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_COPY_H
10 #define _LIBCPP___ALGORITHM_PARTIAL_SORT_COPY_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/make_projected.h>
17 #include <__algorithm/sift_down.h>
18 #include <__algorithm/sort_heap.h>
19 #include <__config>
20 #include <__functional/identity.h>
21 #include <__functional/invoke.h>
22 #include <__iterator/iterator_traits.h>
23 #include <__type_traits/is_callable.h>
24 #include <__utility/move.h>
25 #include <__utility/pair.h>
26 
27 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
28 #  pragma GCC system_header
29 #endif
30 
31 _LIBCPP_BEGIN_NAMESPACE_STD
32 
33 template <class _AlgPolicy, class _Compare,
34           class _InputIterator, class _Sentinel1, class _RandomAccessIterator, class _Sentinel2,
35           class _Proj1, class _Proj2>
36 _LIBCPP_CONSTEXPR_AFTER_CXX17 pair<_InputIterator, _RandomAccessIterator>
37 __partial_sort_copy(_InputIterator __first, _Sentinel1 __last,
38                     _RandomAccessIterator __result_first, _Sentinel2 __result_last,
39                     _Compare&& __comp, _Proj1&& __proj1, _Proj2&& __proj2)
40 {
41     _RandomAccessIterator __r = __result_first;
42     auto&& __projected_comp = std::__make_projected(__comp, __proj2);
43 
44     if (__r != __result_last)
45     {
46         for (; __first != __last && __r != __result_last; ++__first, (void) ++__r)
47             *__r = *__first;
48         std::__make_heap<_AlgPolicy>(__result_first, __r, __projected_comp);
49         typename iterator_traits<_RandomAccessIterator>::difference_type __len = __r - __result_first;
50         for (; __first != __last; ++__first)
51             if (std::__invoke(__comp, std::__invoke(__proj1, *__first), std::__invoke(__proj2, *__result_first))) {
52                 *__result_first = *__first;
53                 std::__sift_down<_AlgPolicy>(__result_first, __projected_comp, __len, __result_first);
54             }
55         std::__sort_heap<_AlgPolicy>(__result_first, __r, __projected_comp);
56     }
57 
58     return pair<_InputIterator, _RandomAccessIterator>(
59         _IterOps<_AlgPolicy>::next(std::move(__first), std::move(__last)), std::move(__r));
60 }
61 
62 template <class _InputIterator, class _RandomAccessIterator, class _Compare>
63 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
64 _RandomAccessIterator
65 partial_sort_copy(_InputIterator __first, _InputIterator __last,
66                   _RandomAccessIterator __result_first, _RandomAccessIterator __result_last, _Compare __comp)
67 {
68   static_assert(__is_callable<_Compare, decltype(*__first), decltype(*__result_first)>::value,
69                 "Comparator has to be callable");
70 
71   using _Comp_ref = typename __comp_ref_type<_Compare>::type;
72   auto __result = std::__partial_sort_copy<_ClassicAlgPolicy>(__first, __last, __result_first, __result_last,
73       static_cast<_Comp_ref>(__comp), __identity(), __identity());
74   return __result.second;
75 }
76 
77 template <class _InputIterator, class _RandomAccessIterator>
78 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
79 _RandomAccessIterator
80 partial_sort_copy(_InputIterator __first, _InputIterator __last,
81                   _RandomAccessIterator __result_first, _RandomAccessIterator __result_last)
82 {
83     return _VSTD::partial_sort_copy(__first, __last, __result_first, __result_last,
84                                    __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
85 }
86 
87 _LIBCPP_END_NAMESPACE_STD
88 
89 #endif // _LIBCPP___ALGORITHM_PARTIAL_SORT_COPY_H
90