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>>) &&
  46     requires (_T1&& __x, _T2&& __y) {
  47       // NOLINTNEXTLINE(libcpp-robust-against-adl) iter_swap ADL calls should only be made through ranges::iter_swap
  48       iter_swap(_VSTD::forward<_T1>(__x), _VSTD::forward<_T2>(__y));
  49     };
  50
  51   template<class _T1, class _T2>
  52   concept __readable_swappable =
  53     indirectly_readable<_T1> && indirectly_readable<_T2> &&
  54     swappable_with<iter_reference_t<_T1>, iter_reference_t<_T2>>;
  55
  56
  57   struct __fn {
  58     // NOLINTBEGIN(libcpp-robust-against-adl) iter_swap ADL calls should only be made through ranges::iter_swap
  59     template <class _T1, class _T2>
  60       requires __unqualified_iter_swap<_T1, _T2>
  61     _LIBCPP_HIDE_FROM_ABI
  62     constexpr void operator()(_T1&& __x, _T2&& __y) const
  63       noexcept(noexcept(iter_swap(_VSTD::forward<_T1>(__x), _VSTD::forward<_T2>(__y))))
  64     {
  65       (void)iter_swap(_VSTD::forward<_T1>(__x), _VSTD::forward<_T2>(__y));
  66     }
  67     // NOLINTEND(libcpp-robust-against-adl)
  68
  69     template <class _T1, class _T2>
  70       requires (!__unqualified_iter_swap<_T1, _T2>) &&
  71                __readable_swappable<_T1, _T2>
  72     _LIBCPP_HIDE_FROM_ABI
  73     constexpr void operator()(_T1&& __x, _T2&& __y) const
  74       noexcept(noexcept(ranges::swap(*_VSTD::forward<_T1>(__x), *_VSTD::forward<_T2>(__y))))
  75     {
  76       ranges::swap(*_VSTD::forward<_T1>(__x), *_VSTD::forward<_T2>(__y));
  77     }
  78
  79     template <class _T1, class _T2>
  80       requires (!__unqualified_iter_swap<_T1, _T2> &&
  81                 !__readable_swappable<_T1, _T2>) &&
  82                indirectly_movable_storable<_T1, _T2> &&
  83                indirectly_movable_storable<_T2, _T1>
  84     _LIBCPP_HIDE_FROM_ABI
  85     constexpr void operator()(_T1&& __x, _T2&& __y) const
  86       noexcept(noexcept(iter_value_t<_T2>(ranges::iter_move(__y))) &&
  87                noexcept(*__y = ranges::iter_move(__x)) &&
  88                noexcept(*_VSTD::forward<_T1>(__x) = std::declval<iter_value_t<_T2>>()))
  89     {
  90       iter_value_t<_T2> __old(ranges::iter_move(__y));
  91       *__y = ranges::iter_move(__x);
  92       *_VSTD::forward<_T1>(__x) = _VSTD::move(__old);
  93     }
  94   };
  95 } // namespace __iter_swap
  96
  97 inline namespace __cpo {
  98   inline constexpr auto iter_swap = __iter_swap::__fn{};
  99 } // namespace __cpo
 100 } // namespace ranges
 101
 102 template<class _I1, class _I2 = _I1>
 103 concept indirectly_swappable =
 104   indirectly_readable<_I1> && indirectly_readable<_I2> &&
 105   requires(const _I1 __i1, const _I2 __i2) {
 106     ranges::iter_swap(__i1, __i1);
 107     ranges::iter_swap(__i2, __i2);
 108     ranges::iter_swap(__i1, __i2);
 109     ranges::iter_swap(__i2, __i1);
 110   };
 111
 112 #endif // _LIBCPP_STD_VER >= 20
 113
 114 _LIBCPP_END_NAMESPACE_STD
 115
 116 _LIBCPP_POP_MACROS
 117
 118 #endif // _LIBCPP___ITERATOR_ITER_SWAP_H