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