1 // Move, forward and identity for C++0x + swap -*- C++ -*- 2 3 // Copyright (C) 2007, 2008, 2009, 2010, 2011 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 _Tp* 47 __addressof(_Tp& __r) _GLIBCXX_NOEXCEPT 48 { 49 return reinterpret_cast<_Tp*> 50 (&const_cast<char&>(reinterpret_cast<const volatile char&>(__r))); 51 } 52 53 _GLIBCXX_END_NAMESPACE_VERSION 54 } // namespace 55 56 #ifdef __GXX_EXPERIMENTAL_CXX0X__ 57 #include <type_traits> // Brings in std::declval too. 58 59 namespace std _GLIBCXX_VISIBILITY(default) 60 { 61 _GLIBCXX_BEGIN_NAMESPACE_VERSION 62 63 /** 64 * @addtogroup utilities 65 * @{ 66 */ 67 68 // forward (as per N3143) 69 /** 70 * @brief Forward an lvalue. 71 * @return The parameter cast to the specified type. 72 * 73 * This function is used to implement "perfect forwarding". 74 */ 75 template<typename _Tp> 76 constexpr _Tp&& 77 forward(typename std::remove_reference<_Tp>::type& __t) noexcept 78 { return static_cast<_Tp&&>(__t); } 79 80 /** 81 * @brief Forward an rvalue. 82 * @return The parameter cast to the specified type. 83 * 84 * This function is used to implement "perfect forwarding". 85 */ 86 template<typename _Tp> 87 constexpr _Tp&& 88 forward(typename std::remove_reference<_Tp>::type&& __t) noexcept 89 { 90 static_assert(!std::is_lvalue_reference<_Tp>::value, "template argument" 91 " substituting _Tp is an lvalue reference type"); 92 return static_cast<_Tp&&>(__t); 93 } 94 95 /** 96 * @brief Convert a value to an rvalue. 97 * @param __t A thing of arbitrary type. 98 * @return The parameter cast to an rvalue-reference to allow moving it. 99 */ 100 template<typename _Tp> 101 constexpr typename std::remove_reference<_Tp>::type&& 102 move(_Tp&& __t) noexcept 103 { return static_cast<typename std::remove_reference<_Tp>::type&&>(__t); } 104 105 106 template<typename _Tp> 107 struct __move_if_noexcept_cond 108 : public __and_<__not_<is_nothrow_move_constructible<_Tp>>, 109 is_copy_constructible<_Tp>>::type { }; 110 111 /** 112 * @brief Conditionally convert a value to an rvalue. 113 * @param __x A thing of arbitrary type. 114 * @return The parameter, possibly cast to an rvalue-reference. 115 * 116 * Same as std::move unless the type's move constructor could throw and the 117 * type is copyable, in which case an lvalue-reference is returned instead. 118 */ 119 template<typename _Tp> 120 inline typename 121 conditional<__move_if_noexcept_cond<_Tp>::value, const _Tp&, _Tp&&>::type 122 move_if_noexcept(_Tp& __x) noexcept 123 { return std::move(__x); } 124 125 // declval, from type_traits. 126 127 /** 128 * @brief Returns the actual address of the object or function 129 * referenced by r, even in the presence of an overloaded 130 * operator&. 131 * @param __r Reference to an object or function. 132 * @return The actual address. 133 */ 134 template<typename _Tp> 135 inline _Tp* 136 addressof(_Tp& __r) noexcept 137 { return std::__addressof(__r); } 138 139 /// @} group utilities 140 _GLIBCXX_END_NAMESPACE_VERSION 141 } // namespace 142 143 #define _GLIBCXX_MOVE(__val) std::move(__val) 144 #define _GLIBCXX_FORWARD(_Tp, __val) std::forward<_Tp>(__val) 145 #else 146 #define _GLIBCXX_MOVE(__val) (__val) 147 #define _GLIBCXX_FORWARD(_Tp, __val) (__val) 148 #endif 149 150 namespace std _GLIBCXX_VISIBILITY(default) 151 { 152 _GLIBCXX_BEGIN_NAMESPACE_VERSION 153 154 /** 155 * @addtogroup utilities 156 * @{ 157 */ 158 159 /** 160 * @brief Swaps two values. 161 * @param __a A thing of arbitrary type. 162 * @param __b Another thing of arbitrary type. 163 * @return Nothing. 164 */ 165 template<typename _Tp> 166 inline void 167 swap(_Tp& __a, _Tp& __b) 168 #ifdef __GXX_EXPERIMENTAL_CXX0X__ 169 noexcept(__and_<is_nothrow_move_constructible<_Tp>, 170 is_nothrow_move_assignable<_Tp>>::value) 171 #endif 172 { 173 // concept requirements 174 __glibcxx_function_requires(_SGIAssignableConcept<_Tp>) 175 176 _Tp __tmp = _GLIBCXX_MOVE(__a); 177 __a = _GLIBCXX_MOVE(__b); 178 __b = _GLIBCXX_MOVE(__tmp); 179 } 180 181 // _GLIBCXX_RESOLVE_LIB_DEFECTS 182 // DR 809. std::swap should be overloaded for array types. 183 /// Swap the contents of two arrays. 184 template<typename _Tp, size_t _Nm> 185 inline void 186 swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm]) 187 #ifdef __GXX_EXPERIMENTAL_CXX0X__ 188 noexcept(noexcept(swap(*__a, *__b))) 189 #endif 190 { 191 for (size_t __n = 0; __n < _Nm; ++__n) 192 swap(__a[__n], __b[__n]); 193 } 194 195 /// @} group utilities 196 _GLIBCXX_END_NAMESPACE_VERSION 197 } // namespace 198 199 #endif /* _MOVE_H */ 200
