/Src/Dependencies/Boost/boost/variant/detail/move.hpp

  1//-----------------------------------------------------------------------------
  2// boost variant/detail/move.hpp header file
  3// See http://www.boost.org for updates, documentation, and revision history.
  4//-----------------------------------------------------------------------------
  5//
  6//  Copyright (c) 2002-2003 Eric Friedman
  7//  Copyright (c) 2002 by Andrei Alexandrescu
  8//
  9//  Use, modification and distribution are subject to the
 10//  Boost Software License, Version 1.0. (See accompanying file
 11//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 12//
 13//  This file derivative of MoJO. Much thanks to Andrei for his initial work.
 14//  See <http://www.cuj.com/experts/2102/alexandr.htm> for information on MOJO.
 15//  Re-issued here under the Boost Software License, with permission of the original
 16//  author (Andrei Alexandrescu).
 17
 18
 19#ifndef BOOST_VARIANT_DETAIL_MOVE_HPP
 20#define BOOST_VARIANT_DETAIL_MOVE_HPP
 21
 22#include <iterator> // for iterator_traits
 23#include <new> // for placement new
 24
 25#include "boost/config.hpp"
 26#include "boost/detail/workaround.hpp"
 27#include "boost/mpl/if.hpp"
 28#include "boost/type_traits/is_base_and_derived.hpp"
 29
 30namespace boost {
 31namespace detail { namespace variant {
 32
 33//////////////////////////////////////////////////////////////////////////
 34// forward declares
 35//
 36// NOTE: Incomplete until (if?) Boost.Move becomes part of Boost.
 37//
 38template <typename Deriving> class moveable;
 39template <typename T>        class move_source;
 40template <typename T>        class move_return;
 41
 42namespace detail {
 43
 44// (detail) moveable_tag
 45//
 46// Concrete type from which moveable<T> derives.
 47//
 48// TODO: Move into moveable_fwd.hpp and define has_move_constructor.
 49//
 50template <typename Deriving>
 51struct moveable_tag
 52{
 53};
 54
 55} // namespace detail
 56
 57//////////////////////////////////////////////////////////////////////////
 58// function template move
 59//
 60// Takes a T& and returns, if T derives moveable<T>, a move_source<T> for
 61// the object; else, returns the T&.
 62//
 63
 64namespace detail {
 65
 66// (detail) class template move_type
 67//
 68// Metafunction that, given moveable T, provides move_source<T>, else T&.
 69//
 70template <typename T>
 71struct move_type
 72{
 73public: // metafunction result
 74
 75    typedef typename mpl::if_<
 76          is_base_and_derived<detail::moveable_tag<T>, T>
 77        , move_source<T>
 78        , T&
 79        >::type type;
 80
 81};
 82
 83} // namespace detail
 84
 85template <typename T>
 86inline
 87    typename detail::move_type<T>::type
 88move(T& source)
 89{
 90    typedef typename detail::move_type<T>::type
 91        move_t;
 92
 93    return move_t(source);
 94}
 95
 96//////////////////////////////////////////////////////////////////////////
 97// class template return_t
 98//
 99// Metafunction that, given moveable T, provides move_return<T>, else T.
100//
101template <typename T>
102struct return_t
103{
104public: // metafunction result
105
106    typedef typename mpl::if_<
107          is_base_and_derived<moveable<T>, T>
108        , move_return<T>
109        , T
110        >::type type;
111
112};
113
114//////////////////////////////////////////////////////////////////////////
115// function template move_swap
116//
117// Swaps using Koenig lookup but falls back to move-swap for primitive
118// types and on non-conforming compilers.
119//
120
121#if   defined(BOOST_NO_ARGUMENT_DEPENDENT_LOOKUP)   \
122 ||   BOOST_WORKAROUND(__GNUC__, BOOST_TESTED_AT(2))
123
124// [Indicate that move_swap by overload is disabled...]
125#define BOOST_NO_MOVE_SWAP_BY_OVERLOAD
126
127// [...and provide straight swap-by-move implementation:]
128template <typename T>
129inline void move_swap(T& lhs, T& rhs)
130{
131    T tmp( boost::detail::variant::move(lhs) );
132    lhs = boost::detail::variant::move(rhs);
133    rhs = boost::detail::variant::move(tmp);
134}
135
136#else// !workaround
137
138namespace detail { namespace move_swap {
139
140template <typename T>
141inline void swap(T& lhs, T& rhs)
142{
143    T tmp( boost::detail::variant::move(lhs) );
144    lhs = boost::detail::variant::move(rhs);
145    rhs = boost::detail::variant::move(tmp);
146}
147
148}} // namespace detail::move_swap
149
150template <typename T>
151inline void move_swap(T& lhs, T& rhs)
152{
153    using detail::move_swap::swap;
154
155    swap(lhs, rhs);
156}
157
158#endif // workaround
159
160}} // namespace detail::variant
161} // namespace boost
162
163#endif // BOOST_VARIANT_DETAIL_MOVE_HPP
164
165
166