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https://github.com/jart/cosmopolitan.git
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85 lines
3.1 KiB
C++
85 lines
3.1 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___PSTL_CPU_ALGOS_MERGE_H
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#define _LIBCPP___PSTL_CPU_ALGOS_MERGE_H
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#include <__algorithm/merge.h>
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#include <__assert>
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#include <__config>
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#include <__iterator/concepts.h>
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#include <__pstl/backend_fwd.h>
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#include <__pstl/cpu_algos/cpu_traits.h>
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#include <__type_traits/is_execution_policy.h>
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#include <__utility/move.h>
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#include <optional>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_PUSH_MACROS
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#include <__undef_macros>
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_LIBCPP_BEGIN_NAMESPACE_STD
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namespace __pstl {
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template <class _Backend, class _RawExecutionPolicy>
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struct __cpu_parallel_merge {
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template <class _Policy, class _ForwardIterator1, class _ForwardIterator2, class _ForwardOutIterator, class _Comp>
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_LIBCPP_HIDE_FROM_ABI optional<_ForwardOutIterator> operator()(
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_Policy&& __policy,
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_ForwardIterator1 __first1,
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_ForwardIterator1 __last1,
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_ForwardIterator2 __first2,
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_ForwardIterator2 __last2,
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_ForwardOutIterator __result,
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_Comp __comp) const noexcept {
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if constexpr (__is_parallel_execution_policy_v<_RawExecutionPolicy> &&
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__has_random_access_iterator_category_or_concept<_ForwardIterator1>::value &&
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__has_random_access_iterator_category_or_concept<_ForwardIterator2>::value &&
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__has_random_access_iterator_category_or_concept<_ForwardOutIterator>::value) {
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auto __res = __cpu_traits<_Backend>::__merge(
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__first1,
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__last1,
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__first2,
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__last2,
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__result,
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__comp,
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[&__policy](_ForwardIterator1 __g_first1,
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_ForwardIterator1 __g_last1,
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_ForwardIterator2 __g_first2,
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_ForwardIterator2 __g_last2,
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_ForwardOutIterator __g_result,
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_Comp __g_comp) {
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using _MergeUnseq = __pstl::__merge<_Backend, __remove_parallel_policy_t<_RawExecutionPolicy>>;
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[[maybe_unused]] auto __g_res = _MergeUnseq()(
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std::__remove_parallel_policy(__policy),
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std::move(__g_first1),
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std::move(__g_last1),
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std::move(__g_first2),
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std::move(__g_last2),
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std::move(__g_result),
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std::move(__g_comp));
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_LIBCPP_ASSERT_INTERNAL(__g_res, "unsed/sed should never try to allocate!");
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});
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if (!__res)
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return nullopt;
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return __result + (__last1 - __first1) + (__last2 - __first2);
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} else {
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return std::merge(__first1, __last1, __first2, __last2, __result, __comp);
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}
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}
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};
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} // namespace __pstl
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___PSTL_CPU_ALGOS_MERGE_H
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