libcxx/include/__algorithm/ranges_iterator_concept.h

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef _LIBCPP___ALGORITHM_RANGES_ITERATOR_CONCEPT_H
  10 #define _LIBCPP___ALGORITHM_RANGES_ITERATOR_CONCEPT_H
  11
  12 #include <__config>
  13 #include <__iterator/concepts.h>
  14 #include <__iterator/iterator_traits.h>
  15 #include <__type_traits/remove_cvref.h>
  16
  17 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  18 #  pragma GCC system_header
  19 #endif
  20
  21 #if _LIBCPP_STD_VER >= 20
  22
  23 _LIBCPP_BEGIN_NAMESPACE_STD
  24
  25 namespace ranges {
  26
  27 template <class _IterMaybeQualified>
  28 consteval auto __get_iterator_concept() {
  29   using _Iter = __remove_cvref_t<_IterMaybeQualified>;
  30
  31   if constexpr (contiguous_iterator<_Iter>)
  32     return contiguous_iterator_tag();
  33   else if constexpr (random_access_iterator<_Iter>)
  34     return random_access_iterator_tag();
  35   else if constexpr (bidirectional_iterator<_Iter>)
  36     return bidirectional_iterator_tag();
  37   else if constexpr (forward_iterator<_Iter>)
  38     return forward_iterator_tag();
  39   else if constexpr (input_iterator<_Iter>)
  40     return input_iterator_tag();
  41 }
  42
  43 template <class _Iter>
  44 using __iterator_concept = decltype(__get_iterator_concept<_Iter>());
  45
  46 } // namespace ranges
  47 _LIBCPP_END_NAMESPACE_STD
  48
  49 #endif // _LIBCPP_STD_VER >= 20
  50
  51 #endif // _LIBCPP___ALGORITHM_RANGES_ITERATOR_CONCEPT_H