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_BEGIN_NAMESPACE_STD
27 
28 #if _LIBCPP_STD_VER > 17
29 
30 // [iterator.cust.move]
31 
32 namespace ranges {
33 namespace __iter_move {
34 
35 void iter_move();
36 
37 template <class _Tp>
38 concept __unqualified_iter_move =
39   __class_or_enum<remove_cvref_t<_Tp>> &&
40   requires (_Tp&& __t) {
41     // NOLINTNEXTLINE(libcpp-robust-against-adl) iter_swap ADL calls should only be made through ranges::iter_swap
42     iter_move(std::forward<_Tp>(__t));
43   };
44 
45 template<class _Tp>
46 concept __move_deref =
47   !__unqualified_iter_move<_Tp> &&
48   requires (_Tp&& __t) {
49     *__t;
50     requires is_lvalue_reference_v<decltype(*__t)>;
51   };
52 
53 template<class _Tp>
54 concept __just_deref =
55   !__unqualified_iter_move<_Tp> &&
56   !__move_deref<_Tp> &&
57   requires (_Tp&& __t) {
58     *__t;
59     requires (!is_lvalue_reference_v<decltype(*__t)>);
60   };
61 
62 // [iterator.cust.move]
63 
64 struct __fn {
65   // NOLINTBEGIN(libcpp-robust-against-adl) iter_move ADL calls should only be made through ranges::iter_move
66   template<class _Ip>
67     requires __unqualified_iter_move<_Ip>
68   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator()(_Ip&& __i) const
69     noexcept(noexcept(iter_move(std::forward<_Ip>(__i))))
70   {
71     return iter_move(std::forward<_Ip>(__i));
72   }
73   // NOLINTEND(libcpp-robust-against-adl)
74 
75   template<class _Ip>
76     requires __move_deref<_Ip>
77   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Ip&& __i) const
78     noexcept(noexcept(std::move(*std::forward<_Ip>(__i))))
79     -> decltype(      std::move(*std::forward<_Ip>(__i)))
80     { return          std::move(*std::forward<_Ip>(__i)); }
81 
82   template<class _Ip>
83     requires __just_deref<_Ip>
84   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Ip&& __i) const
85     noexcept(noexcept(*std::forward<_Ip>(__i)))
86     -> decltype(      *std::forward<_Ip>(__i))
87     { return          *std::forward<_Ip>(__i); }
88 };
89 } // namespace __iter_move
90 
91 inline namespace __cpo {
92   inline constexpr auto iter_move = __iter_move::__fn{};
93 } // namespace __cpo
94 } // namespace ranges
95 
96 template<__dereferenceable _Tp>
97   requires requires(_Tp& __t) { { ranges::iter_move(__t) } -> __can_reference; }
98 using iter_rvalue_reference_t = decltype(ranges::iter_move(std::declval<_Tp&>()));
99 
100 #endif // _LIBCPP_STD_VER > 17
101 
102 _LIBCPP_END_NAMESPACE_STD
103 
104 #endif // _LIBCPP___ITERATOR_ITER_MOVE_H
105