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Diffstat (limited to 'contrib/llvm-project/libcxx/include/__algorithm/stable_partition.h')
| -rw-r--r-- | contrib/llvm-project/libcxx/include/__algorithm/stable_partition.h | 303 |
1 files changed, 303 insertions, 0 deletions
diff --git a/contrib/llvm-project/libcxx/include/__algorithm/stable_partition.h b/contrib/llvm-project/libcxx/include/__algorithm/stable_partition.h new file mode 100644 index 000000000000..969ac7a6173e --- /dev/null +++ b/contrib/llvm-project/libcxx/include/__algorithm/stable_partition.h @@ -0,0 +1,303 @@ +//===----------------------------------------------------------------------===// +// +// 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_STABLE_PARTITION_H +#define _LIBCPP___ALGORITHM_STABLE_PARTITION_H + +#include <__algorithm/rotate.h> +#include <__config> +#include <__iterator/advance.h> +#include <__iterator/distance.h> +#include <__iterator/iterator_traits.h> +#include <__utility/swap.h> +#include <memory> + +#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) +# pragma GCC system_header +#endif + +_LIBCPP_BEGIN_NAMESPACE_STD + +template <class _Predicate, class _ForwardIterator, class _Distance, class _Pair> +_ForwardIterator +__stable_partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred, + _Distance __len, _Pair __p, forward_iterator_tag __fit) +{ + // *__first is known to be false + // __len >= 1 + if (__len == 1) + return __first; + if (__len == 2) + { + _ForwardIterator __m = __first; + if (__pred(*++__m)) + { + swap(*__first, *__m); + return __m; + } + return __first; + } + if (__len <= __p.second) + { // The buffer is big enough to use + typedef typename iterator_traits<_ForwardIterator>::value_type value_type; + __destruct_n __d(0); + unique_ptr<value_type, __destruct_n&> __h(__p.first, __d); + // Move the falses into the temporary buffer, and the trues to the front of the line + // Update __first to always point to the end of the trues + value_type* __t = __p.first; + ::new ((void*)__t) value_type(_VSTD::move(*__first)); + __d.template __incr<value_type>(); + ++__t; + _ForwardIterator __i = __first; + while (++__i != __last) + { + if (__pred(*__i)) + { + *__first = _VSTD::move(*__i); + ++__first; + } + else + { + ::new ((void*)__t) value_type(_VSTD::move(*__i)); + __d.template __incr<value_type>(); + ++__t; + } + } + // All trues now at start of range, all falses in buffer + // Move falses back into range, but don't mess up __first which points to first false + __i = __first; + for (value_type* __t2 = __p.first; __t2 < __t; ++__t2, (void) ++__i) + *__i = _VSTD::move(*__t2); + // __h destructs moved-from values out of the temp buffer, but doesn't deallocate buffer + return __first; + } + // Else not enough buffer, do in place + // __len >= 3 + _ForwardIterator __m = __first; + _Distance __len2 = __len / 2; // __len2 >= 2 + _VSTD::advance(__m, __len2); + // recurse on [__first, __m), *__first know to be false + // F????????????????? + // f m l + _ForwardIterator __first_false = _VSTD::__stable_partition<_Predicate&>(__first, __m, __pred, __len2, __p, __fit); + // TTTFFFFF?????????? + // f ff m l + // recurse on [__m, __last], except increase __m until *(__m) is false, *__last know to be true + _ForwardIterator __m1 = __m; + _ForwardIterator __second_false = __last; + _Distance __len_half = __len - __len2; + while (__pred(*__m1)) + { + if (++__m1 == __last) + goto __second_half_done; + --__len_half; + } + // TTTFFFFFTTTF?????? + // f ff m m1 l + __second_false = _VSTD::__stable_partition<_Predicate&>(__m1, __last, __pred, __len_half, __p, __fit); +__second_half_done: + // TTTFFFFFTTTTTFFFFF + // f ff m sf l + return _VSTD::rotate(__first_false, __m, __second_false); + // TTTTTTTTFFFFFFFFFF + // | +} + +template <class _Predicate, class _ForwardIterator> +_ForwardIterator +__stable_partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred, + forward_iterator_tag) +{ + const unsigned __alloc_limit = 3; // might want to make this a function of trivial assignment + // Either prove all true and return __first or point to first false + while (true) + { + if (__first == __last) + return __first; + if (!__pred(*__first)) + break; + ++__first; + } + // We now have a reduced range [__first, __last) + // *__first is known to be false + typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type; + typedef typename iterator_traits<_ForwardIterator>::value_type value_type; + difference_type __len = _VSTD::distance(__first, __last); + pair<value_type*, ptrdiff_t> __p(0, 0); + unique_ptr<value_type, __return_temporary_buffer> __h; + if (__len >= __alloc_limit) + { +// TODO: Remove the use of std::get_temporary_buffer +_LIBCPP_SUPPRESS_DEPRECATED_PUSH + __p = _VSTD::get_temporary_buffer<value_type>(__len); +_LIBCPP_SUPPRESS_DEPRECATED_POP + __h.reset(__p.first); + } + return _VSTD::__stable_partition<_Predicate&>(__first, __last, __pred, __len, __p, forward_iterator_tag()); +} + +template <class _Predicate, class _BidirectionalIterator, class _Distance, class _Pair> +_BidirectionalIterator +__stable_partition(_BidirectionalIterator __first, _BidirectionalIterator __last, _Predicate __pred, + _Distance __len, _Pair __p, bidirectional_iterator_tag __bit) +{ + // *__first is known to be false + // *__last is known to be true + // __len >= 2 + if (__len == 2) + { + swap(*__first, *__last); + return __last; + } + if (__len == 3) + { + _BidirectionalIterator __m = __first; + if (__pred(*++__m)) + { + swap(*__first, *__m); + swap(*__m, *__last); + return __last; + } + swap(*__m, *__last); + swap(*__first, *__m); + return __m; + } + if (__len <= __p.second) + { // The buffer is big enough to use + typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type; + __destruct_n __d(0); + unique_ptr<value_type, __destruct_n&> __h(__p.first, __d); + // Move the falses into the temporary buffer, and the trues to the front of the line + // Update __first to always point to the end of the trues + value_type* __t = __p.first; + ::new ((void*)__t) value_type(_VSTD::move(*__first)); + __d.template __incr<value_type>(); + ++__t; + _BidirectionalIterator __i = __first; + while (++__i != __last) + { + if (__pred(*__i)) + { + *__first = _VSTD::move(*__i); + ++__first; + } + else + { + ::new ((void*)__t) value_type(_VSTD::move(*__i)); + __d.template __incr<value_type>(); + ++__t; + } + } + // move *__last, known to be true + *__first = _VSTD::move(*__i); + __i = ++__first; + // All trues now at start of range, all falses in buffer + // Move falses back into range, but don't mess up __first which points to first false + for (value_type* __t2 = __p.first; __t2 < __t; ++__t2, (void) ++__i) + *__i = _VSTD::move(*__t2); + // __h destructs moved-from values out of the temp buffer, but doesn't deallocate buffer + return __first; + } + // Else not enough buffer, do in place + // __len >= 4 + _BidirectionalIterator __m = __first; + _Distance __len2 = __len / 2; // __len2 >= 2 + _VSTD::advance(__m, __len2); + // recurse on [__first, __m-1], except reduce __m-1 until *(__m-1) is true, *__first know to be false + // F????????????????T + // f m l + _BidirectionalIterator __m1 = __m; + _BidirectionalIterator __first_false = __first; + _Distance __len_half = __len2; + while (!__pred(*--__m1)) + { + if (__m1 == __first) + goto __first_half_done; + --__len_half; + } + // F???TFFF?????????T + // f m1 m l + __first_false = _VSTD::__stable_partition<_Predicate&>(__first, __m1, __pred, __len_half, __p, __bit); +__first_half_done: + // TTTFFFFF?????????T + // f ff m l + // recurse on [__m, __last], except increase __m until *(__m) is false, *__last know to be true + __m1 = __m; + _BidirectionalIterator __second_false = __last; + ++__second_false; + __len_half = __len - __len2; + while (__pred(*__m1)) + { + if (++__m1 == __last) + goto __second_half_done; + --__len_half; + } + // TTTFFFFFTTTF?????T + // f ff m m1 l + __second_false = _VSTD::__stable_partition<_Predicate&>(__m1, __last, __pred, __len_half, __p, __bit); +__second_half_done: + // TTTFFFFFTTTTTFFFFF + // f ff m sf l + return _VSTD::rotate(__first_false, __m, __second_false); + // TTTTTTTTFFFFFFFFFF + // | +} + +template <class _Predicate, class _BidirectionalIterator> +_BidirectionalIterator +__stable_partition(_BidirectionalIterator __first, _BidirectionalIterator __last, _Predicate __pred, + bidirectional_iterator_tag) +{ + typedef typename iterator_traits<_BidirectionalIterator>::difference_type difference_type; + typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type; + const difference_type __alloc_limit = 4; // might want to make this a function of trivial assignment + // Either prove all true and return __first or point to first false + while (true) + { + if (__first == __last) + return __first; + if (!__pred(*__first)) + break; + ++__first; + } + // __first points to first false, everything prior to __first is already set. + // Either prove [__first, __last) is all false and return __first, or point __last to last true + do + { + if (__first == --__last) + return __first; + } while (!__pred(*__last)); + // We now have a reduced range [__first, __last] + // *__first is known to be false + // *__last is known to be true + // __len >= 2 + difference_type __len = _VSTD::distance(__first, __last) + 1; + pair<value_type*, ptrdiff_t> __p(0, 0); + unique_ptr<value_type, __return_temporary_buffer> __h; + if (__len >= __alloc_limit) + { +// TODO: Remove the use of std::get_temporary_buffer +_LIBCPP_SUPPRESS_DEPRECATED_PUSH + __p = _VSTD::get_temporary_buffer<value_type>(__len); +_LIBCPP_SUPPRESS_DEPRECATED_POP + __h.reset(__p.first); + } + return _VSTD::__stable_partition<_Predicate&>(__first, __last, __pred, __len, __p, bidirectional_iterator_tag()); +} + +template <class _ForwardIterator, class _Predicate> +inline _LIBCPP_INLINE_VISIBILITY +_ForwardIterator +stable_partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred) +{ + return _VSTD::__stable_partition<_Predicate&>(__first, __last, __pred, typename iterator_traits<_ForwardIterator>::iterator_category()); +} + +_LIBCPP_END_NAMESPACE_STD + +#endif // _LIBCPP___ALGORITHM_STABLE_PARTITION_H |