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