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___ITERATOR_MERGEABLE_H
11 #define _LIBCPP___ITERATOR_MERGEABLE_H
12 
13 #include <__config>
14 #include <__functional/identity.h>
15 #include <__functional/ranges_operations.h>
16 #include <__iterator/concepts.h>
17 #include <__iterator/projected.h>
18 
19 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
20 #  pragma GCC system_header
21 #endif
22 
23 _LIBCPP_BEGIN_NAMESPACE_STD
24 
25 #if _LIBCPP_STD_VER >= 20
26 
27 template <class _Input1,
28           class _Input2,
29           class _Output,
30           class _Comp  = ranges::less,
31           class _Proj1 = identity,
32           class _Proj2 = identity>
33 concept mergeable =
34     input_iterator<_Input1> && input_iterator<_Input2> && weakly_incrementable<_Output> &&
35     indirectly_copyable<_Input1, _Output> && indirectly_copyable<_Input2, _Output> &&
36     indirect_strict_weak_order<_Comp, projected<_Input1, _Proj1>, projected<_Input2, _Proj2>>;
37 
38 #endif // _LIBCPP_STD_VER >= 20
39 
40 _LIBCPP_END_NAMESPACE_STD
41 
42 #endif // _LIBCPP___ITERATOR_MERGEABLE_H
43