detail/utility/save_restore.hpp

0001 ///////////////////////////////////////////////////////////////////////////////
0002 // save_restore.hpp
0003 //
0004 //  Copyright 2008 Eric Niebler. Distributed under the Boost
0005 //  Software License, Version 1.0. (See accompanying file
0006 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0007
0008 #ifndef BOOST_XPRESSIVE_DETAIL_UTILITY_SAVE_RESTORE_HPP_EAN_10_04_2005
0009 #define BOOST_XPRESSIVE_DETAIL_UTILITY_SAVE_RESTORE_HPP_EAN_10_04_2005
0010
0011 // MS compatible compilers support #pragma once
0012 #if defined(_MSC_VER)
0013 # pragma once
0014 #endif
0015
0016 #include <boost/noncopyable.hpp>
0017
0018 namespace boost { namespace xpressive { namespace detail
0019 {
0020
0021     template<typename T>
0022     struct save_restore
0023       : private noncopyable
0024     {
0025         explicit save_restore(T &t)
0026           : ref(t)
0027           , val(t)
0028         {
0029         }
0030
0031         save_restore(T &t, T const &n)
0032           : ref(t)
0033           , val(t)
0034         {
0035             this->ref = n;
0036         }
0037
0038         ~save_restore()
0039         {
0040             this->ref = this->val;
0041         }
0042
0043         void restore()
0044         {
0045             this->ref = this->val;
0046         }
0047
0048     private:
0049         T &ref;
0050         T const val;
0051     };
0052
0053 }}}
0054
0055 #endif