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96 lines
2.7 KiB
96 lines
2.7 KiB
#ifndef BOOST_SERIALIZATION_STATE_SAVER_HPP |
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#define BOOST_SERIALIZATION_STATE_SAVER_HPP |
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// MS compatible compilers support #pragma once |
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#if defined(_MSC_VER) && (_MSC_VER >= 1020) |
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# pragma once |
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#endif |
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/////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8 |
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// state_saver.hpp: |
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// (C) Copyright 2003-4 Pavel Vozenilek and Robert Ramey - http://www.rrsd.com. |
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// Use, modification and distribution is subject to the Boost Software |
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// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at |
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// http://www.boost.org/LICENSE_1_0.txt) |
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// See http://www.boost.org/libs/serialization for updates, documentation, and revision history. |
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// Inspired by Daryle Walker's iostate_saver concept. This saves the original |
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// value of a variable when a state_saver is constructed and restores |
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// upon destruction. Useful for being sure that state is restored to |
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// variables upon exit from scope. |
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#include <boost/config.hpp> |
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#ifndef BOOST_NO_EXCEPTIONS |
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#include <exception> |
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#endif |
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#include <boost/call_traits.hpp> |
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#include <boost/noncopyable.hpp> |
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#include <boost/type_traits/has_nothrow_copy.hpp> |
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#include <boost/detail/no_exceptions_support.hpp> |
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#include <boost/mpl/eval_if.hpp> |
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#include <boost/mpl/identity.hpp> |
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namespace boost { |
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namespace serialization { |
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template<class T> |
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// T requirements: |
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// - POD or object semantic (cannot be reference, function, ...) |
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// - copy constructor |
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// - operator = (no-throw one preferred) |
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class state_saver : private boost::noncopyable |
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{ |
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private: |
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const T previous_value; |
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T & previous_ref; |
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struct restore { |
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static void invoke(T & previous_ref, const T & previous_value){ |
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previous_ref = previous_value; // won't throw |
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} |
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}; |
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struct restore_with_exception { |
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static void invoke(T & previous_ref, const T & previous_value){ |
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BOOST_TRY{ |
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previous_ref = previous_value; |
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} |
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BOOST_CATCH(::std::exception &) { |
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// we must ignore it - we are in destructor |
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} |
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BOOST_CATCH_END |
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} |
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}; |
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public: |
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state_saver( |
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T & object |
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) : |
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previous_value(object), |
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previous_ref(object) |
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{} |
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~state_saver() { |
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#ifndef BOOST_NO_EXCEPTIONS |
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typedef BOOST_DEDUCED_TYPENAME mpl::eval_if< |
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has_nothrow_copy< T >, |
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mpl::identity<restore>, |
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mpl::identity<restore_with_exception> |
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>::type typex; |
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typex::invoke(previous_ref, previous_value); |
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#else |
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previous_ref = previous_value; |
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#endif |
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} |
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}; // state_saver<> |
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} // serialization |
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} // boost |
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#endif //BOOST_SERIALIZATION_STATE_SAVER_HPP
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