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
__pop_heap(_RandomAccessIterator __first,_RandomAccessIterator __last,_Compare & __comp,typename iterator_traits<_RandomAccessIterator>::difference_type __len)35 __pop_heap(_RandomAccessIterator __first,
36 _RandomAccessIterator __last,
37 _Compare& __comp,
38 typename iterator_traits<_RandomAccessIterator>::difference_type __len) {
39 // Calling `pop_heap` on an empty range is undefined behavior, but in practice it will be a no-op.
40 _LIBCPP_ASSERT_PEDANTIC(__len > 0, "The heap given to pop_heap must be non-empty");
41
42 __comp_ref_type<_Compare> __comp_ref = __comp;
43
44 using value_type = typename iterator_traits<_RandomAccessIterator>::value_type;
45 if (__len > 1) {
46 value_type __top = _IterOps<_AlgPolicy>::__iter_move(__first); // create a hole at __first
47 _RandomAccessIterator __hole = std::__floyd_sift_down<_AlgPolicy>(__first, __comp_ref, __len);
48 --__last;
49
50 if (__hole == __last) {
51 *__hole = std::move(__top);
52 } else {
53 *__hole = _IterOps<_AlgPolicy>::__iter_move(__last);
54 ++__hole;
55 *__last = std::move(__top);
56 std::__sift_up<_AlgPolicy>(__first, __hole, __comp_ref, __hole - __first);
57 }
58 }
59 }
60
61 template <class _RandomAccessIterator, class _Compare>
62 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void
pop_heap(_RandomAccessIterator __first,_RandomAccessIterator __last,_Compare __comp)63 pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) {
64 static_assert(std::is_copy_constructible<_RandomAccessIterator>::value, "Iterators must be copy constructible.");
65 static_assert(std::is_copy_assignable<_RandomAccessIterator>::value, "Iterators must be copy assignable.");
66
67 typename iterator_traits<_RandomAccessIterator>::difference_type __len = __last - __first;
68 std::__pop_heap<_ClassicAlgPolicy>(std::move(__first), std::move(__last), __comp, __len);
69 }
70
71 template <class _RandomAccessIterator>
72 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void
pop_heap(_RandomAccessIterator __first,_RandomAccessIterator __last)73 pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last) {
74 std::pop_heap(std::move(__first), std::move(__last), __less<>());
75 }
76
77 _LIBCPP_END_NAMESPACE_STD
78
79 _LIBCPP_POP_MACROS
80
81 #endif // _LIBCPP___ALGORITHM_POP_HEAP_H
82