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