__cxx03/__ranges/dangling.h

0001 // -*- C++ -*-
0002 //===----------------------------------------------------------------------===//
0003 //
0004 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0005 // See https://llvm.org/LICENSE.txt for license information.
0006 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0007 //
0008 //===----------------------------------------------------------------------===//
0009
0010 #ifndef _LIBCPP___CXX03___RANGES_DANGLING_H
0011 #define _LIBCPP___CXX03___RANGES_DANGLING_H
0012
0013 #include <__cxx03/__config>
0014 #include <__cxx03/__ranges/access.h>
0015 #include <__cxx03/__ranges/concepts.h>
0016 #include <__cxx03/__type_traits/conditional.h>
0017
0018 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0019 #  pragma GCC system_header
0020 #endif
0021
0022 _LIBCPP_BEGIN_NAMESPACE_STD
0023
0024 #if _LIBCPP_STD_VER >= 20
0025
0026 namespace ranges {
0027 struct dangling {
0028   dangling() = default;
0029   _LIBCPP_HIDE_FROM_ABI constexpr dangling(auto&&...) noexcept {}
0030 };
0031
0032 template <range _Rp>
0033 using borrowed_iterator_t = _If<borrowed_range<_Rp>, iterator_t<_Rp>, dangling>;
0034
0035 // borrowed_subrange_t defined in <__ranges/subrange.h>
0036 } // namespace ranges
0037
0038 #endif // _LIBCPP_STD_VER >= 20
0039
0040 _LIBCPP_END_NAMESPACE_STD
0041
0042 #endif // _LIBCPP___CXX03___RANGES_DANGLING_H