libcxx/include/__tuple/tuple_like_no_subrange.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_NO_SUBRANGE_H
  10 #define _LIBCPP___TUPLE_TUPLE_LIKE_NO_SUBRANGE_H
  11
  12 #include <__config>
  13 #include <__cstddef/size_t.h>
  14 #include <__fwd/array.h>
  15 #include <__fwd/complex.h>
  16 #include <__fwd/pair.h>
  17 #include <__fwd/tuple.h>
  18 #include <__tuple/tuple_size.h>
  19 #include <__type_traits/remove_cvref.h>
  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 inline constexpr bool __tuple_like_no_subrange_impl = false;
  31
  32 template <class... _Tp>
  33 inline constexpr bool __tuple_like_no_subrange_impl<tuple<_Tp...>> = true;
  34
  35 template <class _T1, class _T2>
  36 inline constexpr bool __tuple_like_no_subrange_impl<pair<_T1, _T2>> = true;
  37
  38 template <class _Tp, size_t _Size>
  39 inline constexpr bool __tuple_like_no_subrange_impl<array<_Tp, _Size>> = true;
  40
  41 #  if _LIBCPP_STD_VER >= 26
  42
  43 template <class _Tp>
  44 inline constexpr bool __tuple_like_no_subrange_impl<complex<_Tp>> = true;
  45
  46 #  endif
  47
  48 template <class _Tp>
  49 concept __tuple_like_no_subrange = __tuple_like_no_subrange_impl<remove_cvref_t<_Tp>>;
  50
  51 // This is equivalent to the exposition-only type trait `pair-like`, except that it is false for specializations of
  52 // `ranges::subrange`. This is more useful than the pair-like concept in the standard because every use of `pair-like`
  53 // excludes `ranges::subrange`.
  54 template <class _Tp>
  55 concept __pair_like_no_subrange = __tuple_like_no_subrange<_Tp> && tuple_size<remove_cvref_t<_Tp>>::value == 2;
  56
  57 #endif // _LIBCPP_STD_VER >= 20
  58
  59 _LIBCPP_END_NAMESPACE_STD
  60
  61 #endif // _LIBCPP___TUPLE_TUPLE_LIKE_NO_SUBRANGE_H