libcxx/include/__ranges/access.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___RANGES_ACCESS_H
  11 #define _LIBCPP___RANGES_ACCESS_H
  12
  13 #include <__concepts/class_or_enum.h>
  14 #include <__config>
  15 #include <__iterator/concepts.h>
  16 #include <__iterator/readable_traits.h>
  17 #include <__ranges/enable_borrowed_range.h>
  18 #include <__type_traits/decay.h>
  19 #include <__type_traits/is_reference.h>
  20 #include <__type_traits/remove_cvref.h>
  21 #include <__type_traits/remove_reference.h>
  22 #include <__utility/auto_cast.h>
  23 #include <__utility/declval.h>
  24 #include <cstddef>
  25
  26 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  27 #  pragma GCC system_header
  28 #endif
  29
  30 _LIBCPP_BEGIN_NAMESPACE_STD
  31
  32 #if _LIBCPP_STD_VER >= 20
  33
  34 namespace ranges {
  35   template <class _Tp>
  36   concept __can_borrow =
  37     is_lvalue_reference_v<_Tp> || enable_borrowed_range<remove_cvref_t<_Tp>>;
  38 } // namespace ranges
  39
  40 // [range.access.begin]
  41
  42 namespace ranges {
  43 namespace __begin {
  44   template <class _Tp>
  45   concept __member_begin =
  46     __can_borrow<_Tp> &&
  47     __workaround_52970<_Tp> &&
  48     requires(_Tp&& __t) {
  49       { _LIBCPP_AUTO_CAST(__t.begin()) } -> input_or_output_iterator;
  50     };
  51
  52   void begin(auto&) = delete;
  53   void begin(const auto&) = delete;
  54
  55   template <class _Tp>
  56   concept __unqualified_begin =
  57     !__member_begin<_Tp> &&
  58     __can_borrow<_Tp> &&
  59     __class_or_enum<remove_cvref_t<_Tp>> &&
  60     requires(_Tp && __t) {
  61       { _LIBCPP_AUTO_CAST(begin(__t)) } -> input_or_output_iterator;
  62     };
  63
  64   struct __fn {
  65     template <class _Tp>
  66     [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp (&__t)[]) const noexcept
  67       requires (sizeof(_Tp) >= 0)  // Disallow incomplete element types.
  68     {
  69       return __t + 0;
  70     }
  71
  72     template <class _Tp, size_t _Np>
  73     [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp (&__t)[_Np]) const noexcept
  74       requires (sizeof(_Tp) >= 0)  // Disallow incomplete element types.
  75     {
  76       return __t + 0;
  77     }
  78
  79     template <class _Tp>
  80       requires __member_begin<_Tp>
  81     [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
  82       noexcept(noexcept(_LIBCPP_AUTO_CAST(__t.begin())))
  83     {
  84       return _LIBCPP_AUTO_CAST(__t.begin());
  85     }
  86
  87     template <class _Tp>
  88       requires __unqualified_begin<_Tp>
  89     [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
  90       noexcept(noexcept(_LIBCPP_AUTO_CAST(begin(__t))))
  91     {
  92       return _LIBCPP_AUTO_CAST(begin(__t));
  93     }
  94
  95     void operator()(auto&&) const = delete;
  96   };
  97 } // namespace __begin
  98
  99 inline namespace __cpo {
 100   inline constexpr auto begin = __begin::__fn{};
 101 } // namespace __cpo
 102 } // namespace ranges
 103
 104 // [range.range]
 105
 106 namespace ranges {
 107   template <class _Tp>
 108   using iterator_t = decltype(ranges::begin(std::declval<_Tp&>()));
 109 } // namespace ranges
 110
 111 // [range.access.end]
 112
 113 namespace ranges {
 114 namespace __end {
 115   template <class _Tp>
 116   concept __member_end =
 117     __can_borrow<_Tp> &&
 118     __workaround_52970<_Tp> &&
 119     requires(_Tp&& __t) {
 120       typename iterator_t<_Tp>;
 121       { _LIBCPP_AUTO_CAST(__t.end()) } -> sentinel_for<iterator_t<_Tp>>;
 122     };
 123
 124   void end(auto&) = delete;
 125   void end(const auto&) = delete;
 126
 127   template <class _Tp>
 128   concept __unqualified_end =
 129     !__member_end<_Tp> &&
 130     __can_borrow<_Tp> &&
 131     __class_or_enum<remove_cvref_t<_Tp>> &&
 132     requires(_Tp && __t) {
 133       typename iterator_t<_Tp>;
 134       { _LIBCPP_AUTO_CAST(end(__t)) } -> sentinel_for<iterator_t<_Tp>>;
 135     };
 136
 137   struct __fn {
 138     template <class _Tp, size_t _Np>
 139     [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp (&__t)[_Np]) const noexcept
 140       requires (sizeof(_Tp) >= 0)  // Disallow incomplete element types.
