class T_type>
+reference_wrapper<T_type> ref(T_type& v)
+{ return reference_wrapper<T_type>(v); }
+
+/** Creates a const reference wrapper.
+ * Passing an object throught sigc::ref() makes libsigc++ adaptors
+ * like, e.g., sigc::bind store references to the object instead of copies.
+ * If the object type inherits from sigc::trackable this will ensure
+ * automatic invalidation of the adaptors when the object is deleted
+ * or overwritten.
+ *
+ * @param v Reference to store.
+ * @return A reference wrapper.
+ */
+template <class T_type>
+const_reference_wrapper<T_type> ref(const T_type& v)
+{ return const_reference_wrapper<T_type>(v); }
+
+template <class T_type>
+struct unwrap_reference
+{
+  typedef T_type type;
+};
+
+template <class T_type>
+struct unwrap_reference<reference_wrapper<T_type> >
+{
+  typedef T_type& type;
+};
+
+template <class T_type>
+struct unwrap_reference<const_reference_wrapper<T_type> >
+{
+  typedef const T_type& type;
+};
+
+template <class T_type>
+T_type& unwrap(T_type& v)
+{ return v; }
+
+template <class T_type>
+const T_type& unwrap(const T_type& v)
+{ return v; }
+
+template <class T_type>
+T_type& unwrap(const reference_wrapper<T_type>& v)
+{ return v; }
+
+template <class T_type>
+const T_type& unwrap(const const_reference_wrapper<T_type>& v)
+{ return v; }
+
+} /* namespace sigc */
+
+#endif /* _SIGC_REFERENCE_WRAPPER_H_ */