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 _LIBCPP_BEGIN_NAMESPACE_STD 30 namespace __pstl { 31 32 template <class _Backend, class _RawExecutionPolicy> 33 struct __cpu_parallel_merge { 34 template <class _Policy, class _ForwardIterator1, class _ForwardIterator2, class _ForwardOutIterator, class _Comp> 35 _LIBCPP_HIDE_FROM_ABI optional<_ForwardOutIterator> operator()( 36 _Policy&& __policy, 37 _ForwardIterator1 __first1, 38 _ForwardIterator1 __last1, 39 _ForwardIterator2 __first2, 40 _ForwardIterator2 __last2, 41 _ForwardOutIterator __result, 42 _Comp __comp) const noexcept { 43 if constexpr (__is_parallel_execution_policy_v<_RawExecutionPolicy> && 44 __has_random_access_iterator_category_or_concept<_ForwardIterator1>::value && 45 __has_random_access_iterator_category_or_concept<_ForwardIterator2>::value && 46 __has_random_access_iterator_category_or_concept<_ForwardOutIterator>::value) { 47 auto __res = __cpu_traits<_Backend>::__merge( 48 __first1, 49 __last1, 50 __first2, 51 __last2, 52 __result, 53 __comp, 54 [&__policy](_ForwardIterator1 __g_first1, 55 _ForwardIterator1 __g_last1, 56 _ForwardIterator2 __g_first2, 57 _ForwardIterator2 __g_last2, 58 _ForwardOutIterator __g_result, 59 _Comp __g_comp) { 60 using _MergeUnseq = __pstl::__merge<_Backend, __remove_parallel_policy_t<_RawExecutionPolicy>>; 61 [[maybe_unused]] auto __g_res = _MergeUnseq()( 62 std::__remove_parallel_policy(__policy), 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 80 } // namespace __pstl 81 _LIBCPP_END_NAMESPACE_STD 82 83 _LIBCPP_POP_MACROS 84 85 #endif // _LIBCPP___PSTL_CPU_ALGOS_MERGE_H 86