| //----------------------------------------------------------------------------- |
| // 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 |
| |
| |
| |