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005916de58
Instead of using `reverse_iterator`, share the optimization between the 4 algorithms. The key observation here that `memmove` applies to both `copy` and `move` identically, and to their `_backward` versions very similarly. All algorithms now follow the same pattern along the lines of:
```
if constexpr (can_memmove<InIter, OutIter>) {
memmove(first, last, out);
} else {
naive_implementation(first, last, out);
}
```
A follow-up will delete `unconstrained_reverse_iterator`.
This patch removes duplication and divergence between `std::copy`, `std::move` and `std::move_backward`. It also improves testing:
- the test for whether the optimization is used only applied to `std::copy` and, more importantly, was essentially a no-op because it would still pass if the optimization was not used;
- there were no tests to make sure the optimization is not used when the effect would be visible.
Differential Revision: https://reviews.llvm.org/D130695
82 lines
2.8 KiB
C++
82 lines
2.8 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___ALGORITHM_SET_DIFFERENCE_H
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#define _LIBCPP___ALGORITHM_SET_DIFFERENCE_H
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#include <__algorithm/comp.h>
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#include <__algorithm/comp_ref_type.h>
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#include <__algorithm/copy.h>
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#include <__algorithm/iterator_operations.h>
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#include <__config>
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#include <__functional/identity.h>
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#include <__functional/invoke.h>
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#include <__iterator/iterator_traits.h>
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#include <__utility/move.h>
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#include <__utility/pair.h>
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#include <type_traits>
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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_BEGIN_NAMESPACE_STD
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template <class _AlgPolicy, class _Comp, class _InIter1, class _Sent1, class _InIter2, class _Sent2, class _OutIter>
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_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<__remove_cvref_t<_InIter1>, __remove_cvref_t<_OutIter> >
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__set_difference(
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_InIter1&& __first1, _Sent1&& __last1, _InIter2&& __first2, _Sent2&& __last2, _OutIter&& __result, _Comp&& __comp) {
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while (__first1 != __last1 && __first2 != __last2) {
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if (__comp(*__first1, *__first2)) {
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*__result = *__first1;
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++__first1;
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++__result;
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} else if (__comp(*__first2, *__first1)) {
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++__first2;
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} else {
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++__first1;
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++__first2;
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}
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}
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return std::__copy<_AlgPolicy>(std::move(__first1), std::move(__last1), std::move(__result));
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}
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template <class _InputIterator1, class _InputIterator2, class _OutputIterator, class _Compare>
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inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _OutputIterator set_difference(
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_InputIterator1 __first1,
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_InputIterator1 __last1,
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_InputIterator2 __first2,
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_InputIterator2 __last2,
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_OutputIterator __result,
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_Compare __comp) {
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return std::__set_difference<_ClassicAlgPolicy, __comp_ref_type<_Compare> >(
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__first1, __last1, __first2, __last2, __result, __comp)
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.second;
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}
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template <class _InputIterator1, class _InputIterator2, class _OutputIterator>
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inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _OutputIterator set_difference(
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_InputIterator1 __first1,
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_InputIterator1 __last1,
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_InputIterator2 __first2,
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_InputIterator2 __last2,
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_OutputIterator __result) {
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return std::__set_difference<_ClassicAlgPolicy>(
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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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__less<typename iterator_traits<_InputIterator1>::value_type,
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typename iterator_traits<_InputIterator2>::value_type>()).second;
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}
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___ALGORITHM_SET_DIFFERENCE_H
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