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 #include <type_traits> 18 19 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 20 # pragma GCC system_header 21 #endif 22 23 _LIBCPP_BEGIN_NAMESPACE_STD 24 25 template <class _Predicate, class _AlgPolicy, class _ForwardIterator, class _Sentinel> 26 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_ForwardIterator, _ForwardIterator> 27 __partition_impl(_ForwardIterator __first, _Sentinel __last, _Predicate __pred, forward_iterator_tag) 28 { 29 while (true) 30 { 31 if (__first == __last) 32 return std::make_pair(std::move(__first), std::move(__first)); 33 if (!__pred(*__first)) 34 break; 35 ++__first; 36 } 37 38 _ForwardIterator __p = __first; 39 while (++__p != __last) 40 { 41 if (__pred(*__p)) 42 { 43 _IterOps<_AlgPolicy>::iter_swap(__first, __p); 44 ++__first; 45 } 46 } 47 return std::make_pair(std::move(__first), std::move(__p)); 48 } 49 50 template <class _Predicate, class _AlgPolicy, class _BidirectionalIterator, class _Sentinel> 51 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_BidirectionalIterator, _BidirectionalIterator> 52 __partition_impl(_BidirectionalIterator __first, _Sentinel __sentinel, _Predicate __pred, 53 bidirectional_iterator_tag) 54 { 55 _BidirectionalIterator __original_last = _IterOps<_AlgPolicy>::next(__first, __sentinel); 56 _BidirectionalIterator __last = __original_last; 57 58 while (true) 59 { 60 while (true) 61 { 62 if (__first == __last) 63 return std::make_pair(std::move(__first), std::move(__original_last)); 64 if (!__pred(*__first)) 65 break; 66 ++__first; 67 } 68 do 69 { 70 if (__first == --__last) 71 return std::make_pair(std::move(__first), std::move(__original_last)); 72 } while (!__pred(*__last)); 73 _IterOps<_AlgPolicy>::iter_swap(__first, __last); 74 ++__first; 75 } 76 } 77 78 template <class _AlgPolicy, class _ForwardIterator, class _Sentinel, class _Predicate, class _IterCategory> 79 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 80 pair<_ForwardIterator, _ForwardIterator> __partition( 81 _ForwardIterator __first, _Sentinel __last, _Predicate&& __pred, _IterCategory __iter_category) { 82 return std::__partition_impl<__remove_cvref_t<_Predicate>&, _AlgPolicy>( 83 std::move(__first), std::move(__last), __pred, __iter_category); 84 } 85 86 template <class _ForwardIterator, class _Predicate> 87 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20 88 _ForwardIterator 89 partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred) 90 { 91 using _IterCategory = typename iterator_traits<_ForwardIterator>::iterator_category; 92 auto __result = std::__partition<_ClassicAlgPolicy>(std::move(__first), std::move(__last), __pred, _IterCategory()); 93 return __result.first; 94 } 95 96 _LIBCPP_END_NAMESPACE_STD 97 98 #endif // _LIBCPP___ALGORITHM_PARTITION_H 99