1 //===----------------------------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef _LIBCPP___CONCEPTS_SWAPPABLE_H 10 #define _LIBCPP___CONCEPTS_SWAPPABLE_H 11 12 #include <__concepts/assignable.h> 13 #include <__concepts/class_or_enum.h> 14 #include <__concepts/common_reference_with.h> 15 #include <__concepts/constructible.h> 16 #include <__config> 17 #include <__type_traits/extent.h> 18 #include <__type_traits/is_nothrow_assignable.h> 19 #include <__type_traits/is_nothrow_constructible.h> 20 #include <__type_traits/remove_cvref.h> 21 #include <__utility/exchange.h> 22 #include <__utility/forward.h> 23 #include <__utility/move.h> 24 #include <__utility/swap.h> 25 #include <cstddef> 26 27 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 28 # pragma GCC system_header 29 #endif 30 31 _LIBCPP_PUSH_MACROS 32 #include <__undef_macros> 33 34 _LIBCPP_BEGIN_NAMESPACE_STD 35 36 #if _LIBCPP_STD_VER >= 20 37 38 // [concept.swappable] 39 40 namespace ranges { 41 namespace __swap { 42 43 template <class _Tp> 44 void swap(_Tp&, _Tp&) = delete; 45 46 // clang-format off 47 template <class _Tp, class _Up> 48 concept __unqualified_swappable_with = 49 (__class_or_enum<remove_cvref_t<_Tp>> || __class_or_enum<remove_cvref_t<_Up>>) && 50 requires(_Tp&& __t, _Up&& __u) { 51 swap(std::forward<_Tp>(__t), std::forward<_Up>(__u)); 52 }; 53 // clang-format on 54 55 struct __fn; 56 57 // clang-format off 58 template <class _Tp, class _Up, size_t _Size> 59 concept __swappable_arrays = 60 !__unqualified_swappable_with<_Tp (&)[_Size], _Up (&)[_Size]> && 61 extent_v<_Tp> == extent_v<_Up> && 62 requires(_Tp (&__t)[_Size], _Up (&__u)[_Size], const __fn& __swap) { 63 __swap(__t[0], __u[0]); 64 }; 65 // clang-format on 66 67 template <class _Tp> 68 concept __exchangeable = 69 !__unqualified_swappable_with<_Tp&, _Tp&> && move_constructible<_Tp> && assignable_from<_Tp&, _Tp>; 70 71 struct __fn { 72 // 2.1 `S` is `(void)swap(E1, E2)`* if `E1` or `E2` has class or enumeration type and... 73 // *The name `swap` is used here unqualified. 74 template <class _Tp, class _Up> 75 requires __unqualified_swappable_with<_Tp, _Up> 76 _LIBCPP_HIDE_FROM_ABI constexpr void operator()(_Tp&& __t, _Up&& __u) const 77 noexcept(noexcept(swap(std::forward<_Tp>(__t), std::forward<_Up>(__u)))) { 78 swap(std::forward<_Tp>(__t), std::forward<_Up>(__u)); 79 } 80 81 // 2.2 Otherwise, if `E1` and `E2` are lvalues of array types with equal extent and... 82 template <class _Tp, class _Up, size_t _Size> 83 requires __swappable_arrays<_Tp, _Up, _Size> 84 _LIBCPP_HIDE_FROM_ABI constexpr void operator()(_Tp (&__t)[_Size], _Up (&__u)[_Size]) const 85 noexcept(noexcept((*this)(*__t, *__u))) { 86 // TODO(cjdb): replace with `ranges::swap_ranges`. 87 for (size_t __i = 0; __i < _Size; ++__i) { 88 (*this)(__t[__i], __u[__i]); 89 } 90 } 91 92 // 2.3 Otherwise, if `E1` and `E2` are lvalues of the same type `T` that models... 93 template <__exchangeable _Tp> 94 _LIBCPP_HIDE_FROM_ABI constexpr void operator()(_Tp& __x, _Tp& __y) const 95 noexcept(is_nothrow_move_constructible_v<_Tp> && is_nothrow_move_assignable_v<_Tp>) { 96 __y = std::exchange(__x, std::move(__y)); 97 } 98 }; 99 } // namespace __swap 100 101 inline namespace __cpo { 102 inline constexpr auto swap = __swap::__fn{}; 103 } // namespace __cpo 104 } // namespace ranges 105 106 template <class _Tp> 107 concept swappable = requires(_Tp& __a, _Tp& __b) { ranges::swap(__a, __b); }; 108 109 template <class _Tp, class _Up> 110 concept swappable_with = common_reference_with<_Tp, _Up> && requires(_Tp&& __t, _Up&& __u) { 111 ranges::swap(std::forward<_Tp>(__t), std::forward<_Tp>(__t)); 112 ranges::swap(std::forward<_Up>(__u), std::forward<_Up>(__u)); 113 ranges::swap(std::forward<_Tp>(__t), std::forward<_Up>(__u)); 114 ranges::swap(std::forward<_Up>(__u), std::forward<_Tp>(__t)); 115 }; 116 117 #endif // _LIBCPP_STD_VER >= 20 118 119 _LIBCPP_END_NAMESPACE_STD 120 121 _LIBCPP_POP_MACROS 122 123 #endif // _LIBCPP___CONCEPTS_SWAPPABLE_H 124