libcxx/include/__tuple/tuple_like.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___TUPLE_TUPLE_LIKE_H
  10 #define _LIBCPP___TUPLE_TUPLE_LIKE_H
  11
  12 #include <__config>
  13 #include <__fwd/array.h>
  14 #include <__fwd/pair.h>
  15 #include <__fwd/subrange.h>
  16 #include <__fwd/tuple.h>
  17 #include <__type_traits/integral_constant.h>
  18 #include <__type_traits/remove_cvref.h>
  19 #include <cstddef>
  20
  21 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  22 #  pragma GCC system_header
  23 #endif
  24
  25 _LIBCPP_BEGIN_NAMESPACE_STD
  26
  27 #if _LIBCPP_STD_VER >= 20
  28
  29 template <class _Tp>
  30 struct __tuple_like_impl : false_type {};
  31
  32 template <class... _Tp>
  33 struct __tuple_like_impl<tuple<_Tp...> > : true_type {};
  34
  35 template <class _T1, class _T2>
  36 struct __tuple_like_impl<pair<_T1, _T2> > : true_type {};
  37
  38 template <class _Tp, size_t _Size>
  39 struct __tuple_like_impl<array<_Tp, _Size> > : true_type {};
  40
  41 template <class _Ip, class _Sp, ranges::subrange_kind _Kp>
  42 struct __tuple_like_impl<ranges::subrange<_Ip, _Sp, _Kp> > : true_type {};
  43
  44 template <class _Tp>
  45 concept __tuple_like = __tuple_like_impl<remove_cvref_t<_Tp>>::value;
  46
  47 #endif // _LIBCPP_STD_VER >= 20
  48
  49 _LIBCPP_END_NAMESPACE_STD
  50
  51 #endif // _LIBCPP___TUPLE_TUPLE_LIKE_H