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1 : // Move, forward and identity for C++11 + swap -*- C++ -*- 2 : 3 : // Copyright (C) 2007-2019 Free Software Foundation, Inc. 4 : // 5 : // This file is part of the GNU ISO C++ Library. This library is free 6 : // software; you can redistribute it and/or modify it under the 7 : // terms of the GNU General Public License as published by the 8 : // Free Software Foundation; either version 3, or (at your option) 9 : // any later version. 10 : 11 : // This library is distributed in the hope that it will be useful, 12 : // but WITHOUT ANY WARRANTY; without even the implied warranty of 13 : // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 : // GNU General Public License for more details. 15 : 16 : // Under Section 7 of GPL version 3, you are granted additional 17 : // permissions described in the GCC Runtime Library Exception, version 18 : // 3.1, as published by the Free Software Foundation. 19 : 20 : // You should have received a copy of the GNU General Public License and 21 : // a copy of the GCC Runtime Library Exception along with this program; 22 : // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 : // <http://www.gnu.org/licenses/>. 24 : 25 : /** @file bits/move.h 26 : * This is an internal header file, included by other library headers. 27 : * Do not attempt to use it directly. @headername{utility} 28 : */ 29 : 30 : #ifndef _MOVE_H 31 : #define _MOVE_H 1 32 : 33 : #include <bits/c++config.h> 34 : #include <bits/concept_check.h> 35 : 36 : namespace std _GLIBCXX_VISIBILITY(default) 37 : { 38 : _GLIBCXX_BEGIN_NAMESPACE_VERSION 39 : 40 : // Used, in C++03 mode too, by allocators, etc. 41 : /** 42 : * @brief Same as C++11 std::addressof 43 : * @ingroup utilities 44 : */ 45 : template<typename _Tp> 46 : inline _GLIBCXX_CONSTEXPR _Tp* 47 1711265065 : __addressof(_Tp& __r) _GLIBCXX_NOEXCEPT 48 : { return __builtin_addressof(__r); } 49 : 50 : #if __cplusplus >= 201103L 51 : 52 : _GLIBCXX_END_NAMESPACE_VERSION 53 : } // namespace 54 : 55 : #include <type_traits> // Brings in std::declval too. 56 : 57 : namespace std _GLIBCXX_VISIBILITY(default) 58 : { 59 : _GLIBCXX_BEGIN_NAMESPACE_VERSION 60 : 61 : /** 62 : * @addtogroup utilities 63 : * @{ 64 : */ 65 : 66 : /** 67 : * @brief Forward an lvalue. 68 : * @return The parameter cast to the specified type. 69 : * 70 : * This function is used to implement "perfect forwarding". 71 : */ 72 : template<typename _Tp> 73 : constexpr _Tp&& 74 5472371922 : forward(typename std::remove_reference<_Tp>::type& __t) noexcept 75 : { return static_cast<_Tp&&>(__t); } 76 : 77 : /** 78 : * @brief Forward an rvalue. 79 : * @return The parameter cast to the specified type. 80 : * 81 : * This function is used to implement "perfect forwarding". 82 : */ 83 : template<typename _Tp> 84 : constexpr _Tp&& 85 : forward(typename std::remove_reference<_Tp>::type&& __t) noexcept 86 : { 87 : static_assert(!std::is_lvalue_reference<_Tp>::value, "template argument" 88 : " substituting _Tp is an lvalue reference type"); 89 : return static_cast<_Tp&&>(__t); 90 : } 91 : 92 : /** 93 : * @brief Convert a value to an rvalue. 94 : * @param __t A thing of arbitrary type. 95 : * @return The parameter cast to an rvalue-reference to allow moving it. 96 : */ 97 : template<typename _Tp> 98 : constexpr typename std::remove_reference<_Tp>::type&& 99 3534348298 : move(_Tp&& __t) noexcept 100 : { return static_cast<typename std::remove_reference<_Tp>::type&&>(__t); } 101 : 102 : 103 : template<typename _Tp> 104 : struct __move_if_noexcept_cond 105 : : public __and_<__not_<is_nothrow_move_constructible<_Tp>>, 106 : is_copy_constructible<_Tp>>::type { }; 107 : 108 : /** 109 : * @brief Conditionally convert a value to an rvalue. 