libcxx/include/__iterator/iter_move.h

   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