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___ALGORITHM_PSTL_BACKENDS_CPU_BACKENDS_MERGE_H
10 #define _LIBCPP___ALGORITHM_PSTL_BACKENDS_CPU_BACKENDS_MERGE_H
11
12 #include <__algorithm/merge.h>
13 #include <__algorithm/pstl_backends/cpu_backends/backend.h>
14 #include <__config>
15 #include <__iterator/concepts.h>
16 #include <__type_traits/is_execution_policy.h>
17 #include <__utility/move.h>
18 #include <optional>
19
20 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
21 # pragma GCC system_header
22 #endif
23
24 #if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
25
26 _LIBCPP_PUSH_MACROS
27 # include <__undef_macros>
28
29 _LIBCPP_BEGIN_NAMESPACE_STD
30
31 template <class _ExecutionPolicy,
32 class _ForwardIterator1,
33 class _ForwardIterator2,
34 class _ForwardOutIterator,
35 class _Comp>
__pstl_merge(__cpu_backend_tag,_ForwardIterator1 __first1,_ForwardIterator1 __last1,_ForwardIterator2 __first2,_ForwardIterator2 __last2,_ForwardOutIterator __result,_Comp __comp)36 _LIBCPP_HIDE_FROM_ABI optional<_ForwardOutIterator> __pstl_merge(
37 __cpu_backend_tag,
38 _ForwardIterator1 __first1,
39 _ForwardIterator1 __last1,
40 _ForwardIterator2 __first2,
41 _ForwardIterator2 __last2,
42 _ForwardOutIterator __result,
43 _Comp __comp) {
44 if constexpr (__is_parallel_execution_policy_v<_ExecutionPolicy> &&
45 __has_random_access_iterator_category_or_concept<_ForwardIterator1>::value &&
46 __has_random_access_iterator_category_or_concept<_ForwardIterator2>::value &&
47 __has_random_access_iterator_category_or_concept<_ForwardOutIterator>::value) {
48 auto __res = __par_backend::__parallel_merge(
49 __first1,
50 __last1,
51 __first2,
52 __last2,
53 __result,
54 __comp,
55 [](_ForwardIterator1 __g_first1,
56 _ForwardIterator1 __g_last1,
57 _ForwardIterator2 __g_first2,
58 _ForwardIterator2 __g_last2,
59 _ForwardOutIterator __g_result,
60 _Comp __g_comp) {
61 [[maybe_unused]] auto __g_res = std::__pstl_merge<__remove_parallel_policy_t<_ExecutionPolicy>>(
62 __cpu_backend_tag{},
63 std::move(__g_first1),
64 std::move(__g_last1),
65 std::move(__g_first2),
66 std::move(__g_last2),
67 std::move(__g_result),
68 std::move(__g_comp));
69 _LIBCPP_ASSERT_INTERNAL(__g_res, "unsed/sed should never try to allocate!");
70 });
71 if (!__res)
72 return nullopt;
73 return __result + (__last1 - __first1) + (__last2 - __first2);
74 } else {
75 return std::merge(__first1, __last1, __first2, __last2, __result, __comp);
76 }
77 }
78
79 _LIBCPP_END_NAMESPACE_STD
80
81 _LIBCPP_POP_MACROS
82
83 #endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
84
85 #endif // _LIBCPP___ALGORITHM_PSTL_BACKENDS_CPU_BACKENDS_MERGE_H
86