source: NonGTP/Boost/boost/serialization/optional.hpp @ 857

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// (C) Copyright 2002-4 Pavel Vozenilek . 
// 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)

// Provides non-intrusive serialization for boost::optional.

#ifndef BOOST_SERIALIZATION_OPTIONAL_HPP_
#define BOOST_SERIALIZATION_OPTIONAL_HPP_

#if defined(_MSC_VER) && (_MSC_VER >= 1020)
# pragma once
#endif

#include <boost/config.hpp>

#include <boost/optional.hpp>
#include <boost/serialization/split_free.hpp>
#include <boost/serialization/level.hpp>
#include <boost/serialization/nvp.hpp>
#include <boost/serialization/detail/stack_constructor.hpp>

// function specializations must be defined in the appropriate
// namespace - boost::serialization
namespace boost { 
namespace serialization {

template<class Archive, class T>
void save(
    Archive & ar, 
    const boost::optional<T> & t, 
    const unsigned int /*version*/
){
    const bool tflag = t;
    ar << boost::serialization::make_nvp("initialized", tflag);
    if (tflag)
        ar << boost::serialization::make_nvp("value", *t);
}

template<class Archive, class T>
void load(
    Archive & ar, 
    boost::optional<T> & t, 
    const unsigned int /*version*/
){
    bool tflag;
    ar >> boost::serialization::make_nvp("initialized", tflag);
    if (tflag){
        detail::stack_construct<Archive, T> aux(ar);
        ar >> boost::serialization::make_nvp("value", aux.reference());
        t.reset(aux.reference());
    }
    else {
        t.reset();
    }
}

template<class Archive, class T>
void serialize(
    Archive & ar, 
    boost::optional<T> & t, 
    const unsigned int version
){
    boost::serialization::split_free(ar, t, version);
}

// the following would be slightly more efficient.  But it
// would mean that archives created with programs that support
// TPS wouldn't be readable by programs that don't support TPS.
// Hence we decline to support this otherwise convenient optimization.
//#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
#if 0

template <class T>
struct implementation_level<optional<T> >
{
    typedef mpl::integral_c_tag tag;
    typedef mpl::int_<boost::serialization::object_serializable> type;
    BOOST_STATIC_CONSTANT(
        int , 
        value = boost::serialization::implementation_level::type::value
    );
};

template<class T>
struct tracking_level<optional<T> >
{
    typedef mpl::integral_c_tag tag;
    typedef mpl::int_<boost::serialization::track_never> type;
    BOOST_STATIC_CONSTANT(
        int , 
        value = boost::serialization::tracking_level::type::value
    );
};

#endif

} // serialization
} // namespace boost

#endif // BOOST_SERIALIZATION_OPTIONAL_HPP_