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 #include <type_traits>
18
19 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
20 # pragma GCC system_header
21 #endif
22
23 _LIBCPP_BEGIN_NAMESPACE_STD
24
25 template <class _Predicate, class _AlgPolicy, class _ForwardIterator, class _Sentinel>
26 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_ForwardIterator, _ForwardIterator>
__partition_impl(_ForwardIterator __first,_Sentinel __last,_Predicate __pred,forward_iterator_tag)27 __partition_impl(_ForwardIterator __first, _Sentinel __last, _Predicate __pred, forward_iterator_tag)
28 {
29 while (true)
30 {
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 {
41 if (__pred(*__p))
42 {
43 _IterOps<_AlgPolicy>::iter_swap(__first, __p);
44 ++__first;
45 }
46 }
47 return std::make_pair(std::move(__first), std::move(__p));
48 }
49
50 template <class _Predicate, class _AlgPolicy, class _BidirectionalIterator, class _Sentinel>
51 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_BidirectionalIterator, _BidirectionalIterator>
__partition_impl(_BidirectionalIterator __first,_Sentinel __sentinel,_Predicate __pred,bidirectional_iterator_tag)52 __partition_impl(_BidirectionalIterator __first, _Sentinel __sentinel, _Predicate __pred,
53 bidirectional_iterator_tag)
54 {
55 _BidirectionalIterator __original_last = _IterOps<_AlgPolicy>::next(__first, __sentinel);
56 _BidirectionalIterator __last = __original_last;
57
58 while (true)
59 {
60 while (true)
61 {
62 if (__first == __last)
63 return std::make_pair(std::move(__first), std::move(__original_last));
64 if (!__pred(*__first))
65 break;
66 ++__first;
67 }
68 do
69 {
70 if (__first == --__last)
71 return std::make_pair(std::move(__first), std::move(__original_last));
72 } while (!__pred(*__last));
73 _IterOps<_AlgPolicy>::iter_swap(__first, __last);
74 ++__first;
75 }
76 }
77
78 template <class _AlgPolicy, class _ForwardIterator, class _Sentinel, class _Predicate, class _IterCategory>
79 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
__partition(_ForwardIterator __first,_Sentinel __last,_Predicate && __pred,_IterCategory __iter_category)80 pair<_ForwardIterator, _ForwardIterator> __partition(
81 _ForwardIterator __first, _Sentinel __last, _Predicate&& __pred, _IterCategory __iter_category) {
82 return std::__partition_impl<__remove_cvref_t<_Predicate>&, _AlgPolicy>(
83 std::move(__first), std::move(__last), __pred, __iter_category);
84 }
85
86 template <class _ForwardIterator, class _Predicate>
87 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
88 _ForwardIterator
partition(_ForwardIterator __first,_ForwardIterator __last,_Predicate __pred)89 partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred)
90 {
91 using _IterCategory = typename iterator_traits<_ForwardIterator>::iterator_category;
92 auto __result = std::__partition<_ClassicAlgPolicy>(std::move(__first), std::move(__last), __pred, _IterCategory());
93 return __result.first;
94 }
95
96 _LIBCPP_END_NAMESPACE_STD
97
98 #endif // _LIBCPP___ALGORITHM_PARTITION_H
99