forked from OSchip/llvm-project
117 lines
3.7 KiB
C++
117 lines
3.7 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___CONCEPTS_SWAPPABLE_H
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#define _LIBCPP___CONCEPTS_SWAPPABLE_H
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#include <__concepts/assignable.h>
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#include <__concepts/class_or_enum.h>
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#include <__concepts/common_reference_with.h>
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#include <__concepts/constructible.h>
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#include <__config>
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#include <__utility/exchange.h>
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#include <__utility/forward.h>
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#include <__utility/move.h>
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#include <type_traits>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_BEGIN_NAMESPACE_STD
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#if _LIBCPP_STD_VER > 17
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// [concept.swappable]
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namespace ranges {
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namespace __swap {
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template<class _Tp>
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void swap(_Tp&, _Tp&) = delete;
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template<class _Tp, class _Up>
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concept __unqualified_swappable_with =
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(__class_or_enum<remove_cvref_t<_Tp>> || __class_or_enum<remove_cvref_t<_Up>>) &&
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requires(_Tp&& __t, _Up&& __u) {
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swap(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u));
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};
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struct __fn;
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template<class _Tp, class _Up, size_t _Size>
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concept __swappable_arrays =
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!__unqualified_swappable_with<_Tp(&)[_Size], _Up(&)[_Size]> &&
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extent_v<_Tp> == extent_v<_Up> &&
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requires(_Tp(& __t)[_Size], _Up(& __u)[_Size], const __fn& __swap) {
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__swap(__t[0], __u[0]);
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};
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template<class _Tp>
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concept __exchangeable =
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!__unqualified_swappable_with<_Tp&, _Tp&> &&
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move_constructible<_Tp> &&
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assignable_from<_Tp&, _Tp>;
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struct __fn {
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// 2.1 `S` is `(void)swap(E1, E2)`* if `E1` or `E2` has class or enumeration type and...
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// *The name `swap` is used here unqualified.
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template<class _Tp, class _Up>
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requires __unqualified_swappable_with<_Tp, _Up>
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constexpr void operator()(_Tp&& __t, _Up&& __u) const
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noexcept(noexcept(swap(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u))))
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{
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swap(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u));
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}
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// 2.2 Otherwise, if `E1` and `E2` are lvalues of array types with equal extent and...
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template<class _Tp, class _Up, size_t _Size>
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requires __swappable_arrays<_Tp, _Up, _Size>
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constexpr void operator()(_Tp(& __t)[_Size], _Up(& __u)[_Size]) const
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noexcept(noexcept((*this)(*__t, *__u)))
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{
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// TODO(cjdb): replace with `ranges::swap_ranges`.
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for (size_t __i = 0; __i < _Size; ++__i) {
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(*this)(__t[__i], __u[__i]);
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}
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}
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// 2.3 Otherwise, if `E1` and `E2` are lvalues of the same type `T` that models...
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template<__exchangeable _Tp>
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constexpr void operator()(_Tp& __x, _Tp& __y) const
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noexcept(is_nothrow_move_constructible_v<_Tp> && is_nothrow_move_assignable_v<_Tp>)
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{
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__y = _VSTD::exchange(__x, _VSTD::move(__y));
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}
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};
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} // namespace __swap
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inline namespace __cpo {
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inline constexpr auto swap = __swap::__fn{};
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} // namespace __cpo
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} // namespace ranges
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template<class _Tp>
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concept swappable = requires(_Tp& __a, _Tp& __b) { ranges::swap(__a, __b); };
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template<class _Tp, class _Up>
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concept swappable_with =
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common_reference_with<_Tp, _Up> &&
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requires(_Tp&& __t, _Up&& __u) {
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ranges::swap(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Tp>(__t));
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ranges::swap(_VSTD::forward<_Up>(__u), _VSTD::forward<_Up>(__u));
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ranges::swap(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u));
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ranges::swap(_VSTD::forward<_Up>(__u), _VSTD::forward<_Tp>(__t));
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};
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#endif // _LIBCPP_STD_VER > 17
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___CONCEPTS_SWAPPABLE_H
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