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