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 #ifndef _LIBCPP___ITERATOR_ITER_SWAP_H
10 #define _LIBCPP___ITERATOR_ITER_SWAP_H
11 
12 #include <__config>
13 #include <__iterator/concepts.h>
14 #include <__iterator/iter_move.h>
15 #include <__iterator/iterator_traits.h>
16 #include <__iterator/readable_traits.h>
17 #include <__ranges/access.h>
18 #include <concepts>
19 #include <type_traits>
20 
21 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
22 #pragma GCC system_header
23 #endif
24 
25 _LIBCPP_PUSH_MACROS
26 #include <__undef_macros>
27 
28 _LIBCPP_BEGIN_NAMESPACE_STD
29 
30 #if !defined(_LIBCPP_HAS_NO_RANGES)
31 
32 namespace ranges {
33 namespace __iter_swap {
34   template<class _I1, class _I2>
35   void iter_swap(_I1, _I2) = delete;
36 
37   template<class _T1, class _T2>
38   concept __unqualified_iter_swap = requires(_T1&& __x, _T2&& __y) {
39     iter_swap(_VSTD::forward<_T1>(__x), _VSTD::forward<_T2>(__y));
40   };
41 
42   template<class _T1, class _T2>
43   concept __readable_swappable =
44     indirectly_readable<_T1> && indirectly_readable<_T2> &&
45     swappable_with<iter_reference_t<_T1>, iter_reference_t<_T2>>;
46 
47   struct __fn {
48     template <class _T1, class _T2>
49       requires __unqualified_iter_swap<_T1, _T2>
50     _LIBCPP_HIDE_FROM_ABI
51     constexpr void operator()(_T1&& __x, _T2&& __y) const
52       noexcept(noexcept(iter_swap(_VSTD::forward<_T1>(__x), _VSTD::forward<_T2>(__y))))
53     {
54       (void)iter_swap(_VSTD::forward<_T1>(__x), _VSTD::forward<_T2>(__y));
55     }
56 
57     template <class _T1, class _T2>
58       requires (!__unqualified_iter_swap<_T1, _T2>) &&
59                __readable_swappable<_T1, _T2>
60     _LIBCPP_HIDE_FROM_ABI
61     constexpr void operator()(_T1&& __x, _T2&& __y) const
62       noexcept(noexcept(ranges::swap(*_VSTD::forward<_T1>(__x), *_VSTD::forward<_T2>(__y))))
63     {
64       ranges::swap(*_VSTD::forward<_T1>(__x), *_VSTD::forward<_T2>(__y));
65     }
66 
67     template <class _T1, class _T2>
68       requires (!__unqualified_iter_swap<_T1, _T2> &&
69                 !__readable_swappable<_T1, _T2>) &&
70                indirectly_movable_storable<_T1, _T2> &&
71                indirectly_movable_storable<_T2, _T1>
72     _LIBCPP_HIDE_FROM_ABI
73     constexpr void operator()(_T1&& __x, _T2&& __y) const
74       noexcept(noexcept(iter_value_t<_T2>(ranges::iter_move(__y))) &&
75                noexcept(*__y = ranges::iter_move(__x)) &&
76                noexcept(*_VSTD::forward<_T1>(__x) = declval<iter_value_t<_T2>>()))
77     {
78       iter_value_t<_T2> __old(ranges::iter_move(__y));
79       *__y = ranges::iter_move(__x);
80       *_VSTD::forward<_T1>(__x) = _VSTD::move(__old);
81     }
82   };
83 } // end namespace __iter_swap
84 
85 inline namespace __cpo {
86   inline constexpr auto iter_swap = __iter_swap::__fn{};
87 } // namespace __cpo
88 
89 } // namespace ranges
90 
91 template<class _I1, class _I2 = _I1>
92 concept indirectly_swappable =
93   indirectly_readable<_I1> && indirectly_readable<_I2> &&
94   requires(const _I1 __i1, const _I2 __i2) {
95     ranges::iter_swap(__i1, __i1);
96     ranges::iter_swap(__i2, __i2);
97     ranges::iter_swap(__i1, __i2);
98     ranges::iter_swap(__i2, __i1);
99   };
100 
101 #endif // !defined(_LIBCPP_HAS_NO_RANGES)
102 
103 _LIBCPP_END_NAMESPACE_STD
104 
105 _LIBCPP_POP_MACROS
106 
107 #endif // _LIBCPP___ITERATOR_ITER_SWAP_H
108