1 // -*- C++ -*-
2 //===----------------------------------------------------------------------===//
3 //
4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5 // See https://llvm.org/LICENSE.txt for license information.
6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #ifndef _LIBCPP___RANGES_DANGLING_H
11 #define _LIBCPP___RANGES_DANGLING_H
12 
13 #include <__config>
14 #include <__ranges/access.h>
15 #include <__ranges/concepts.h>
16 #include <type_traits>
17 
18 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
19 #pragma GCC system_header
20 #endif
21 
22 _LIBCPP_PUSH_MACROS
23 #include <__undef_macros>
24 
25 _LIBCPP_BEGIN_NAMESPACE_STD
26 
27 #if !defined(_LIBCPP_HAS_NO_RANGES)
28 
29 namespace ranges {
30 struct dangling {
31   dangling() = default;
32   _LIBCPP_HIDE_FROM_ABI constexpr dangling(auto&&...) noexcept {}
33 };
34 
35 template <range _Rp>
36 using borrowed_iterator_t = _If<borrowed_range<_Rp>, iterator_t<_Rp>, dangling>;
37 
38 // borrowed_subrange_t defined in <__ranges/subrange.h>
39 } // namespace ranges
40 
41 #endif // !_LIBCPP_HAS_NO_RANGES
42 
43 _LIBCPP_END_NAMESPACE_STD
44 
45 _LIBCPP_POP_MACROS
46 
47 #endif // _LIBCPP___RANGES_DANGLING_H
48