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