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_ref_type.h>
14 #include <__algorithm/make_heap.h>
15 #include <__algorithm/sift_down.h>
16 #include <__algorithm/sort_heap.h>
17 #include <__iterator/iterator_traits.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 
28 template <class _Compare, class _RandomAccessIterator>
29 _LIBCPP_CONSTEXPR_AFTER_CXX17 void
30 __partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last,
31              _Compare __comp)
32 {
33     _VSTD::__make_heap<_Compare>(__first, __middle, __comp);
34     typename iterator_traits<_RandomAccessIterator>::difference_type __len = __middle - __first;
35     for (_RandomAccessIterator __i = __middle; __i != __last; ++__i)
36     {
37         if (__comp(*__i, *__first))
38         {
39             swap(*__i, *__first);
40             _VSTD::__sift_down<_Compare>(__first, __middle, __comp, __len, __first);
41         }
42     }
43     _VSTD::__sort_heap<_Compare>(__first, __middle, __comp);
44 }
45 
46 template <class _RandomAccessIterator, class _Compare>
47 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
48 void
49 partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last,
50              _Compare __comp)
51 {
52     typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
53     _VSTD::__partial_sort<_Comp_ref>(__first, __middle, __last, __comp);
54 }
55 
56 template <class _RandomAccessIterator>
57 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
58 void
59 partial_sort(_RandomAccessIterator __first, _RandomAccessIterator __middle, _RandomAccessIterator __last)
60 {
61     _VSTD::partial_sort(__first, __middle, __last,
62                        __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
63 }
64 
65 // partial_sort_copy
66 
67 template <class _Compare, class _InputIterator, class _RandomAccessIterator>
68 _LIBCPP_CONSTEXPR_AFTER_CXX17 _RandomAccessIterator
69 __partial_sort_copy(_InputIterator __first, _InputIterator __last,
70                     _RandomAccessIterator __result_first, _RandomAccessIterator __result_last, _Compare __comp)
71 {
72     _RandomAccessIterator __r = __result_first;
73     if (__r != __result_last)
74     {
75         for (; __first != __last && __r != __result_last; ++__first, (void) ++__r)
76             *__r = *__first;
77         _VSTD::__make_heap<_Compare>(__result_first, __r, __comp);
78         typename iterator_traits<_RandomAccessIterator>::difference_type __len = __r - __result_first;
79         for (; __first != __last; ++__first)
80             if (__comp(*__first, *__result_first))
81             {
82                 *__result_first = *__first;
83                 _VSTD::__sift_down<_Compare>(__result_first, __r, __comp, __len, __result_first);
84             }
85         _VSTD::__sort_heap<_Compare>(__result_first, __r, __comp);
86     }
87     return __r;
88 }
89 
90 template <class _InputIterator, class _RandomAccessIterator, class _Compare>
91 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
92 _RandomAccessIterator
93 partial_sort_copy(_InputIterator __first, _InputIterator __last,
94                   _RandomAccessIterator __result_first, _RandomAccessIterator __result_last, _Compare __comp)
95 {
96     typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
97     return _VSTD::__partial_sort_copy<_Comp_ref>(__first, __last, __result_first, __result_last, __comp);
98 }
99 
100 template <class _InputIterator, class _RandomAccessIterator>
101 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
102 _RandomAccessIterator
103 partial_sort_copy(_InputIterator __first, _InputIterator __last,
104                   _RandomAccessIterator __result_first, _RandomAccessIterator __result_last)
105 {
106     return _VSTD::partial_sort_copy(__first, __last, __result_first, __result_last,
107                                    __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
108 }
109 
110 _LIBCPP_END_NAMESPACE_STD
111 
112 _LIBCPP_POP_MACROS
113 
114 #endif // _LIBCPP___ALGORITHM_PARTIAL_SORT_H
115