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 <type_traits> 15 16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 17 #pragma GCC system_header 18 #endif 19 20 _LIBCPP_PUSH_MACROS 21 #include <__undef_macros> 22 23 _LIBCPP_BEGIN_NAMESPACE_STD 24 25 template <class _Predicate, class _ForwardIterator> 26 _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator 27 __partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred, forward_iterator_tag) 28 { 29 while (true) 30 { 31 if (__first == __last) 32 return __first; 33 if (!__pred(*__first)) 34 break; 35 ++__first; 36 } 37 for (_ForwardIterator __p = __first; ++__p != __last;) 38 { 39 if (__pred(*__p)) 40 { 41 swap(*__first, *__p); 42 ++__first; 43 } 44 } 45 return __first; 46 } 47 48 template <class _Predicate, class _BidirectionalIterator> 49 _LIBCPP_CONSTEXPR_AFTER_CXX17 _BidirectionalIterator 50 __partition(_BidirectionalIterator __first, _BidirectionalIterator __last, _Predicate __pred, 51 bidirectional_iterator_tag) 52 { 53 while (true) 54 { 55 while (true) 56 { 57 if (__first == __last) 58 return __first; 59 if (!__pred(*__first)) 60 break; 61 ++__first; 62 } 63 do 64 { 65 if (__first == --__last) 66 return __first; 67 } while (!__pred(*__last)); 68 swap(*__first, *__last); 69 ++__first; 70 } 71 } 72 73 template <class _ForwardIterator, class _Predicate> 74 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 75 _ForwardIterator 76 partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred) 77 { 78 return _VSTD::__partition<typename add_lvalue_reference<_Predicate>::type> 79 (__first, __last, __pred, typename iterator_traits<_ForwardIterator>::iterator_category()); 80 } 81 82 _LIBCPP_END_NAMESPACE_STD 83 84 _LIBCPP_POP_MACROS 85 86 #endif // _LIBCPP___ALGORITHM_PARTITION_H 87