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_MOVE_H
11 #define _LIBCPP___ITERATOR_ITER_MOVE_H
12 
13 #include <__concepts/class_or_enum.h>
14 #include <__config>
15 #include <__iterator/iterator_traits.h>
16 #include <__type_traits/is_reference.h>
17 #include <__type_traits/remove_cvref.h>
18 #include <__utility/declval.h>
19 #include <__utility/forward.h>
20 #include <__utility/move.h>
21 
22 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
23 #  pragma GCC system_header
24 #endif
25 
26 _LIBCPP_PUSH_MACROS
27 #include <__undef_macros>
28 
29 _LIBCPP_BEGIN_NAMESPACE_STD
30 
31 #if _LIBCPP_STD_VER >= 20
32 
33 // [iterator.cust.move]
34 
35 namespace ranges {
36 namespace __iter_move {
37 
38 void iter_move();
39 
40 template <class _Tp>
41 concept __unqualified_iter_move =
42   __class_or_enum<remove_cvref_t<_Tp>> &&
43   requires (_Tp&& __t) {
44     // NOLINTNEXTLINE(libcpp-robust-against-adl) iter_swap ADL calls should only be made through ranges::iter_swap
45     iter_move(std::forward<_Tp>(__t));
46   };
47 
48 template<class _Tp>
49 concept __move_deref =
50   !__unqualified_iter_move<_Tp> &&
51   requires (_Tp&& __t) {
52     *__t;
53     requires is_lvalue_reference_v<decltype(*__t)>;
54   };
55 
56 template<class _Tp>
57 concept __just_deref =
58   !__unqualified_iter_move<_Tp> &&
59   !__move_deref<_Tp> &&
60   requires (_Tp&& __t) {
61     *__t;
62     requires (!is_lvalue_reference_v<decltype(*__t)>);
63   };
64 
65 // [iterator.cust.move]
66 
67 struct __fn {
68   // NOLINTBEGIN(libcpp-robust-against-adl) iter_move ADL calls should only be made through ranges::iter_move
69   template<class _Ip>
70     requires __unqualified_iter_move<_Ip>
71   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator()(_Ip&& __i) const
72     noexcept(noexcept(iter_move(std::forward<_Ip>(__i))))
73   {
74     return iter_move(std::forward<_Ip>(__i));
75   }
76   // NOLINTEND(libcpp-robust-against-adl)
77 
78   template<class _Ip>
79     requires __move_deref<_Ip>
80   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Ip&& __i) const
81     noexcept(noexcept(std::move(*std::forward<_Ip>(__i))))
82     -> decltype(      std::move(*std::forward<_Ip>(__i)))
83     { return          std::move(*std::forward<_Ip>(__i)); }
84 
85   template<class _Ip>
86     requires __just_deref<_Ip>
87   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Ip&& __i) const
88     noexcept(noexcept(*std::forward<_Ip>(__i)))
89     -> decltype(      *std::forward<_Ip>(__i))
90     { return          *std::forward<_Ip>(__i); }
91 };
92 } // namespace __iter_move
93 
94 inline namespace __cpo {
95   inline constexpr auto iter_move = __iter_move::__fn{};
96 } // namespace __cpo
97 } // namespace ranges
98 
99 template<__dereferenceable _Tp>
100   requires requires(_Tp& __t) { { ranges::iter_move(__t) } -> __can_reference; }
101 using iter_rvalue_reference_t = decltype(ranges::iter_move(std::declval<_Tp&>()));
102 
103 #endif // _LIBCPP_STD_VER >= 20
104 
105 _LIBCPP_END_NAMESPACE_STD
106 
107 _LIBCPP_POP_MACROS
108 
109 #endif // _LIBCPP___ITERATOR_ITER_MOVE_H
110