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 #include <utility> // pair 16 #include <type_traits> 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 _ForwardIterator> 28 _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator 29 __partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred, forward_iterator_tag) 30 { 31 while (true) 32 { 33 if (__first == __last) 34 return __first; 35 if (!__pred(*__first)) 36 break; 37 ++__first; 38 } 39 for (_ForwardIterator __p = __first; ++__p != __last;) 40 { 41 if (__pred(*__p)) 42 { 43 swap(*__first, *__p); 44 ++__first; 45 } 46 } 47 return __first; 48 } 49 50 template <class _Predicate, class _BidirectionalIterator> 51 _LIBCPP_CONSTEXPR_AFTER_CXX17 _BidirectionalIterator 52 __partition(_BidirectionalIterator __first, _BidirectionalIterator __last, _Predicate __pred, 53 bidirectional_iterator_tag) 54 { 55 while (true) 56 { 57 while (true) 58 { 59 if (__first == __last) 60 return __first; 61 if (!__pred(*__first)) 62 break; 63 ++__first; 64 } 65 do 66 { 67 if (__first == --__last) 68 return __first; 69 } while (!__pred(*__last)); 70 swap(*__first, *__last); 71 ++__first; 72 } 73 } 74 75 template <class _ForwardIterator, class _Predicate> 76 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 77 _ForwardIterator 78 partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred) 79 { 80 return _VSTD::__partition<typename add_lvalue_reference<_Predicate>::type> 81 (__first, __last, __pred, typename iterator_traits<_ForwardIterator>::iterator_category()); 82 } 83 84 _LIBCPP_END_NAMESPACE_STD 85 86 _LIBCPP_POP_MACROS 87 88 #endif // _LIBCPP___ALGORITHM_PARTITION_H 89