williamr@2: //-----------------------------------------------------------------------------
williamr@2: // boost variant/detail/move.hpp header file
williamr@2: // See http://www.boost.org for updates, documentation, and revision history.
williamr@2: //-----------------------------------------------------------------------------
williamr@2: //
williamr@2: //  Copyright (c) 2002-2003 Eric Friedman
williamr@2: //  Copyright (c) 2002 by Andrei Alexandrescu
williamr@2: //
williamr@2: //  Use, modification and distribution are subject to the
williamr@2: //  Boost Software License, Version 1.0. (See accompanying file
williamr@2: //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
williamr@2: //
williamr@2: //  This file derivative of MoJO. Much thanks to Andrei for his initial work.
williamr@2: //  See <http://www.cuj.com/experts/2102/alexandr.htm> for information on MOJO.
williamr@2: //  Re-issued here under the Boost Software License, with permission of the original
williamr@2: //  author (Andrei Alexandrescu).
williamr@2: 
williamr@2: 
williamr@2: #ifndef BOOST_VARIANT_DETAIL_MOVE_HPP
williamr@2: #define BOOST_VARIANT_DETAIL_MOVE_HPP
williamr@2: 
williamr@2: #include <iterator> // for iterator_traits
williamr@2: #include <new> // for placement new
williamr@2: 
williamr@2: #include "boost/config.hpp"
williamr@2: #include "boost/detail/workaround.hpp"
williamr@2: #include "boost/mpl/if.hpp"
williamr@2: #include "boost/type_traits/is_base_and_derived.hpp"
williamr@2: 
williamr@2: namespace boost {
williamr@2: namespace detail { namespace variant {
williamr@2: 
williamr@2: //////////////////////////////////////////////////////////////////////////
williamr@2: // forward declares
williamr@2: //
williamr@2: // NOTE: Incomplete until (if?) Boost.Move becomes part of Boost.
williamr@2: //
williamr@2: template <typename Deriving> class moveable;
williamr@2: template <typename T>        class move_source;
williamr@2: template <typename T>        class move_return;
williamr@2: 
williamr@2: namespace detail {
williamr@2: 
williamr@2: // (detail) moveable_tag
williamr@2: //
williamr@2: // Concrete type from which moveable<T> derives.
williamr@2: //
williamr@2: // TODO: Move into moveable_fwd.hpp and define has_move_constructor.
williamr@2: //
williamr@2: template <typename Deriving>
williamr@2: struct moveable_tag
williamr@2: {
williamr@2: };
williamr@2: 
williamr@2: } // namespace detail
williamr@2: 
williamr@2: //////////////////////////////////////////////////////////////////////////
williamr@2: // function template move
williamr@2: //
williamr@2: // Takes a T& and returns, if T derives moveable<T>, a move_source<T> for
williamr@2: // the object; else, returns the T&.
williamr@2: //
williamr@2: 
williamr@2: namespace detail {
williamr@2: 
williamr@2: // (detail) class template move_type
williamr@2: //
williamr@2: // Metafunction that, given moveable T, provides move_source<T>, else T&.
williamr@2: //
williamr@2: template <typename T>
williamr@2: struct move_type
williamr@2: {
williamr@2: public: // metafunction result
williamr@2: 
williamr@2:     typedef typename mpl::if_<
williamr@2:           is_base_and_derived<detail::moveable_tag<T>, T>
williamr@2:         , move_source<T>
williamr@2:         , T&
williamr@2:         >::type type;
williamr@2: 
williamr@2: };
williamr@2: 
williamr@2: } // namespace detail
williamr@2: 
williamr@2: template <typename T>
williamr@2: inline
williamr@2:     typename detail::move_type<T>::type
williamr@2: move(T& source)
williamr@2: {
williamr@2:     typedef typename detail::move_type<T>::type
williamr@2:         move_t;
williamr@2: 
williamr@2:     return move_t(source);
williamr@2: }
williamr@2: 
williamr@2: //////////////////////////////////////////////////////////////////////////
williamr@2: // class template return_t
williamr@2: //
williamr@2: // Metafunction that, given moveable T, provides move_return<T>, else T.
williamr@2: //
williamr@2: template <typename T>
williamr@2: struct return_t
williamr@2: {
williamr@2: public: // metafunction result
williamr@2: 
williamr@2:     typedef typename mpl::if_<
williamr@2:           is_base_and_derived<moveable<T>, T>
williamr@2:         , move_return<T>
williamr@2:         , T
williamr@2:         >::type type;
williamr@2: 
williamr@2: };
williamr@2: 
williamr@2: //////////////////////////////////////////////////////////////////////////
williamr@2: // function template move_swap
williamr@2: //
williamr@2: // Swaps using Koenig lookup but falls back to move-swap for primitive
williamr@2: // types and on non-conforming compilers.
williamr@2: //
williamr@2: 
williamr@2: #if   defined(BOOST_NO_ARGUMENT_DEPENDENT_LOOKUP)   \
williamr@2:  ||   BOOST_WORKAROUND(__GNUC__, BOOST_TESTED_AT(2))
williamr@2: 
williamr@2: // [Indicate that move_swap by overload is disabled...]
williamr@2: #define BOOST_NO_MOVE_SWAP_BY_OVERLOAD
williamr@2: 
williamr@2: // [...and provide straight swap-by-move implementation:]
williamr@2: template <typename T>
williamr@2: inline void move_swap(T& lhs, T& rhs)
williamr@2: {
williamr@2:     T tmp( boost::detail::variant::move(lhs) );
williamr@2:     lhs = boost::detail::variant::move(rhs);
williamr@2:     rhs = boost::detail::variant::move(tmp);
williamr@2: }
williamr@2: 
williamr@2: #else// !workaround
williamr@2: 
williamr@2: namespace detail { namespace move_swap {
williamr@2: 
williamr@2: template <typename T>
williamr@2: inline void swap(T& lhs, T& rhs)
williamr@2: {
williamr@2:     T tmp( boost::detail::variant::move(lhs) );
williamr@2:     lhs = boost::detail::variant::move(rhs);
williamr@2:     rhs = boost::detail::variant::move(tmp);
williamr@2: }
williamr@2: 
williamr@2: }} // namespace detail::move_swap
williamr@2: 
williamr@2: template <typename T>
williamr@2: inline void move_swap(T& lhs, T& rhs)
williamr@2: {
williamr@2:     using detail::move_swap::swap;
williamr@2: 
williamr@2:     swap(lhs, rhs);
williamr@2: }
williamr@2: 
williamr@2: #endif // workaround
williamr@2: 
williamr@2: }} // namespace detail::variant
williamr@2: } // namespace boost
williamr@2: 
williamr@2: #endif // BOOST_VARIANT_DETAIL_MOVE_HPP
williamr@2: 
williamr@2: 
williamr@2: