1 // -*- C++ -*-
2 //===----------------------------------------------------------------------===//
3 //
4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5 // See https://llvm.org/LICENSE.txt for license information.
6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #ifndef _LIBCPP___ITERATOR_ITER_SWAP_H
11 #define _LIBCPP___ITERATOR_ITER_SWAP_H
12 
13 #include <__concepts/class_or_enum.h>
14 #include <__concepts/swappable.h>
15 #include <__config>
16 #include <__iterator/concepts.h>
17 #include <__iterator/iter_move.h>
18 #include <__iterator/iterator_traits.h>
19 #include <__iterator/readable_traits.h>
20 #include <__type_traits/remove_cvref.h>
21 #include <__utility/declval.h>
22 #include <__utility/forward.h>
23 #include <__utility/move.h>
24 
25 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
26 #  pragma GCC system_header
27 #endif
28 
29 _LIBCPP_PUSH_MACROS
30 #include <__undef_macros>
31 
32 _LIBCPP_BEGIN_NAMESPACE_STD
33 
34 #if _LIBCPP_STD_VER >= 20
35 
36 // [iter.cust.swap]
37 
38 namespace ranges {
39 namespace __iter_swap {
40   template<class _I1, class _I2>
41   void iter_swap(_I1, _I2) = delete;
42 
43   template<class _T1, class _T2>
44   concept __unqualified_iter_swap =
45     (__class_or_enum<remove_cvref_t<_T1>> || __class_or_enum<remove_cvref_t<_T2>>) &&
46     requires (_T1&& __x, _T2&& __y) {
47       // NOLINTNEXTLINE(libcpp-robust-against-adl) iter_swap ADL calls should only be made through ranges::iter_swap
48       iter_swap(std::forward<_T1>(__x), std::forward<_T2>(__y));
49     };
50 
51   template<class _T1, class _T2>
52   concept __readable_swappable =
53     indirectly_readable<_T1> && indirectly_readable<_T2> &&
54     swappable_with<iter_reference_t<_T1>, iter_reference_t<_T2>>;
55 
56 
57   struct __fn {
58     // NOLINTBEGIN(libcpp-robust-against-adl) iter_swap ADL calls should only be made through ranges::iter_swap
59     template <class _T1, class _T2>
60       requires __unqualified_iter_swap<_T1, _T2>
61     _LIBCPP_HIDE_FROM_ABI
62     constexpr void operator()(_T1&& __x, _T2&& __y) const
63       noexcept(noexcept(iter_swap(std::forward<_T1>(__x), std::forward<_T2>(__y))))
64     {
65       (void)iter_swap(std::forward<_T1>(__x), std::forward<_T2>(__y));
66     }
67     // NOLINTEND(libcpp-robust-against-adl)
68 
69     template <class _T1, class _T2>
70       requires (!__unqualified_iter_swap<_T1, _T2>) &&
71                __readable_swappable<_T1, _T2>
72     _LIBCPP_HIDE_FROM_ABI
73     constexpr void operator()(_T1&& __x, _T2&& __y) const
74       noexcept(noexcept(ranges::swap(*std::forward<_T1>(__x), *std::forward<_T2>(__y))))
75     {
76       ranges::swap(*std::forward<_T1>(__x), *std::forward<_T2>(__y));
77     }
78 
79     template <class _T1, class _T2>
80       requires (!__unqualified_iter_swap<_T1, _T2> && //
81                 !__readable_swappable<_T1, _T2>) && //
82                indirectly_movable_storable<_T1, _T2> && //
83                indirectly_movable_storable<_T2, _T1>
84     _LIBCPP_HIDE_FROM_ABI
85     constexpr void operator()(_T1&& __x, _T2&& __y) const
86       noexcept(noexcept(iter_value_t<_T2>(ranges::iter_move(__y))) && //
87                noexcept(*__y = ranges::iter_move(__x)) && //
88                noexcept(*std::forward<_T1>(__x) = std::declval<iter_value_t<_T2>>()))
89     {
90       iter_value_t<_T2> __old(ranges::iter_move(__y));
91       *__y = ranges::iter_move(__x);
92       *std::forward<_T1>(__x) = std::move(__old);
93     }
94   };
95 } // namespace __iter_swap
96 
97 inline namespace __cpo {
98   inline constexpr auto iter_swap = __iter_swap::__fn{};
99 } // namespace __cpo
100 } // namespace ranges
101 
102 template<class _I1, class _I2 = _I1>
103 concept indirectly_swappable =
104   indirectly_readable<_I1> && indirectly_readable<_I2> &&
105   requires(const _I1 __i1, const _I2 __i2) {
106     ranges::iter_swap(__i1, __i1);
107     ranges::iter_swap(__i2, __i2);
108     ranges::iter_swap(__i1, __i2);
109     ranges::iter_swap(__i2, __i1);
110   };
111 
112 #endif // _LIBCPP_STD_VER >= 20
113 
114 _LIBCPP_END_NAMESPACE_STD
115 
116 _LIBCPP_POP_MACROS
117 
118 #endif // _LIBCPP___ITERATOR_ITER_SWAP_H
119