libcxx/include/__ranges/concepts.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_CONCEPTS_H
  11 #define _LIBCPP___RANGES_CONCEPTS_H
  12
  13 #include <__concepts/constructible.h>
  14 #include <__concepts/movable.h>
  15 #include <__concepts/same_as.h>
  16 #include <__config>
  17 #include <__iterator/concepts.h>
  18 #include <__iterator/incrementable_traits.h>
  19 #include <__iterator/iter_move.h>
  20 #include <__iterator/iterator_traits.h>
  21 #include <__iterator/readable_traits.h>
  22 #include <__ranges/access.h>
  23 #include <__ranges/data.h>
  24 #include <__ranges/enable_borrowed_range.h>
  25 #include <__ranges/enable_view.h>
  26 #include <__ranges/size.h>
  27 #include <__type_traits/add_pointer.h>
  28 #include <__type_traits/is_reference.h>
  29 #include <__type_traits/remove_cvref.h>
  30 #include <__type_traits/remove_reference.h>
  31 #include <__utility/declval.h>
  32 #include <initializer_list>
  33
  34 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  35 #  pragma GCC system_header
  36 #endif
  37
  38 _LIBCPP_BEGIN_NAMESPACE_STD
  39
  40 #if _LIBCPP_STD_VER >= 20
  41
  42 namespace ranges {
  43
  44 // [range.range]
  45
  46 template <class _Tp>
  47 concept range = requires(_Tp& __t) {
  48   ranges::begin(__t); // sometimes equality-preserving
  49   ranges::end(__t);
  50 };
  51
  52 template <class _Tp>
  53 concept input_range = range<_Tp> && input_iterator<iterator_t<_Tp>>;
  54
  55 template <class _Range>
  56 concept borrowed_range =
  57     range<_Range> && (is_lvalue_reference_v<_Range> || enable_borrowed_range<remove_cvref_t<_Range>>);
  58
  59 // `iterator_t` defined in <__ranges/access.h>
  60
  61 template <range _Rp>
  62 using sentinel_t = decltype(ranges::end(std::declval<_Rp&>()));
  63
  64 template <range _Rp>
  65 using range_difference_t = iter_difference_t<iterator_t<_Rp>>;
  66
  67 template <range _Rp>
  68 using range_value_t = iter_value_t<iterator_t<_Rp>>;
  69
  70 template <range _Rp>
  71 using range_reference_t = iter_reference_t<iterator_t<_Rp>>;
  72
  73 template <range _Rp>
  74 using range_rvalue_reference_t = iter_rvalue_reference_t<iterator_t<_Rp>>;
  75
  76 template <range _Rp>
  77 using range_common_reference_t = iter_common_reference_t<iterator_t<_Rp>>;
  78
  79 // [range.sized]
  80 template <class _Tp>
  81 concept sized_range = range<_Tp> && requires(_Tp& __t) { ranges::size(__t); };
  82
  83 template <sized_range _Rp>
  84 using range_size_t = decltype(ranges::size(std::declval<_Rp&>()));
  85
  86 // `disable_sized_range` defined in `<__ranges/size.h>`
  87
  88 // [range.view], views
  89
  90 // `enable_view` defined in <__ranges/enable_view.h>
  91 // `view_base` defined in <__ranges/enable_view.h>
  92
  93 template <class _Tp>
  94 concept view = range<_Tp> && movable<_Tp> && enable_view<_Tp>;
  95
  96 template <class _Range>
  97 concept __simple_view =
  98     view<_Range> && range<const _Range> && same_as<iterator_t<_Range>, iterator_t<const _Range>> &&
  99     same_as<sentinel_t<_Range>, sentinel_t<const _Range>>;
 100
 101 // [range.refinements], other range refinements
 102 template <class _Rp, class _Tp>
 103 concept output_range = range<_Rp> && output_iterator<iterator_t<_Rp>, _Tp>;
 104
 105 template <class _Tp>
 106 concept forward_range = input_range<_Tp> && forward_iterator<iterator_t<_Tp>>;
 107
 108 template <class _Tp>
 109 concept bidirectional_range = forward_range<_Tp> && bidirectional_iterator<iterator_t<_Tp>>;
 110
 111 template <class _Tp>
 112 concept random_access_range = bidirectional_range<_Tp> && random_access_iterator<iterator_t<_Tp>>;
 113
 114 template <class _Tp>
 115 concept contiguous_range = random_access_range<_Tp> && contiguous_iterator<iterator_t<_Tp>> && requires(_Tp& __t) {
 116   { ranges::data(__t) } -> same_as<add_pointer_t<range_reference_t<_Tp>>>;
 117 };
 118
 119 template <class _Tp>
 120 concept common_range = range<_Tp> && same_as<iterator_t<_Tp>, sentinel_t<_Tp>>;
 121
 122 template <class _Tp>
 123 inline constexpr bool __is_std_initializer_list = false;
 124
 125 template <class _Ep>
 126 inline constexpr bool __is_std_initializer_list<initializer_list<_Ep>> = true;
 127
 128 template <class _Tp>
 129 concept viewable_range =
 130     range<_Tp> &&
 131     ((view<remove_cvref_t<_Tp>> && constructible_from<remove_cvref_t<_Tp>, _Tp>) ||
 132      (!view<remove_cvref_t<_Tp>> &&
 133       (is_lvalue_reference_v<_Tp> ||
 134        (movable<remove_reference_t<_Tp>> && !__is_std_initializer_list<remove_cvref_t<_Tp>>))));
 135
 136 } // namespace ranges
 137
 138 #endif // _LIBCPP_STD_VER >= 20
 139
 140 _LIBCPP_END_NAMESPACE_STD
 141
 142 #endif // _LIBCPP___RANGES_CONCEPTS_H