//-----------------------------------------------------------------------------// boost variant/detail/move.hpp header file// See http://www.boost.org for updates, documentation, and revision history.//-----------------------------------------------------------------------------////  Copyright (c) 2002-2003 Eric Friedman//  Copyright (c) 2002 by Andrei Alexandrescu////  Use, modification and distribution are 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)////  This file derivative of MoJO. Much thanks to Andrei for his initial work.//  See <http://www.cuj.com/experts/2102/alexandr.htm> for information on MOJO.//  Re-issued here under the Boost Software License, with permission of the original//  author (Andrei Alexandrescu).#ifndef BOOST_VARIANT_DETAIL_MOVE_HPP#define BOOST_VARIANT_DETAIL_MOVE_HPP#include <iterator> // for iterator_traits#include <new> // for placement new#include "boost/config.hpp"#include "boost/detail/workaround.hpp"#include "boost/mpl/if.hpp"#include "boost/type_traits/is_base_and_derived.hpp"namespace boost {namespace detail { namespace variant {//////////////////////////////////////////////////////////////////////////// forward declares//// NOTE: Incomplete until (if?) Boost.Move becomes part of Boost.//template <typename Deriving> class moveable;template <typename T>        class move_source;template <typename T>        class move_return;namespace detail {// (detail) moveable_tag//// Concrete type from which moveable<T> derives.//// TODO: Move into moveable_fwd.hpp and define has_move_constructor.//template <typename Deriving>struct moveable_tag{};} // namespace detail//////////////////////////////////////////////////////////////////////////// function template move//// Takes a T& and returns, if T derives moveable<T>, a move_source<T> for// the object; else, returns the T&.//namespace detail {// (detail) class template move_type//// Metafunction that, given moveable T, provides move_source<T>, else T&.//template <typename T>struct move_type{public: // metafunction result    typedef typename mpl::if_<          is_base_and_derived<detail::moveable_tag<T>, T>        , move_source<T>        , T&        >::type type;};} // namespace detailtemplate <typename T>inline    typename detail::move_type<T>::typemove(T& source){    typedef typename detail::move_type<T>::type        move_t;    return move_t(source);}//////////////////////////////////////////////////////////////////////////// class template return_t//// Metafunction that, given moveable T, provides move_return<T>, else T.//template <typename T>struct return_t{public: // metafunction result    typedef typename mpl::if_<          is_base_and_derived<moveable<T>, T>        , move_return<T>        , T        >::type type;};//////////////////////////////////////////////////////////////////////////// function template move_swap//// Swaps using Koenig lookup but falls back to move-swap for primitive// types and on non-conforming compilers.//#if   defined(BOOST_NO_ARGUMENT_DEPENDENT_LOOKUP)   \ ||   BOOST_WORKAROUND(__GNUC__, BOOST_TESTED_AT(2))// [Indicate that move_swap by overload is disabled...]#define BOOST_NO_MOVE_SWAP_BY_OVERLOAD// [...and provide straight swap-by-move implementation:]template <typename T>inline void move_swap(T& lhs, T& rhs){    T tmp( boost::detail::variant::move(lhs) );    lhs = boost::detail::variant::move(rhs);    rhs = boost::detail::variant::move(tmp);}#else// !workaroundnamespace detail { namespace move_swap {template <typename T>inline void swap(T& lhs, T& rhs){    T tmp( boost::detail::variant::move(lhs) );    lhs = boost::detail::variant::move(rhs);    rhs = boost::detail::variant::move(tmp);}}} // namespace detail::move_swaptemplate <typename T>inline void move_swap(T& lhs, T& rhs){    using detail::move_swap::swap;    swap(lhs, rhs);}#endif // workaround}} // namespace detail::variant} // namespace boost#endif // BOOST_VARIANT_DETAIL_MOVE_HPP