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 > 17
26 
27 template <class _Input1, class _Input2, class _Output,
28           class _Comp = ranges::less, class _Proj1 = identity, class _Proj2 = identity>
29 concept mergeable =
30     input_iterator<_Input1> &&
31     input_iterator<_Input2> &&
32     weakly_incrementable<_Output> &&
33     indirectly_copyable<_Input1, _Output> &&
34     indirectly_copyable<_Input2, _Output> &&
35     indirect_strict_weak_order<_Comp, projected<_Input1, _Proj1>, projected<_Input2, _Proj2>>;
36 
37 #endif // _LIBCPP_STD_VER > 17
38 
39 _LIBCPP_END_NAMESPACE_STD
40 
41 #endif // _LIBCPP___ITERATOR_MERGEABLE_H
42