fc5e0c071b
This patch does two things. (1) It replaces SFINAE with `if constexpr`, avoiding some overload resolution and unnecessary boilerplate. (2) It removes an overload from `__for_each_n` to forward to `__for_each`, since `__for_each` doesn't provide any further optimizations.
76 lines
2.4 KiB
C++
76 lines
2.4 KiB
C++
// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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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___ALGORITHM_FOR_EACH_N_H
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#define _LIBCPP___ALGORITHM_FOR_EACH_N_H
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#include <__algorithm/for_each.h>
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#include <__algorithm/for_each_n_segment.h>
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#include <__config>
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#include <__functional/identity.h>
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#include <__iterator/iterator_traits.h>
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#include <__iterator/segmented_iterator.h>
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#include <__type_traits/invoke.h>
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#include <__utility/convert_to_integral.h>
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#include <__utility/move.h>
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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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template <class _InputIterator, class _Size, class _Func, class _Proj>
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_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _InputIterator
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__for_each_n(_InputIterator __first, _Size __orig_n, _Func& __f, _Proj& __proj) {
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typedef decltype(std::__convert_to_integral(__orig_n)) _IntegralSize;
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_IntegralSize __n = __orig_n;
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#ifndef _LIBCPP_CXX03_LANG
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if constexpr (__is_segmented_iterator_v<_InputIterator>) {
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using __local_iterator = typename __segmented_iterator_traits<_InputIterator>::__local_iterator;
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if constexpr (__has_random_access_iterator_category<__local_iterator>::value) {
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return std::__for_each_n_segment(__first, __orig_n, [&](__local_iterator __lfirst, __local_iterator __llast) {
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std::__for_each(__lfirst, __llast, __f, __proj);
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});
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} else {
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return std::__for_each(__first, __first + __n, __f, __proj);
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}
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} else
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#endif
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{
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while (__n > 0) {
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std::__invoke(__f, std::__invoke(__proj, *__first));
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++__first;
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--__n;
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}
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return std::move(__first);
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}
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}
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#if _LIBCPP_STD_VER >= 17
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template <class _InputIterator, class _Size, class _Func>
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inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _InputIterator
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for_each_n(_InputIterator __first, _Size __orig_n, _Func __f) {
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__identity __proj;
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return std::__for_each_n(__first, __orig_n, __f, __proj);
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}
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#endif // _LIBCPP_STD_VER >= 17
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___ALGORITHM_FOR_EACH_N_H
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