libcxx/include/__cxx03/__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___CXX03___RANGES_ACCESS_H
  11 #define _LIBCPP___CXX03___RANGES_ACCESS_H
  12
  13 #include <__cxx03/__concepts/class_or_enum.h>
  14 #include <__cxx03/__config>
  15 #include <__cxx03/__iterator/concepts.h>
  16 #include <__cxx03/__iterator/readable_traits.h>
  17 #include <__cxx03/__ranges/enable_borrowed_range.h>
  18 #include <__cxx03/__type_traits/decay.h>
  19 #include <__cxx03/__type_traits/is_reference.h>
  20 #include <__cxx03/__type_traits/remove_cvref.h>
  21 #include <__cxx03/__type_traits/remove_reference.h>
  22 #include <__cxx03/__utility/auto_cast.h>
  23 #include <__cxx03/__utility/declval.h>
  24 #include <__cxx03/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 = is_lvalue_reference_v<_Tp> || enable_borrowed_range<remove_cvref_t<_Tp>>;
  37 } // namespace ranges
  38
  39 // [range.access.begin]
  40
  41 namespace ranges {
  42 namespace __begin {
  43 template <class _Tp>
  44 concept __member_begin = __can_borrow<_Tp> && requires(_Tp&& __t) {
  45   { _LIBCPP_AUTO_CAST(__t.begin()) } -> input_or_output_iterator;
  46 };
  47
  48 void begin() = delete;
  49
  50 template <class _Tp>
  51 concept __unqualified_begin =
  52     !__member_begin<_Tp> && __can_borrow<_Tp> && __class_or_enum<remove_cvref_t<_Tp>> && requires(_Tp&& __t) {
  53       { _LIBCPP_AUTO_CAST(begin(__t)) } -> input_or_output_iterator;
  54     };
  55
  56 struct __fn {
  57   template <class _Tp>
  58   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp (&__t)[]) const noexcept
  59     requires(sizeof(_Tp) >= 0) // Disallow incomplete element types.
  60   {
  61     return __t + 0;
  62   }
  63
  64   template <class _Tp, size_t _Np>
  65   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp (&__t)[_Np]) const noexcept
  66     requires(sizeof(_Tp) >= 0) // Disallow incomplete element types.
  67   {
  68     return __t + 0;
  69   }
  70
  71   template <class _Tp>
  72     requires __member_begin<_Tp>
  73   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
  74       noexcept(noexcept(_LIBCPP_AUTO_CAST(__t.begin()))) {
  75     return _LIBCPP_AUTO_CAST(__t.begin());
  76   }
  77
  78   template <class _Tp>
  79     requires __unqualified_begin<_Tp>
  80   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
  81       noexcept(noexcept(_LIBCPP_AUTO_CAST(begin(__t)))) {
  82     return _LIBCPP_AUTO_CAST(begin(__t));
  83   }
  84
  85   void operator()(auto&&) const = delete;
  86 };
  87 } // namespace __begin
  88
  89 inline namespace __cpo {
  90 inline constexpr auto begin = __begin::__fn{};
  91 } // namespace __cpo
  92 } // namespace ranges
  93
  94 // [range.range]
  95
  96 namespace ranges {
  97 template <class _Tp>
  98 using iterator_t = decltype(ranges::begin(std::declval<_Tp&>()));
  99 } // namespace ranges
 100
 101 // [range.access.end]
 102
 103 namespace ranges {
 104 namespace __end {
 105 template <class _Tp>
 106 concept __member_end = __can_borrow<_Tp> && requires(_Tp&& __t) {
 107   typename iterator_t<_Tp>;
 108   { _LIBCPP_AUTO_CAST(__t.end()) } -> sentinel_for<iterator_t<_Tp>>;
 109 };
 110
 111 void end() = delete;
 112
 113 template <class _Tp>
 114 concept __unqualified_end =
 115     !__member_end<_Tp> && __can_borrow<_Tp> && __class_or_enum<remove_cvref_t<_Tp>> && requires(_Tp&& __t) {
 116       typename iterator_t<_Tp>;
 117       { _LIBCPP_AUTO_CAST(end(__t)) } -> sentinel_for<iterator_t<_Tp>>;
 118     };
 119
 120 struct __fn {
 121   template <class _Tp, size_t _Np>
 122   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp (&__t)[_Np]) const noexcept
 123     requires(sizeof(_Tp) >= 0) // Disallow incomplete element types.
