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___PSTL_CPU_ALGOS_MERGE_H 10 #define _LIBCPP___PSTL_CPU_ALGOS_MERGE_H 11 12 #include <__algorithm/merge.h> 13 #include <__assert> 14 #include <__config> 15 #include <__iterator/concepts.h> 16 #include <__pstl/backend_fwd.h> 17 #include <__pstl/cpu_algos/cpu_traits.h> 18 #include <__type_traits/is_execution_policy.h> 19 #include <__utility/move.h> 20 #include <optional> 21 22 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 23 # pragma GCC system_header 24 #endif 25 26 _LIBCPP_PUSH_MACROS 27 #include <__undef_macros> 28 29 #if _LIBCPP_STD_VER >= 17 30 31 _LIBCPP_BEGIN_NAMESPACE_STD 32 namespace __pstl { 33 34 template <class _Backend, class _RawExecutionPolicy> 35 struct __cpu_parallel_merge { 36 template <class _Policy, class _ForwardIterator1, class _ForwardIterator2, class _ForwardOutIterator, class _Comp> 37 _LIBCPP_HIDE_FROM_ABI optional<_ForwardOutIterator> operator()( 38 _Policy&& __policy, 39 _ForwardIterator1 __first1, 40 _ForwardIterator1 __last1, 41 _ForwardIterator2 __first2, 42 _ForwardIterator2 __last2, 43 _ForwardOutIterator __result, 44 _Comp __comp) const noexcept { 45 if constexpr (__is_parallel_execution_policy_v<_RawExecutionPolicy> && 46 __has_random_access_iterator_category_or_concept<_ForwardIterator1>::value && 47 __has_random_access_iterator_category_or_concept<_ForwardIterator2>::value && 48 __has_random_access_iterator_category_or_concept<_ForwardOutIterator>::value) { 49 auto __res = __cpu_traits<_Backend>::__merge( 50 __first1, 51 __last1, 52 __first2, 53 __last2, 54 __result, 55 __comp, 56 [&__policy](_ForwardIterator1 __g_first1, 57 _ForwardIterator1 __g_last1, 58 _ForwardIterator2 __g_first2, 59 _ForwardIterator2 __g_last2, 60 _ForwardOutIterator __g_result, 61 _Comp __g_comp) { 62 using _MergeUnseq = __pstl::__merge<_Backend, __remove_parallel_policy_t<_RawExecutionPolicy>>; 63 [[maybe_unused]] auto __g_res = _MergeUnseq()( 64 std::__remove_parallel_policy(__policy), 65 std::move(__g_first1), 66 std::move(__g_last1), 67 std::move(__g_first2), 68 std::move(__g_last2), 69 std::move(__g_result), 70 std::move(__g_comp)); 71 _LIBCPP_ASSERT_INTERNAL(__g_res, "unsed/sed should never try to allocate!"); 72 }); 73 if (!__res) 74 return nullopt; 75 return __result + (__last1 - __first1) + (__last2 - __first2); 76 } else { 77 return std::merge(__first1, __last1, __first2, __last2, __result, __comp); 78 } 79 } 80 }; 81 82 } // namespace __pstl 83 _LIBCPP_END_NAMESPACE_STD 84 85 #endif // _LIBCPP_STD_VER >= 17 86 87 _LIBCPP_POP_MACROS 88 89 #endif // _LIBCPP___PSTL_CPU_ALGOS_MERGE_H 90