libcxx/include/__cxx03/__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 <__cxx03/__config>
  13 #include <__cxx03/__iterator/concepts.h>
  14 #include <__cxx03/__iterator/iterator_traits.h>
  15 #include <__cxx03/__type_traits/remove_cvref.h>
  16
  17 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  18 #  pragma GCC system_header
  19 #endif
  20
  21 _LIBCPP_PUSH_MACROS
  22 #include <__cxx03/__undef_macros>
  23
  24 #if _LIBCPP_STD_VER >= 20
  25
  26 _LIBCPP_BEGIN_NAMESPACE_STD
  27
  28 namespace ranges {
  29
  30 template <class _IterMaybeQualified>
  31 consteval auto __get_iterator_concept() {
  32   using _Iter = __remove_cvref_t<_IterMaybeQualified>;
  33
  34   if constexpr (contiguous_iterator<_Iter>)
  35     return contiguous_iterator_tag();
  36   else if constexpr (random_access_iterator<_Iter>)
  37     return random_access_iterator_tag();
  38   else if constexpr (bidirectional_iterator<_Iter>)
  39     return bidirectional_iterator_tag();
  40   else if constexpr (forward_iterator<_Iter>)
  41     return forward_iterator_tag();
  42   else if constexpr (input_iterator<_Iter>)
  43     return input_iterator_tag();
  44 }
  45
  46 template <class _Iter>
  47 using __iterator_concept = decltype(__get_iterator_concept<_Iter>());
  48
  49 } // namespace ranges
  50 _LIBCPP_END_NAMESPACE_STD
  51
  52 #endif // _LIBCPP_STD_VER >= 20
  53
  54 _LIBCPP_POP_MACROS
  55
  56 #endif // _LIBCPP___ALGORITHM_RANGES_ITERATOR_CONCEPT_H