| #ifndef BOOST_SERIALIZATION_STATE_SAVER_HPP |
| #define BOOST_SERIALIZATION_STATE_SAVER_HPP |
| |
| // MS compatible compilers support #pragma once |
| #if defined(_MSC_VER) && (_MSC_VER >= 1020) |
| # pragma once |
| #endif |
| |
| /////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8 |
| // state_saver.hpp: |
| |
| // (C) Copyright 2003-4 Pavel Vozenilek and Robert Ramey - http://www.rrsd.com. |
| // Use, modification and distribution is subject to 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) |
| |
| // See http://www.boost.org/libs/serialization for updates, documentation, and revision history. |
| |
| // Inspired by Daryle Walker's iostate_saver concept. This saves the original |
| // value of a variable when a state_saver is constructed and restores |
| // upon destruction. Useful for being sure that state is restored to |
| // variables upon exit from scope. |
| |
| |
| #include <boost/config.hpp> |
| #ifndef BOOST_NO_EXCEPTIONS |
| #include <exception> |
| #endif |
| |
| #include <boost/call_traits.hpp> |
| #include <boost/noncopyable.hpp> |
| #include <boost/type_traits/has_nothrow_copy.hpp> |
| #include <boost/detail/no_exceptions_support.hpp> |
| |
| #include <boost/mpl/eval_if.hpp> |
| #include <boost/mpl/identity.hpp> |
| |
| namespace boost { |
| namespace serialization { |
| |
| template<class T> |
| // T requirements: |
| // - POD or object semantic (cannot be reference, function, ...) |
| // - copy constructor |
| // - operator = (no-throw one preferred) |
| class state_saver : private boost::noncopyable |
| { |
| private: |
| const T previous_value; |
| T & previous_ref; |
| |
| struct restore { |
| static void invoke(T & previous_ref, const T & previous_value){ |
| previous_ref = previous_value; // won't throw |
| } |
| }; |
| |
| struct restore_with_exception { |
| static void invoke(T & previous_ref, const T & previous_value){ |
| BOOST_TRY{ |
| previous_ref = previous_value; |
| } |
| BOOST_CATCH(::std::exception &) { |
| // we must ignore it - we are in destructor |
| } |
| BOOST_CATCH_END |
| } |
| }; |
| |
| public: |
| state_saver( |
| T & object |
| ) : |
| previous_value(object), |
| previous_ref(object) |
| {} |
| |
| ~state_saver() { |
| #ifndef BOOST_NO_EXCEPTIONS |
| typedef BOOST_DEDUCED_TYPENAME mpl::eval_if< |
| has_nothrow_copy< T >, |
| mpl::identity<restore>, |
| mpl::identity<restore_with_exception> |
| >::type typex; |
| typex::invoke(previous_ref, previous_value); |
| #else |
| previous_ref = previous_value; |
| #endif |
| } |
| |
| }; // state_saver<> |
| |
| } // serialization |
| } // boost |
| |
| #endif //BOOST_SERIALIZATION_STATE_SAVER_HPP |