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Diffstat (limited to 'contrib/llvm-project/libcxx/include/__algorithm/inplace_merge.h')
| -rw-r--r-- | contrib/llvm-project/libcxx/include/__algorithm/inplace_merge.h | 240 |
1 files changed, 240 insertions, 0 deletions
diff --git a/contrib/llvm-project/libcxx/include/__algorithm/inplace_merge.h b/contrib/llvm-project/libcxx/include/__algorithm/inplace_merge.h new file mode 100644 index 000000000000..eb3c0bdbc2db --- /dev/null +++ b/contrib/llvm-project/libcxx/include/__algorithm/inplace_merge.h @@ -0,0 +1,240 @@ +//===----------------------------------------------------------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// + +#ifndef _LIBCPP___ALGORITHM_INPLACE_MERGE_H +#define _LIBCPP___ALGORITHM_INPLACE_MERGE_H + +#include <__algorithm/comp.h> +#include <__algorithm/comp_ref_type.h> +#include <__algorithm/iterator_operations.h> +#include <__algorithm/lower_bound.h> +#include <__algorithm/min.h> +#include <__algorithm/move.h> +#include <__algorithm/rotate.h> +#include <__algorithm/upper_bound.h> +#include <__config> +#include <__functional/identity.h> +#include <__iterator/advance.h> +#include <__iterator/distance.h> +#include <__iterator/iterator_traits.h> +#include <__iterator/reverse_iterator.h> +#include <__memory/destruct_n.h> +#include <__memory/temporary_buffer.h> +#include <__memory/unique_ptr.h> +#include <__utility/pair.h> +#include <new> + +#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) +# pragma GCC system_header +#endif + +_LIBCPP_PUSH_MACROS +#include <__undef_macros> + +_LIBCPP_BEGIN_NAMESPACE_STD + +template <class _Predicate> +class __invert // invert the sense of a comparison +{ +private: + _Predicate __p_; + +public: + _LIBCPP_HIDE_FROM_ABI __invert() {} + + _LIBCPP_HIDE_FROM_ABI explicit __invert(_Predicate __p) : __p_(__p) {} + + template <class _T1> + _LIBCPP_HIDE_FROM_ABI bool operator()(const _T1& __x) { + return !__p_(__x); + } + + template <class _T1, class _T2> + _LIBCPP_HIDE_FROM_ABI bool operator()(const _T1& __x, const _T2& __y) { + return __p_(__y, __x); + } +}; + +template <class _AlgPolicy, + class _Compare, + class _InputIterator1, + class _Sent1, + class _InputIterator2, + class _Sent2, + class _OutputIterator> +_LIBCPP_HIDE_FROM_ABI void __half_inplace_merge( + _InputIterator1 __first1, + _Sent1 __last1, + _InputIterator2 __first2, + _Sent2 __last2, + _OutputIterator __result, + _Compare&& __comp) { + for (; __first1 != __last1; ++__result) { + if (__first2 == __last2) { + std::__move<_AlgPolicy>(__first1, __last1, __result); + return; + } + + if (__comp(*__first2, *__first1)) { + *__result = _IterOps<_AlgPolicy>::__iter_move(__first2); + ++__first2; + } else { + *__result = _IterOps<_AlgPolicy>::__iter_move(__first1); + ++__first1; + } + } + // __first2 through __last2 are already in the right spot. +} + +template <class _AlgPolicy, class _Compare, class _BidirectionalIterator> +_LIBCPP_HIDE_FROM_ABI void __buffered_inplace_merge( + _BidirectionalIterator __first, + _BidirectionalIterator __middle, + _BidirectionalIterator __last, + _Compare&& __comp, + typename iterator_traits<_BidirectionalIterator>::difference_type __len1, + typename iterator_traits<_BidirectionalIterator>::difference_type __len2, + typename iterator_traits<_BidirectionalIterator>::value_type* __buff) { + typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type; + __destruct_n __d(0); + unique_ptr<value_type, __destruct_n&> __h2(__buff, __d); + if (__len1 <= __len2) { + value_type* __p = __buff; + for (_BidirectionalIterator __i = __first; __i != __middle; + __d.template __incr<value_type>(), (void)++__i, (void)++__p) + ::new ((void*)__p) value_type(_IterOps<_AlgPolicy>::__iter_move(__i)); + std::__half_inplace_merge<_AlgPolicy>(__buff, __p, __middle, __last, __first, __comp); + } else { + value_type* __p = __buff; + for (_BidirectionalIterator __i = __middle; __i != __last; + __d.template __incr<value_type>(), (void)++__i, (void)++__p) + ::new ((void*)__p) value_type(_IterOps<_AlgPolicy>::__iter_move(__i)); + typedef __unconstrained_reverse_iterator<_BidirectionalIterator> _RBi; + typedef __unconstrained_reverse_iterator<value_type*> _Rv; + typedef __invert<_Compare> _Inverted; + std::__half_inplace_merge<_AlgPolicy>( + _Rv(__p), _Rv(__buff), _RBi(__middle), _RBi(__first), _RBi(__last), _Inverted(__comp)); + } +} + +template <class _AlgPolicy, class _Compare, class _BidirectionalIterator> +void __inplace_merge( + _BidirectionalIterator __first, + _BidirectionalIterator __middle, + _BidirectionalIterator __last, + _Compare&& __comp, + typename iterator_traits<_BidirectionalIterator>::difference_type __len1, + typename iterator_traits<_BidirectionalIterator>::difference_type __len2, + typename iterator_traits<_BidirectionalIterator>::value_type* __buff, + ptrdiff_t __buff_size) { + using _Ops = _IterOps<_AlgPolicy>; + + typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type; + while (true) { + // if __middle == __last, we're done + if (__len2 == 0) + return; + if (__len1 <= __buff_size || __len2 <= __buff_size) + return std::__buffered_inplace_merge<_AlgPolicy>(__first, __middle, __last, __comp, __len1, __len2, __buff); + // shrink [__first, __middle) as much as possible (with no moves), returning if it shrinks to 0 + for (; true; ++__first, (void)--__len1) { + if (__len1 == 0) + return; + if (__comp(*__middle, *__first)) + break; + } + // __first < __middle < __last + // *__first > *__middle + // partition [__first, __m1) [__m1, __middle) [__middle, __m2) [__m2, __last) such that + // all elements in: + // [__first, __m1) <= [__middle, __m2) + // [__middle, __m2) < [__m1, __middle) + // [__m1, __middle) <= [__m2, __last) + // and __m1 or __m2 is in the middle of its range + _BidirectionalIterator __m1; // "median" of [__first, __middle) + _BidirectionalIterator __m2; // "median" of [__middle, __last) + difference_type __len11; // distance(__first, __m1) + difference_type __len21; // distance(__middle, __m2) + // binary search smaller range + if (__len1 < __len2) { // __len >= 1, __len2 >= 2 + __len21 = __len2 / 2; + __m2 = __middle; + _Ops::advance(__m2, __len21); + __m1 = std::__upper_bound<_AlgPolicy>(__first, __middle, *__m2, __comp, std::__identity()); + __len11 = _Ops::distance(__first, __m1); + } else { + if (__len1 == 1) { // __len1 >= __len2 && __len2 > 0, therefore __len2 == 1 + // It is known *__first > *__middle + _Ops::iter_swap(__first, __middle); + return; + } + // __len1 >= 2, __len2 >= 1 + __len11 = __len1 / 2; + __m1 = __first; + _Ops::advance(__m1, __len11); + __m2 = std::lower_bound(__middle, __last, *__m1, __comp); + __len21 = _Ops::distance(__middle, __m2); + } + difference_type __len12 = __len1 - __len11; // distance(__m1, __middle) + difference_type __len22 = __len2 - __len21; // distance(__m2, __last) + // [__first, __m1) [__m1, __middle) [__middle, __m2) [__m2, __last) + // swap middle two partitions + __middle = std::__rotate<_AlgPolicy>(__m1, __middle, __m2).first; + // __len12 and __len21 now have swapped meanings + // merge smaller range with recursive call and larger with tail recursion elimination + if (__len11 + __len21 < __len12 + __len22) { + std::__inplace_merge<_AlgPolicy>(__first, __m1, __middle, __comp, __len11, __len21, __buff, __buff_size); + __first = __middle; + __middle = __m2; + __len1 = __len12; + __len2 = __len22; + } else { + std::__inplace_merge<_AlgPolicy>(__middle, __m2, __last, __comp, __len12, __len22, __buff, __buff_size); + __last = __middle; + __middle = __m1; + __len1 = __len11; + __len2 = __len21; + } + } +} + +template <class _AlgPolicy, class _BidirectionalIterator, class _Compare> +_LIBCPP_HIDE_FROM_ABI void __inplace_merge( + _BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last, _Compare&& __comp) { + typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type; + typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type; + difference_type __len1 = _IterOps<_AlgPolicy>::distance(__first, __middle); + difference_type __len2 = _IterOps<_AlgPolicy>::distance(__middle, __last); + difference_type __buf_size = std::min(__len1, __len2); + // TODO: Remove the use of std::get_temporary_buffer + _LIBCPP_SUPPRESS_DEPRECATED_PUSH + pair<value_type*, ptrdiff_t> __buf = std::get_temporary_buffer<value_type>(__buf_size); + _LIBCPP_SUPPRESS_DEPRECATED_POP + unique_ptr<value_type, __return_temporary_buffer> __h(__buf.first); + return std::__inplace_merge<_AlgPolicy>( + std::move(__first), std::move(__middle), std::move(__last), __comp, __len1, __len2, __buf.first, __buf.second); +} + +template <class _BidirectionalIterator, class _Compare> +inline _LIBCPP_HIDE_FROM_ABI void inplace_merge( + _BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last, _Compare __comp) { + std::__inplace_merge<_ClassicAlgPolicy>( + std::move(__first), std::move(__middle), std::move(__last), static_cast<__comp_ref_type<_Compare> >(__comp)); +} + +template <class _BidirectionalIterator> +inline _LIBCPP_HIDE_FROM_ABI void +inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _BidirectionalIterator __last) { + std::inplace_merge(std::move(__first), std::move(__middle), std::move(__last), __less<>()); +} + +_LIBCPP_END_NAMESPACE_STD + +_LIBCPP_POP_MACROS + +#endif // _LIBCPP___ALGORITHM_INPLACE_MERGE_H |