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 <__config> 13 #include <__iterator/iterator_traits.h> 14 #include <__utility/swap.h> 15 16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 17 #pragma GCC system_header 18 #endif 19 20 _LIBCPP_BEGIN_NAMESPACE_STD 21 22 template <class _Predicate, class _ForwardIterator> 23 _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator 24 __partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred, forward_iterator_tag) 25 { 26 while (true) 27 { 28 if (__first == __last) 29 return __first; 30 if (!__pred(*__first)) 31 break; 32 ++__first; 33 } 34 for (_ForwardIterator __p = __first; ++__p != __last;) 35 { 36 if (__pred(*__p)) 37 { 38 swap(*__first, *__p); 39 ++__first; 40 } 41 } 42 return __first; 43 } 44 45 template <class _Predicate, class _BidirectionalIterator> 46 _LIBCPP_CONSTEXPR_AFTER_CXX17 _BidirectionalIterator 47 __partition(_BidirectionalIterator __first, _BidirectionalIterator __last, _Predicate __pred, 48 bidirectional_iterator_tag) 49 { 50 while (true) 51 { 52 while (true) 53 { 54 if (__first == __last) 55 return __first; 56 if (!__pred(*__first)) 57 break; 58 ++__first; 59 } 60 do 61 { 62 if (__first == --__last) 63 return __first; 64 } while (!__pred(*__last)); 65 swap(*__first, *__last); 66 ++__first; 67 } 68 } 69 70 template <class _ForwardIterator, class _Predicate> 71 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 72 _ForwardIterator 73 partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred) 74 { 75 return _VSTD::__partition<_Predicate&>( 76 __first, __last, __pred, typename iterator_traits<_ForwardIterator>::iterator_category()); 77 } 78 79 _LIBCPP_END_NAMESPACE_STD 80 81 #endif // _LIBCPP___ALGORITHM_PARTITION_H 82