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_PARTIAL_SORT_H
10 #define _LIBCPP___ALGORITHM_PARTIAL_SORT_H
11
12 #include <__algorithm/comp.h>
13 #include <__algorithm/comp_ref_type.h>
14 #include <__algorithm/iterator_operations.h>
15 #include <__algorithm/make_heap.h>
16 #include <__algorithm/sift_down.h>
17 #include <__algorithm/sort_heap.h>
18 #include <__config>
19 #include <__debug>
20 #include <__debug_utils/randomize_range.h>
21 #include <__iterator/iterator_traits.h>
22 #include <__type_traits/is_copy_assignable.h>
23 #include <__type_traits/is_copy_constructible.h>
24 #include <__utility/move.h>
25
26 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
27 # pragma GCC system_header
28 #endif
29
30 _LIBCPP_BEGIN_NAMESPACE_STD
31
32 template <class _AlgPolicy, class _Compare, class _RandomAccessIterator, class _Sentinel>
33 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
__partial_sort_impl(_RandomAccessIterator __first,_RandomAccessIterator __middle,_Sentinel __last,_Compare && __comp)34 _RandomAccessIterator __partial_sort_impl(
35 _RandomAccessIterator __first, _RandomAccessIterator __middle, _Sentinel __last, _Compare&& __comp) {
36 if (__first == __middle) {
37 return _IterOps<_AlgPolicy>::next(__middle, __last);
38 }
39
40 std::__make_heap<_AlgPolicy>(__first, __middle, __comp);
41
42 typename iterator_traits<_RandomAccessIterator>::difference_type __len = __middle - __first;
43 _RandomAccessIterator __i = __middle;
44 for (; __i != __last; ++__i)
45 {
46 if (__comp(*__i, *__first))
47 {
48 _IterOps<_AlgPolicy>::iter_swap(__i, __first);
49 std::__sift_down<_AlgPolicy>(__first, __comp, __len, __first);
50 }
51 }
52 std::__sort_heap<_AlgPolicy>(std::move(__first), std::move(__middle), __comp);
53
54 return __i;
55 }
56
57 template <class _AlgPolicy, class _Compare, class _RandomAccessIterator, class _Sentinel>
58 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
__partial_sort(_RandomAccessIterator __first,_RandomAccessIterator __middle,_Sentinel __last,_Compare & __comp)59 _RandomAccessIterator __partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _Sentinel __last,
60 _Compare& __comp) {
61 if (__first == __middle)
62 return _IterOps<_AlgPolicy>::next(__middle, __last);
63
64 std::__debug_randomize_range<_AlgPolicy>(__first, __last);
65
66 auto __last_iter =
67 std::__partial_sort_impl<_AlgPolicy>(__first, __middle, __last, static_cast<__comp_ref_type<_Compare> >(__comp));
68
69 std::__debug_randomize_range<_AlgPolicy>(__middle, __last);
70
71 return __last_iter;
72 }
73
74 template <class _RandomAccessIterator, class _Compare>
75 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
76 void
partial_sort(_RandomAccessIterator __first,_RandomAccessIterator __middle,_RandomAccessIterator __last,_Compare __comp)77 partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last,
78 _Compare __comp)
79 {
80 static_assert(std::is_copy_constructible<_RandomAccessIterator>::value, "Iterators must be copy constructible.");
81 static_assert(std::is_copy_assignable<_RandomAccessIterator>::value, "Iterators must be copy assignable.");
82
83 (void)std::__partial_sort<_ClassicAlgPolicy>(std::move(__first), std::move(__middle), std::move(__last), __comp);
84 }
85
86 template <class _RandomAccessIterator>
87 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
88 void
partial_sort(_RandomAccessIterator __first,_RandomAccessIterator __middle,_RandomAccessIterator __last)89 partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last)
90 {
91 _VSTD::partial_sort(__first, __middle, __last,
92 __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
93 }
94
95 _LIBCPP_END_NAMESPACE_STD
96
97 #endif // _LIBCPP___ALGORITHM_PARTIAL_SORT_H
98