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 <__type_traits/remove_cvref.h>
16#include <__utility/move.h>
17#include <__utility/pair.h>
18
19#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
20# pragma GCC system_header
21#endif
22
23_LIBCPP_PUSH_MACROS
24#include <__undef_macros>
25
26_LIBCPP_BEGIN_NAMESPACE_STD
27
28template <class _Predicate, class _AlgPolicy, class _ForwardIterator, class _Sentinel>
29_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_ForwardIterator, _ForwardIterator>
30__partition_impl(_ForwardIterator __first, _Sentinel __last, _Predicate __pred, forward_iterator_tag) {
31 while (true) {
32 if (__first == __last)
33 return std::make_pair(__first, __first);
34 if (!__pred(*__first))
35 break;
36 ++__first;
37 }
38
39 _ForwardIterator __p = __first;
40 while (++__p != __last) {
41 if (__pred(*__p)) {
42 _IterOps<_AlgPolicy>::iter_swap(__first, __p);
43 ++__first;
44 }
45 }
46 return std::make_pair(std::move(__first), std::move(__p));
47}
48
49template <class _Predicate, class _AlgPolicy, class _BidirectionalIterator, class _Sentinel>
50_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_BidirectionalIterator, _BidirectionalIterator>
51__partition_impl(_BidirectionalIterator __first, _Sentinel __sentinel, _Predicate __pred, bidirectional_iterator_tag) {
52 _BidirectionalIterator __original_last = _IterOps<_AlgPolicy>::next(__first, __sentinel);
53 _BidirectionalIterator __last = __original_last;
54
55 while (true) {
56 while (true) {
57 if (__first == __last)
58 return std::make_pair(std::move(__first), std::move(__original_last));
59 if (!__pred(*__first))
60 break;
61 ++__first;
62 }
63 do {
64 if (__first == --__last)
65 return std::make_pair(std::move(__first), std::move(__original_last));
66 } while (!__pred(*__last));
67 _IterOps<_AlgPolicy>::iter_swap(__first, __last);
68 ++__first;
69 }
70}
71
72template <class _AlgPolicy, class _ForwardIterator, class _Sentinel, class _Predicate, class _IterCategory>
73inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_ForwardIterator, _ForwardIterator>
74__partition(_ForwardIterator __first, _Sentinel __last, _Predicate&& __pred, _IterCategory __iter_category) {
75 return std::__partition_impl<__remove_cvref_t<_Predicate>&, _AlgPolicy>(
76 std::move(__first), std::move(__last), __pred, __iter_category);
77}
78
79template <class _ForwardIterator, class _Predicate>
80inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _ForwardIterator
81partition(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred) {
82 using _IterCategory = typename iterator_traits<_ForwardIterator>::iterator_category;
83 auto __result = std::__partition<_ClassicAlgPolicy>(std::move(__first), std::move(__last), __pred, _IterCategory());
84 return __result.first;
85}
86
87_LIBCPP_END_NAMESPACE_STD
88
89_LIBCPP_POP_MACROS
90
91#endif // _LIBCPP___ALGORITHM_PARTITION_H
92