110 : * @param __x A thing of arbitrary type. 111 : * @return The parameter, possibly cast to an rvalue-reference. 112 : * 113 : * Same as std::move unless the type's move constructor could throw and the 114 : * type is copyable, in which case an lvalue-reference is returned instead. 115 : */ 116 : template<typename _Tp> 117 : constexpr typename 118 : conditional<__move_if_noexcept_cond<_Tp>::value, const _Tp&, _Tp&&>::type 119 : move_if_noexcept(_Tp& __x) noexcept 120 : { return std::move(__x); } 121 : 122 : // declval, from type_traits. 123 : 124 : #if __cplusplus > 201402L 125 : // _GLIBCXX_RESOLVE_LIB_DEFECTS 126 : // 2296. std::addressof should be constexpr 127 : # define __cpp_lib_addressof_constexpr 201603 128 : #endif 129 : /** 130 : * @brief Returns the actual address of the object or function 131 : * referenced by r, even in the presence of an overloaded 132 : * operator&. 133 : * @param __r Reference to an object or function. 134 : * @return The actual address. 135 : */ 136 : template<typename _Tp> 137 : inline _GLIBCXX17_CONSTEXPR _Tp* 138 5882226869 : addressof(_Tp& __r) noexcept 139 5741216431 : { return std::__addressof(__r); } 140 : 141 : // _GLIBCXX_RESOLVE_LIB_DEFECTS 142 : // 2598. addressof works on temporaries 143 : template<typename _Tp> 144 : const _Tp* addressof(const _Tp&&) = delete; 145 : 146 : // C++11 version of std::exchange for internal use. 147 : template <typename _Tp, typename _Up = _Tp> 148 : inline _Tp 149 : __exchange(_Tp& __obj, _Up&& __new_val) 150 : { 151 : _Tp __old_val = std::move(__obj); 152 : __obj = std::forward<_Up>(__new_val); 153 : return __old_val; 154 : } 155 : 156 : /// @} group utilities 157 : 158 : #define _GLIBCXX_MOVE(__val) std::move(__val) 159 : #define _GLIBCXX_FORWARD(_Tp, __val) std::forward<_Tp>(__val) 160 : #else 161 : #define _GLIBCXX_MOVE(__val) (__val) 162 : #define _GLIBCXX_FORWARD(_Tp, __val) (__val) 163 : #endif 164 : 165 : /** 166 : * @addtogroup utilities 167 : * @{ 168 : */ 169 : 170 : /** 171 : * @brief Swaps two values. 172 : * @param __a A thing of arbitrary type. 173 : * @param __b Another thing of arbitrary type. 174 : * @return Nothing. 175 : */ 176 : template<typename _Tp> 177 : inline 178 : #if __cplusplus >= 201103L 179 : typename enable_if<__and_<__not_<__is_tuple_like<_Tp>>, 180 : is_move_constructible<_Tp>, 181 : is_move_assignable<_Tp>>::value>::type 182 15282 : swap(_Tp& __a, _Tp& __b) 183 : noexcept(__and_<is_nothrow_move_constructible<_Tp>, 184 : is_nothrow_move_assignable<_Tp>>::value) 185 : #else 186 : void 187 : swap(_Tp& __a, _Tp& __b) 188 : #endif 189 : { 190 : // concept requirements 191 : __glibcxx_function_requires(_SGIAssignableConcept<_Tp>) 192 : 193 1910 : _Tp __tmp = _GLIBCXX_MOVE(__a); 194 955 : __a = _GLIBCXX_MOVE(__b); 195 15280 : __b = _GLIBCXX_MOVE(__tmp); 196 2 : } 197 : 198 : // _GLIBCXX_RESOLVE_LIB_DEFECTS 199 : // DR 809. std::swap should be overloaded for array types. 200 : /// Swap the contents of two arrays. 201 : template<typename _Tp, size_t _Nm> 202 : inline 203 : #if __cplusplus >= 201103L 204 : typename enable_if<__is_swappable<_Tp>::value>::type 205 : swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm]) 206 : noexcept(__is_nothrow_swappable<_Tp>::value) 207 : #else 208 : void 209 : swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm]) 210 : #endif 211 : { 212 : for (size_t __n = 0; __n < _Nm; ++__n) 213 : swap(__a[__n], __b[__n]); 214 : } 215 : 216 : /// @} group utilities 217 : _GLIBCXX_END_NAMESPACE_VERSION 218 : } // namespace 219 : 220 : #endif /* _MOVE_H */