//----------------------------------------------------------------------------- // 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