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 <__config>
13 #include <__algorithm/comp.h>
14 #include <__algorithm/comp_ref_type.h>
15 #include <__algorithm/make_heap.h>
16 #include <__algorithm/sift_down.h>
17 #include <__algorithm/sort_heap.h>
18 #include <__iterator/iterator_traits.h>
19 #include <__utility/swap.h>
20 
21 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
22 #pragma GCC system_header
23 #endif
24 
25 _LIBCPP_BEGIN_NAMESPACE_STD
26 
27 template <class _Compare, class _RandomAccessIterator>
28 _LIBCPP_CONSTEXPR_AFTER_CXX17 void
29 __partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last,
30              _Compare __comp)
31 {
32     _VSTD::__make_heap<_Compare>(__first, __middle, __comp);
33     typename iterator_traits<_RandomAccessIterator>::difference_type __len = __middle - __first;
34     for (_RandomAccessIterator __i = __middle; __i != __last; ++__i)
35     {
36         if (__comp(*__i, *__first))
37         {
38             swap(*__i, *__first);
39             _VSTD::__sift_down<_Compare>(__first, __middle, __comp, __len, __first);
40         }
41     }
42     _VSTD::__sort_heap<_Compare>(__first, __middle, __comp);
43 }
44 
45 template <class _RandomAccessIterator, class _Compare>
46 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
47 void
48 partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last,
49              _Compare __comp)
50 {
51     typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
52     _VSTD::__partial_sort<_Comp_ref>(__first, __middle, __last, __comp);
53 }
54 
55 template <class _RandomAccessIterator>
56 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
57 void
58 partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last)
59 {
60     _VSTD::partial_sort(__first, __middle, __last,
61                        __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
62 }
63 
64 _LIBCPP_END_NAMESPACE_STD
65 
66 #endif // _LIBCPP___ALGORITHM_PARTIAL_SORT_H
67