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
27template <class _Predicate, class _AlgPolicy, class _ForwardIterator, class _Sentinel>
28_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_ForwardIterator, _ForwardIterator>
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
48template <class _Predicate, class _AlgPolicy, class _BidirectionalIterator, class _Sentinel>
49_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_BidirectionalIterator, _BidirectionalIterator>
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
71template <class _AlgPolicy, class _ForwardIterator, class _Sentinel, class _Predicate, class _IterCategory>
72inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_ForwardIterator, _ForwardIterator>
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
78template <class _ForwardIterator, class _Predicate>
79inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _ForwardIterator
80partition(_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