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Editing: move.h
// Move, forward and identity for C++11 + swap -*- C++ -*- // Copyright (C) 2007-2018 Free Software Foundation, Inc. // // This file is part of the GNU ISO C++ Library. This library is free // software; you can redistribute it and/or modify it under the // terms of the GNU General Public License as published by the // Free Software Foundation; either version 3, or (at your option) // any later version. // This library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // Under Section 7 of GPL version 3, you are granted additional // permissions described in the GCC Runtime Library Exception, version // 3.1, as published by the Free Software Foundation. // You should have received a copy of the GNU General Public License and // a copy of the GCC Runtime Library Exception along with this program; // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see // <http://www.gnu.org/licenses/>. /** @file bits/move.h * This is an internal header file, included by other library headers. * Do not attempt to use it directly. @headername{utility} */ #ifndef _MOVE_H #define _MOVE_H 1 #include <bits/c++config.h> #include <bits/concept_check.h> namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION // Used, in C++03 mode too, by allocators, etc. /** * @brief Same as C++11 std::addressof * @ingroup utilities */ template<typename _Tp> inline _GLIBCXX_CONSTEXPR _Tp* __addressof(_Tp& __r) _GLIBCXX_NOEXCEPT { return __builtin_addressof(__r); } #if __cplusplus >= 201103L _GLIBCXX_END_NAMESPACE_VERSION } // namespace #include <type_traits> // Brings in std::declval too. namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION /** * @addtogroup utilities * @{ */ /** * @brief Forward an lvalue. * @return The parameter cast to the specified type. * * This function is used to implement "perfect forwarding". */ template<typename _Tp> constexpr _Tp&& forward(typename std::remove_reference<_Tp>::type& __t) noexcept { return static_cast<_Tp&&>(__t); } /** * @brief Forward an rvalue. * @return The parameter cast to the specified type. * * This function is used to implement "perfect forwarding". */ template<typename _Tp> constexpr _Tp&& forward(typename std::remove_reference<_Tp>::type&& __t) noexcept { static_assert(!std::is_lvalue_reference<_Tp>::value, "template argument" " substituting _Tp is an lvalue reference type"); return static_cast<_Tp&&>(__t); } /** * @brief Convert a value to an rvalue. * @param __t A thing of arbitrary type. * @return The parameter cast to an rvalue-reference to allow moving it. */ template<typename _Tp> constexpr typename std::remove_reference<_Tp>::type&& move(_Tp&& __t) noexcept { return static_cast<typename std::remove_reference<_Tp>::type&&>(__t); } template<typename _Tp> struct __move_if_noexcept_cond : public __and_<__not_<is_nothrow_move_constructible<_Tp>>, is_copy_constructible<_Tp>>::type { }; /** * @brief Conditionally convert a value to an rvalue. * @param __x A thing of arbitrary type. * @return The parameter, possibly cast to an rvalue-reference. * * Same as std::move unless the type's move constructor could throw and the * type is copyable, in which case an lvalue-reference is returned instead. */ template<typename _Tp> constexpr typename conditional<__move_if_noexcept_cond<_Tp>::value, const _Tp&, _Tp&&>::type move_if_noexcept(_Tp& __x) noexcept { return std::move(__x); } // declval, from type_traits. #if __cplusplus > 201402L // _GLIBCXX_RESOLVE_LIB_DEFECTS // 2296. std::addressof should be constexpr # define __cpp_lib_addressof_constexpr 201603 #endif /** * @brief Returns the actual address of the object or function * referenced by r, even in the presence of an overloaded * operator&. * @param __r Reference to an object or function. * @return The actual address. */ template<typename _Tp> inline _GLIBCXX17_CONSTEXPR _Tp* addressof(_Tp& __r) noexcept { return std::__addressof(__r); } // _GLIBCXX_RESOLVE_LIB_DEFECTS // 2598. addressof works on temporaries template<typename _Tp> const _Tp* addressof(const _Tp&&) = delete; // C++11 version of std::exchange for internal use. template <typename _Tp, typename _Up = _Tp> inline _Tp __exchange(_Tp& __obj, _Up&& __new_val) { _Tp __old_val = std::move(__obj); __obj = std::forward<_Up>(__new_val); return __old_val; } /// @} group utilities #define _GLIBCXX_MOVE(__val) std::move(__val) #define _GLIBCXX_FORWARD(_Tp, __val) std::forward<_Tp>(__val) #else #define _GLIBCXX_MOVE(__val) (__val) #define _GLIBCXX_FORWARD(_Tp, __val) (__val) #endif /** * @addtogroup utilities * @{ */ /** * @brief Swaps two values. * @param __a A thing of arbitrary type. * @param __b Another thing of arbitrary type. * @return Nothing. */ template<typename _Tp> inline #if __cplusplus >= 201103L typename enable_if<__and_<__not_<__is_tuple_like<_Tp>>, is_move_constructible<_Tp>, is_move_assignable<_Tp>>::value>::type swap(_Tp& __a, _Tp& __b) noexcept(__and_<is_nothrow_move_constructible<_Tp>, is_nothrow_move_assignable<_Tp>>::value) #else void swap(_Tp& __a, _Tp& __b) #endif { // concept requirements __glibcxx_function_requires(_SGIAssignableConcept<_Tp>) _Tp __tmp = _GLIBCXX_MOVE(__a); __a = _GLIBCXX_MOVE(__b); __b = _GLIBCXX_MOVE(__tmp); } // _GLIBCXX_RESOLVE_LIB_DEFECTS // DR 809. std::swap should be overloaded for array types. /// Swap the contents of two arrays. template<typename _Tp, size_t _Nm> inline #if __cplusplus >= 201103L typename enable_if<__is_swappable<_Tp>::value>::type swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm]) noexcept(__is_nothrow_swappable<_Tp>::value) #else void swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm]) #endif { for (size_t __n = 0; __n < _Nm; ++__n) swap(__a[__n], __b[__n]); } /// @} group utilities _GLIBCXX_END_NAMESPACE_VERSION } // namespace #endif /* _MOVE_H */
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