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