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 <__utility/exchange.h> 18 #include <__utility/forward.h> 19 #include <__utility/move.h> 20 #include <type_traits> 21 22 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 23 # pragma GCC system_header 24 #endif 25 26 _LIBCPP_BEGIN_NAMESPACE_STD 27 28 #if _LIBCPP_STD_VER > 17 29 30 // [concept.swappable] 31 32 namespace ranges { 33 namespace __swap { 34 35 template<class _Tp> 36 void swap(_Tp&, _Tp&) = delete; 37 38 template<class _Tp, class _Up> 39 concept __unqualified_swappable_with = 40 (__class_or_enum<remove_cvref_t<_Tp>> || __class_or_enum<remove_cvref_t<_Up>>) && 41 requires(_Tp&& __t, _Up&& __u) { 42 swap(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u)); 43 }; 44 45 struct __fn; 46 47 template<class _Tp, class _Up, size_t _Size> 48 concept __swappable_arrays = 49 !__unqualified_swappable_with<_Tp(&)[_Size], _Up(&)[_Size]> && 50 extent_v<_Tp> == extent_v<_Up> && 51 requires(_Tp(& __t)[_Size], _Up(& __u)[_Size], const __fn& __swap) { 52 __swap(__t[0], __u[0]); 53 }; 54 55 template<class _Tp> 56 concept __exchangeable = 57 !__unqualified_swappable_with<_Tp&, _Tp&> && 58 move_constructible<_Tp> && 59 assignable_from<_Tp&, _Tp>; 60 61 struct __fn { 62 // 2.1 `S` is `(void)swap(E1, E2)`* if `E1` or `E2` has class or enumeration type and... 63 // *The name `swap` is used here unqualified. 64 template<class _Tp, class _Up> 65 requires __unqualified_swappable_with<_Tp, _Up> 66 constexpr void operator()(_Tp&& __t, _Up&& __u) const 67 noexcept(noexcept(swap(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u)))) 68 { 69 swap(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u)); 70 } 71 72 // 2.2 Otherwise, if `E1` and `E2` are lvalues of array types with equal extent and... 73 template<class _Tp, class _Up, size_t _Size> 74 requires __swappable_arrays<_Tp, _Up, _Size> 75 constexpr void operator()(_Tp(& __t)[_Size], _Up(& __u)[_Size]) const 76 noexcept(noexcept((*this)(*__t, *__u))) 77 { 78 // TODO(cjdb): replace with `ranges::swap_ranges`. 79 for (size_t __i = 0; __i < _Size; ++__i) { 80 (*this)(__t[__i], __u[__i]); 81 } 82 } 83 84 // 2.3 Otherwise, if `E1` and `E2` are lvalues of the same type `T` that models... 85 template<__exchangeable _Tp> 86 constexpr void operator()(_Tp& __x, _Tp& __y) const 87 noexcept(is_nothrow_move_constructible_v<_Tp> && is_nothrow_move_assignable_v<_Tp>) 88 { 89 __y = _VSTD::exchange(__x, _VSTD::move(__y)); 90 } 91 }; 92 } // namespace __swap 93 94 inline namespace __cpo { 95 inline constexpr auto swap = __swap::__fn{}; 96 } // namespace __cpo 97 } // namespace ranges 98 99 template<class _Tp> 100 concept swappable = requires(_Tp& __a, _Tp& __b) { ranges::swap(__a, __b); }; 101 102 template<class _Tp, class _Up> 103 concept swappable_with = 104 common_reference_with<_Tp, _Up> && 105 requires(_Tp&& __t, _Up&& __u) { 106 ranges::swap(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Tp>(__t)); 107 ranges::swap(_VSTD::forward<_Up>(__u), _VSTD::forward<_Up>(__u)); 108 ranges::swap(_VSTD::forward<_Tp>(__t), _VSTD::forward<_Up>(__u)); 109 ranges::swap(_VSTD::forward<_Up>(__u), _VSTD::forward<_Tp>(__t)); 110 }; 111 112 #endif // _LIBCPP_STD_VER > 17 113 114 _LIBCPP_END_NAMESPACE_STD 115 116 #endif // _LIBCPP___CONCEPTS_SWAPPABLE_H 117