1 //===----------------------------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef _LIBCPP___ALGORITHM_PARTITION_H 10 #define _LIBCPP___ALGORITHM_PARTITION_H 11 12 #include <__algorithm/iterator_operations.h> 13 #include <__config> 14 #include <__iterator/iterator_traits.h> 15 #include <__utility/move.h> 16 #include <__utility/pair.h> 17 18 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 19 # pragma GCC system_header 20 #endif 21 22 _LIBCPP_BEGIN_NAMESPACE_STD 23 24 template <class _Predicate, class _AlgPolicy, class _ForwardIterator, class _Sentinel> 25 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_ForwardIterator, _ForwardIterator> 26 __partition_impl(_ForwardIterator __first, _Sentinel __last, _Predicate __pred, forward_iterator_tag) { 27 while (true) { 28 if (__first == __last) 29 return std::make_pair(std::move(__first), std::move(__first)); 30 if (!__pred(*__first)) 31 break; 32 ++__first; 33 } 34 35 _ForwardIterator __p = __first; 36 while (++__p != __last) { 37 if (__pred(*__p)) { 38 _IterOps<_AlgPolicy>::iter_swap(__first, __p); 39 ++__first; 40 } 41 } 42 return std::make_pair(std::move(__first), std::move(__p)); 43 } 44 45 template <class _Predicate, class _AlgPolicy, class _BidirectionalIterator, class _Sentinel> 46 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_BidirectionalIterator, _BidirectionalIterator> 47 __partition_impl(_BidirectionalIterator __first, _Sentinel __sentinel, _Predicate __pred, bidirectional_iterator_tag) { 48 _BidirectionalIterator __original_last = _IterOps<_AlgPolicy>::next(__first, __sentinel); 49 _BidirectionalIterator __last = __original_last; 50 51 while (true) { 52 while (true) { 53 if (__first == __last) 54 return std::make_pair(std::move(__first), std::move(__original_last)); 55 if (!__pred(*__first)) 56 break; 57 ++__first; 58 } 59 do { 60 if (__first == --__last) 61 return std::make_pair(std::move(__first), std::move(__original_last)); 62 } while (!__pred(*__last)); 63 _IterOps<_AlgPolicy>::iter_swap(__first, __last); 64 ++__first; 65 } 66 } 67 68 template <class _AlgPolicy, class _ForwardIterator, class _Sentinel, class _Predicate, class _IterCategory> 69 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_ForwardIterator, _ForwardIterator> 70 __partition(_ForwardIterator __first, _Sentinel __last, _Predicate&& __pred, _IterCategory __iter_category) { 71 return std::__partition_impl<__remove_cvref_t<_Predicate>&, _AlgPolicy>( 72 std::move(__first), std::move(__last), __pred, __iter_category); 73 } 74 75 template <class _ForwardIterator, class _Predicate> 76 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _ForwardIterator 77 partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred) { 78 using _IterCategory = typename iterator_traits<_ForwardIterator>::iterator_category; 79 auto __result = std::__partition<_ClassicAlgPolicy>(std::move(__first), std::move(__last), __pred, _IterCategory()); 80 return __result.first; 81 } 82 83 _LIBCPP_END_NAMESPACE_STD 84 85 #endif // _LIBCPP___ALGORITHM_PARTITION_H 86