 141     {
 142       return __t + _Np;
 143     }
 144
 145     template <class _Tp>
 146       requires __member_end<_Tp>
 147     [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
 148       noexcept(noexcept(_LIBCPP_AUTO_CAST(__t.end())))
 149     {
 150       return _LIBCPP_AUTO_CAST(__t.end());
 151     }
 152
 153     template <class _Tp>
 154       requires __unqualified_end<_Tp>
 155     [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
 156       noexcept(noexcept(_LIBCPP_AUTO_CAST(end(__t))))
 157     {
 158       return _LIBCPP_AUTO_CAST(end(__t));
 159     }
 160
 161     void operator()(auto&&) const = delete;
 162   };
 163 } // namespace __end
 164
 165 inline namespace __cpo {
 166   inline constexpr auto end = __end::__fn{};
 167 } // namespace __cpo
 168 } // namespace ranges
 169
 170 // [range.access.cbegin]
 171
 172 namespace ranges {
 173 namespace __cbegin {
 174   struct __fn {
 175     template <class _Tp>
 176       requires is_lvalue_reference_v<_Tp&&>
 177     [[nodiscard]] _LIBCPP_HIDE_FROM_ABI
 178     constexpr auto operator()(_Tp&& __t) const
 179       noexcept(noexcept(ranges::begin(static_cast<const remove_reference_t<_Tp>&>(__t))))
 180       -> decltype(      ranges::begin(static_cast<const remove_reference_t<_Tp>&>(__t)))
 181       { return          ranges::begin(static_cast<const remove_reference_t<_Tp>&>(__t)); }
 182
 183     template <class _Tp>
 184       requires is_rvalue_reference_v<_Tp&&>
 185     [[nodiscard]] _LIBCPP_HIDE_FROM_ABI
 186     constexpr auto operator()(_Tp&& __t) const
 187       noexcept(noexcept(ranges::begin(static_cast<const _Tp&&>(__t))))
 188       -> decltype(      ranges::begin(static_cast<const _Tp&&>(__t)))
 189       { return          ranges::begin(static_cast<const _Tp&&>(__t)); }
 190   };
 191 } // namespace __cbegin
 192
 193 inline namespace __cpo {
 194   inline constexpr auto cbegin = __cbegin::__fn{};
 195 } // namespace __cpo
 196 } // namespace ranges
 197
 198 // [range.access.cend]
 199
 200 namespace ranges {
 201 namespace __cend {
 202   struct __fn {
 203     template <class _Tp>
 204       requires is_lvalue_reference_v<_Tp&&>
 205     [[nodiscard]] _LIBCPP_HIDE_FROM_ABI
 206     constexpr auto operator()(_Tp&& __t) const
 207       noexcept(noexcept(ranges::end(static_cast<const remove_reference_t<_Tp>&>(__t))))
 208       -> decltype(      ranges::end(static_cast<const remove_reference_t<_Tp>&>(__t)))
 209       { return          ranges::end(static_cast<const remove_reference_t<_Tp>&>(__t)); }
 210
 211     template <class _Tp>
 212       requires is_rvalue_reference_v<_Tp&&>
 213     [[nodiscard]] _LIBCPP_HIDE_FROM_ABI
 214     constexpr auto operator()(_Tp&& __t) const
 215       noexcept(noexcept(ranges::end(static_cast<const _Tp&&>(__t))))
 216       -> decltype(      ranges::end(static_cast<const _Tp&&>(__t)))
 217       { return          ranges::end(static_cast<const _Tp&&>(__t)); }
 218   };
 219 } // namespace __cend
 220
 221 inline namespace __cpo {
 222   inline constexpr auto cend = __cend::__fn{};
 223 } // namespace __cpo
 224 } // namespace ranges
 225
 226 #endif // _LIBCPP_STD_VER >= 20
 227
 228 _LIBCPP_END_NAMESPACE_STD
 229
 230 #endif // _LIBCPP___RANGES_ACCESS_H