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_PUSH_MACROS 23 #include <__undef_macros> 24 25 _LIBCPP_BEGIN_NAMESPACE_STD 26 27 template <class _Predicate, class _AlgPolicy, class _ForwardIterator, class _Sentinel> 28 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_ForwardIterator, _ForwardIterator> 29 __partition_impl(_ForwardIterator __first, _Sentinel __last, _Predicate __pred, forward_iterator_tag) { 30 while (true) { 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 if (__pred(*__p)) { 41 _IterOps<_AlgPolicy>::iter_swap(__first, __p); 42 ++__first; 43 } 44 } 45 return std::make_pair(std::move(__first), std::move(__p)); 46 } 47 48 template <class _Predicate, class _AlgPolicy, class _BidirectionalIterator, class _Sentinel> 49 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_BidirectionalIterator, _BidirectionalIterator> 50 __partition_impl(_BidirectionalIterator __first, _Sentinel __sentinel, _Predicate __pred, bidirectional_iterator_tag) { 51 _BidirectionalIterator __original_last = _IterOps<_AlgPolicy>::next(__first, __sentinel); 52 _BidirectionalIterator __last = __original_last; 53 54 while (true) { 55 while (true) { 56 if (__first == __last) 57 return std::make_pair(std::move(__first), std::move(__original_last)); 58 if (!__pred(*__first)) 59 break; 60 ++__first; 61 } 62 do { 63 if (__first == --__last) 64 return std::make_pair(std::move(__first), std::move(__original_last)); 65 } while (!__pred(*__last)); 66 _IterOps<_AlgPolicy>::iter_swap(__first, __last); 67 ++__first; 68 } 69 } 70 71 template <class _AlgPolicy, class _ForwardIterator, class _Sentinel, class _Predicate, class _IterCategory> 72 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_ForwardIterator, _ForwardIterator> 73 __partition(_ForwardIterator __first, _Sentinel __last, _Predicate&& __pred, _IterCategory __iter_category) { 74 return std::__partition_impl<__remove_cvref_t<_Predicate>&, _AlgPolicy>( 75 std::move(__first), std::move(__last), __pred, __iter_category); 76 } 77 78 template <class _ForwardIterator, class _Predicate> 79 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _ForwardIterator 80 partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred) { 81 using _IterCategory = typename iterator_traits<_ForwardIterator>::iterator_category; 82 auto __result = std::__partition<_ClassicAlgPolicy>(std::move(__first), std::move(__last), __pred, _IterCategory()); 83 return __result.first; 84 } 85 86 _LIBCPP_END_NAMESPACE_STD 87 88 _LIBCPP_POP_MACROS 89 90 #endif // _LIBCPP___ALGORITHM_PARTITION_H 91