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 = range<_Range> &&
  57     (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 =
  95     range<_Tp> &&
  96     movable<_Tp> &&
  97     enable_view<_Tp>;
  98
  99   template <class _Range>
 100   concept __simple_view =
 101     view<_Range> && range<const _Range> &&
 102     same_as<iterator_t<_Range>, iterator_t<const _Range>> &&
 103     same_as<sentinel_t<_Range>, sentinel_t<const _Range>>;
 104
 105   // [range.refinements], other range refinements
 106   template <class _Rp, class _Tp>
 107   concept output_range = range<_Rp> && output_iterator<iterator_t<_Rp>, _Tp>;
 108
 109   template <class _Tp>
 110   concept forward_range = input_range<_Tp> && forward_iterator<iterator_t<_Tp>>;
 111
 112   template <class _Tp>
 113   concept bidirectional_range = forward_range<_Tp> && bidirectional_iterator<iterator_t<_Tp>>;
 114
 115   template <class _Tp>
 116   concept random_access_range =
 117       bidirectional_range<_Tp> && random_access_iterator<iterator_t<_Tp>>;
 118
 119   template<class _Tp>
 120   concept contiguous_range =
 121     random_access_range<_Tp> &&
 122     contiguous_iterator<iterator_t<_Tp>> &&
 123     requires(_Tp& __t) {
 124       { ranges::data(__t) } -> same_as<add_pointer_t<range_reference_t<_Tp>>>;
 125     };
 126
 127   template <class _Tp>
 128   concept common_range = range<_Tp> && same_as<iterator_t<_Tp>, sentinel_t<_Tp>>;
 129
 130   template <class _Tp>
 131   inline constexpr bool __is_std_initializer_list = false;
 132
 133   template <class _Ep>
 134   inline constexpr bool __is_std_initializer_list<initializer_list<_Ep>> = true;
 135
 136   template <class _Tp>
 137   concept viewable_range =
 138     range<_Tp> &&
 139     ((view<remove_cvref_t<_Tp>> && constructible_from<remove_cvref_t<_Tp>, _Tp>) ||
 140      (!view<remove_cvref_t<_Tp>> &&
 141       (is_lvalue_reference_v<_Tp> ||
 142        (movable<remove_reference_t<_Tp>> && !__is_std_initializer_list<remove_cvref_t<_Tp>>))));
 143
 144 } // namespace ranges
 145
 146 #endif // _LIBCPP_STD_VER >= 20
 147
 148 _LIBCPP_END_NAMESPACE_STD
 149
 150 #endif // _LIBCPP___RANGES_CONCEPTS_H