Added boost header

test/external/boost/xpressive/detail/utility/save_restore.hpp

@@ -0,0 +1,55 @@
+///////////////////////////////////////////////////////////////////////////////
+// save_restore.hpp
+//
+//  Copyright 2008 Eric Niebler. Distributed under the Boost
+//  Software License, Version 1.0. (See accompanying file
+//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_XPRESSIVE_DETAIL_UTILITY_SAVE_RESTORE_HPP_EAN_10_04_2005
+#define BOOST_XPRESSIVE_DETAIL_UTILITY_SAVE_RESTORE_HPP_EAN_10_04_2005
+
+// MS compatible compilers support #pragma once
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
+#endif
+
+#include <boost/noncopyable.hpp>
+
+namespace boost { namespace xpressive { namespace detail
+{
+
+    template<typename T>
+    struct save_restore
+      : private noncopyable
+    {
+        explicit save_restore(T &t)
+          : ref(t)
+          , val(t)
+        {
+        }
+
+        save_restore(T &t, T const &n)
+          : ref(t)
+          , val(t)
+        {
+            this->ref = n;
+        }
+
+        ~save_restore()
+        {
+            this->ref = this->val;
+        }
+
+        void restore()
+        {
+            this->ref = this->val;
+        }
+
+    private:
+        T &ref;
+        T const val;
+    };
+
+}}}
+
+#endif