| // Move, forward and identity for C++11 + swap -*- C++ -*- |
| |
| // Copyright (C) 2007-2022 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> |
| #if __cplusplus < 201103L |
| # include <bits/concept_check.h> |
| #endif |
| |
| 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> |
| _GLIBCXX_NODISCARD |
| 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> |
| _GLIBCXX_NODISCARD |
| constexpr _Tp&& |
| forward(typename std::remove_reference<_Tp>::type&& __t) noexcept |
| { |
| static_assert(!std::is_lvalue_reference<_Tp>::value, |
| "std::forward must not be used to convert an rvalue to an lvalue"); |
| 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> |
| _GLIBCXX_NODISCARD |
| 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> |
| _GLIBCXX_NODISCARD |
| constexpr |
| __conditional_t<__move_if_noexcept_cond<_Tp>::value, const _Tp&, _Tp&&> |
| 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 201603L |
| #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> |
| _GLIBCXX_NODISCARD |
| 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> |
| _GLIBCXX20_CONSTEXPR |
| 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_FWDREF(_Tp) _Tp&& |
| #define _GLIBCXX_MOVE(__val) std::move(__val) |
| #define _GLIBCXX_FORWARD(_Tp, __val) std::forward<_Tp>(__val) |
| #else |
| #define _GLIBCXX_FWDREF(_Tp) const _Tp& |
| #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> |
| _GLIBCXX20_CONSTEXPR |
| inline |
| #if __cplusplus >= 201103L |
| typename enable_if<__and_<__not_<__is_tuple_like<_Tp>>, |
| is_move_constructible<_Tp>, |
| is_move_assignable<_Tp>>::value>::type |
| #else |
| void |
| #endif |
| swap(_Tp& __a, _Tp& __b) |
| _GLIBCXX_NOEXCEPT_IF(__and_<is_nothrow_move_constructible<_Tp>, |
| is_nothrow_move_assignable<_Tp>>::value) |
| { |
| #if __cplusplus < 201103L |
| // concept requirements |
| __glibcxx_function_requires(_SGIAssignableConcept<_Tp>) |
| #endif |
| _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> |
| _GLIBCXX20_CONSTEXPR |
| inline |
| #if __cplusplus >= 201103L |
| typename enable_if<__is_swappable<_Tp>::value>::type |
| #else |
| void |
| #endif |
| swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm]) |
| _GLIBCXX_NOEXCEPT_IF(__is_nothrow_swappable<_Tp>::value) |
| { |
| for (size_t __n = 0; __n < _Nm; ++__n) |
| swap(__a[__n], __b[__n]); |
| } |
| |
| /// @} group utilities |
| _GLIBCXX_END_NAMESPACE_VERSION |
| } // namespace |
| |
| #endif /* _MOVE_H */ |