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 <__type_traits/remove_cvref.h> 16 #include <__utility/move.h> 17 #include <__utility/pair.h> 18 19 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 20 # pragma GCC system_header 21 #endif 22 23 _LIBCPP_PUSH_MACROS 24 #include <__undef_macros> 25 26 _LIBCPP_BEGIN_NAMESPACE_STD 27 28 template <class _Predicate, class _AlgPolicy, class _ForwardIterator, class _Sentinel> 29 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_ForwardIterator, _ForwardIterator> 30 __partition_impl(_ForwardIterator __first, _Sentinel __last, _Predicate __pred, forward_iterator_tag) { 31 while (true) { 32 if (__first == __last) 33 return std::make_pair(__first, __first); 34 if (!__pred(*__first)) 35 break; 36 ++__first; 37 } 38 39 _ForwardIterator __p = __first; 40 while (++__p != __last) { 41 if (__pred(*__p)) { 42 _IterOps<_AlgPolicy>::iter_swap(__first, __p); 43 ++__first; 44 } 45 } 46 return std::make_pair(std::move(__first), std::move(__p)); 47 } 48 49 template <class _Predicate, class _AlgPolicy, class _BidirectionalIterator, class _Sentinel> 50 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_BidirectionalIterator, _BidirectionalIterator> 51 __partition_impl(_BidirectionalIterator __first, _Sentinel __sentinel, _Predicate __pred, bidirectional_iterator_tag) { 52 _BidirectionalIterator __original_last = _IterOps<_AlgPolicy>::next(__first, __sentinel); 53 _BidirectionalIterator __last = __original_last; 54 55 while (true) { 56 while (true) { 57 if (__first == __last) 58 return std::make_pair(std::move(__first), std::move(__original_last)); 59 if (!__pred(*__first)) 60 break; 61 ++__first; 62 } 63 do { 64 if (__first == --__last) 65 return std::make_pair(std::move(__first), std::move(__original_last)); 66 } while (!__pred(*__last)); 67 _IterOps<_AlgPolicy>::iter_swap(__first, __last); 68 ++__first; 69 } 70 } 71 72 template <class _AlgPolicy, class _ForwardIterator, class _Sentinel, class _Predicate, class _IterCategory> 73 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_ForwardIterator, _ForwardIterator> 74 __partition(_ForwardIterator __first, _Sentinel __last, _Predicate&& __pred, _IterCategory __iter_category) { 75 return std::__partition_impl<__remove_cvref_t<_Predicate>&, _AlgPolicy>( 76 std::move(__first), std::move(__last), __pred, __iter_category); 77 } 78 79 template <class _ForwardIterator, class _Predicate> 80 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _ForwardIterator 81 partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred) { 82 using _IterCategory = typename iterator_traits<_ForwardIterator>::iterator_category; 83 auto __result = std::__partition<_ClassicAlgPolicy>(std::move(__first), std::move(__last), __pred, _IterCategory()); 84 return __result.first; 85 } 86 87 _LIBCPP_END_NAMESPACE_STD 88 89 _LIBCPP_POP_MACROS 90 91 #endif // _LIBCPP___ALGORITHM_PARTITION_H 92