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