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_POP_HEAP_H
10 #define _LIBCPP___ALGORITHM_POP_HEAP_H
11 
12 #include <__algorithm/comp.h>
13 #include <__algorithm/comp_ref_type.h>
14 #include <__algorithm/iterator_operations.h>
15 #include <__algorithm/push_heap.h>
16 #include <__algorithm/sift_down.h>
17 #include <__assert>
18 #include <__config>
19 #include <__iterator/iterator_traits.h>
20 #include <__type_traits/is_copy_assignable.h>
21 #include <__type_traits/is_copy_constructible.h>
22 #include <__utility/move.h>
23 
24 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
25 #  pragma GCC system_header
26 #endif
27 
28 _LIBCPP_PUSH_MACROS
29 #include <__undef_macros>
30 
31 _LIBCPP_BEGIN_NAMESPACE_STD
32 
33 template <class _AlgPolicy, class _Compare, class _RandomAccessIterator>
34 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void
35 __pop_heap(_RandomAccessIterator __first,
36            _RandomAccessIterator __last,
37            _Compare& __comp,
38            typename iterator_traits<_RandomAccessIterator>::difference_type __len) {
39   _LIBCPP_ASSERT_UNCATEGORIZED(__len > 0, "The heap given to pop_heap must be non-empty");
40 
41   __comp_ref_type<_Compare> __comp_ref = __comp;
42 
43   using value_type = typename iterator_traits<_RandomAccessIterator>::value_type;
44   if (__len > 1) {
45     value_type __top             = _IterOps<_AlgPolicy>::__iter_move(__first); // create a hole at __first
46     _RandomAccessIterator __hole = std::__floyd_sift_down<_AlgPolicy>(__first, __comp_ref, __len);
47     --__last;
48 
49     if (__hole == __last) {
50       *__hole = std::move(__top);
51     } else {
52       *__hole = _IterOps<_AlgPolicy>::__iter_move(__last);
53       ++__hole;
54       *__last = std::move(__top);
55       std::__sift_up<_AlgPolicy>(__first, __hole, __comp_ref, __hole - __first);
56     }
57   }
58 }
59 
60 template <class _RandomAccessIterator, class _Compare>
61 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void
62 pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) {
63   static_assert(std::is_copy_constructible<_RandomAccessIterator>::value, "Iterators must be copy constructible.");
64   static_assert(std::is_copy_assignable<_RandomAccessIterator>::value, "Iterators must be copy assignable.");
65 
66   typename iterator_traits<_RandomAccessIterator>::difference_type __len = __last - __first;
67   std::__pop_heap<_ClassicAlgPolicy>(std::move(__first), std::move(__last), __comp, __len);
68 }
69 
70 template <class _RandomAccessIterator>
71 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void
72 pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last) {
73   std::pop_heap(std::move(__first), std::move(__last), __less<>());
74 }
75 
76 _LIBCPP_END_NAMESPACE_STD
77 
78 _LIBCPP_POP_MACROS
79 
80 #endif // _LIBCPP___ALGORITHM_POP_HEAP_H
81