 124   {
 125     return __t + _Np;
 126   }
 127
 128   template <class _Tp>
 129     requires __member_end<_Tp>
 130   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
 131       noexcept(noexcept(_LIBCPP_AUTO_CAST(__t.end()))) {
 132     return _LIBCPP_AUTO_CAST(__t.end());
 133   }
 134
 135   template <class _Tp>
 136     requires __unqualified_end<_Tp>
 137   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
 138       noexcept(noexcept(_LIBCPP_AUTO_CAST(end(__t)))) {
 139     return _LIBCPP_AUTO_CAST(end(__t));
 140   }
 141
 142   void operator()(auto&&) const = delete;
 143 };
 144 } // namespace __end
 145
 146 inline namespace __cpo {
 147 inline constexpr auto end = __end::__fn{};
 148 } // namespace __cpo
 149 } // namespace ranges
 150
 151 // [range.access.cbegin]
 152
 153 namespace ranges {
 154 namespace __cbegin {
 155 struct __fn {
 156   template <class _Tp>
 157     requires is_lvalue_reference_v<_Tp&&>
 158   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
 159       noexcept(noexcept(ranges::begin(static_cast<const remove_reference_t<_Tp>&>(__t))))
 160           -> decltype(ranges::begin(static_cast<const remove_reference_t<_Tp>&>(__t))) {
 161     return ranges::begin(static_cast<const remove_reference_t<_Tp>&>(__t));
 162   }
 163
 164   template <class _Tp>
 165     requires is_rvalue_reference_v<_Tp&&>
 166   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
 167       noexcept(noexcept(ranges::begin(static_cast<const _Tp&&>(__t))))
 168           -> decltype(ranges::begin(static_cast<const _Tp&&>(__t))) {
 169     return ranges::begin(static_cast<const _Tp&&>(__t));
 170   }
 171 };
 172 } // namespace __cbegin
 173
 174 inline namespace __cpo {
 175 inline constexpr auto cbegin = __cbegin::__fn{};
 176 } // namespace __cpo
 177 } // namespace ranges
 178
 179 // [range.access.cend]
 180
 181 namespace ranges {
 182 namespace __cend {
 183 struct __fn {
 184   template <class _Tp>
 185     requires is_lvalue_reference_v<_Tp&&>
 186   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const
 187       noexcept(noexcept(ranges::end(static_cast<const remove_reference_t<_Tp>&>(__t))))
 188           -> decltype(ranges::end(static_cast<const remove_reference_t<_Tp>&>(__t))) {
 189     return ranges::end(static_cast<const remove_reference_t<_Tp>&>(__t));
 190   }
 191
 192   template <class _Tp>
 193     requires is_rvalue_reference_v<_Tp&&>
 194   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Tp&& __t) const noexcept(
 195       noexcept(ranges::end(static_cast<const _Tp&&>(__t)))) -> decltype(ranges::end(static_cast<const _Tp&&>(__t))) {
 196     return ranges::end(static_cast<const _Tp&&>(__t));
 197   }
 198 };
 199 } // namespace __cend
 200
 201 inline namespace __cpo {
 202 inline constexpr auto cend = __cend::__fn{};
 203 } // namespace __cpo
 204 } // namespace ranges
 205
 206 #endif // _LIBCPP_STD_VER >= 20
 207
 208 _LIBCPP_END_NAMESPACE_STD
 209
 210 #endif // _LIBCPP___CXX03___RANGES_ACCESS_H