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 <__utility/move.h>
21 
22 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
23 #  pragma GCC system_header
24 #endif
25 
26 _LIBCPP_BEGIN_NAMESPACE_STD
27 
28 template <class _AlgPolicy, class _Compare, class _RandomAccessIterator>
29 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11
30 void __pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare& __comp,
31     typename iterator_traits<_RandomAccessIterator>::difference_type __len) {
32   _LIBCPP_ASSERT(__len > 0, "The heap given to pop_heap must be non-empty");
33 
34   using _CompRef = typename __comp_ref_type<_Compare>::type;
35   _CompRef __comp_ref = __comp;
36 
37   using value_type = typename iterator_traits<_RandomAccessIterator>::value_type;
38   if (__len > 1) {
39     value_type __top = _IterOps<_AlgPolicy>::__iter_move(__first);  // create a hole at __first
40     _RandomAccessIterator __hole = std::__floyd_sift_down<_AlgPolicy, _CompRef>(__first, __comp_ref, __len);
41     --__last;
42 
43     if (__hole == __last) {
44       *__hole = std::move(__top);
45     } else {
46       *__hole = _IterOps<_AlgPolicy>::__iter_move(__last);
47       ++__hole;
48       *__last = std::move(__top);
49       std::__sift_up<_AlgPolicy, _CompRef>(__first, __hole, __comp_ref, __hole - __first);
50     }
51   }
52 }
53 
54 template <class _RandomAccessIterator, class _Compare>
55 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17
56 void pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) {
57   typename iterator_traits<_RandomAccessIterator>::difference_type __len = __last - __first;
58   std::__pop_heap<_ClassicAlgPolicy>(std::move(__first), std::move(__last), __comp, __len);
59 }
60 
61 template <class _RandomAccessIterator>
62 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17
63 void pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last) {
64   std::pop_heap(std::move(__first), std::move(__last),
65       __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
66 }
67 
68 _LIBCPP_END_NAMESPACE_STD
69 
70 #endif // _LIBCPP___ALGORITHM_POP_HEAP_H
71