//----------------------------------------------------------------------------- | |
// 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 detail | |
template <typename T> | |
inline | |
typename detail::move_type<T>::type | |
move(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// !workaround | |
namespace 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_swap | |
template <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 | |