97 lines
2.8 KiB
C++
97 lines
2.8 KiB
C++
#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
|