1/*
2 * Copyright (C) 2017, 2019 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
23 * THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#pragma once
27
28#include <wtf/Algorithms.h>
29#include <wtf/HashSet.h>
30#include <wtf/HashTraits.h>
31#include <wtf/WeakPtr.h>
32
33namespace WTF {
34
35template <typename T>
36class WeakHashSet {
37public:
38 typedef HashSet<Ref<WeakReference<T>>> WeakReferenceSet;
39
40 class WeakHashSetConstIterator : public std::iterator<std::forward_iterator_tag, T, std::ptrdiff_t, const T*, const T&> {
41 private:
42 WeakHashSetConstIterator(const WeakReferenceSet& set, typename WeakReferenceSet::const_iterator position)
43 : m_position(position), m_endPosition(set.end())
44 {
45 skipEmptyBuckets();
46 }
47
48 public:
49 T* get() const { return m_position->get().get(); }
50 T& operator*() const { return *get(); }
51 T* operator->() const { return get(); }
52
53 WeakHashSetConstIterator& operator++()
54 {
55 ASSERT(m_position != m_endPosition);
56 ++m_position;
57 skipEmptyBuckets();
58 return *this;
59 }
60
61 void skipEmptyBuckets()
62 {
63 while (m_position != m_endPosition && !m_position->get().get())
64 ++m_position;
65 }
66
67 bool operator==(const WeakHashSetConstIterator& other) const
68 {
69 return m_position == other.m_position;
70 }
71
72 bool operator!=(const WeakHashSetConstIterator& other) const
73 {
74 return m_position != other.m_position;
75 }
76
77 private:
78 template <typename> friend class WeakHashSet;
79
80 typename WeakReferenceSet::const_iterator m_position;
81 typename WeakReferenceSet::const_iterator m_endPosition;
82 };
83 typedef WeakHashSetConstIterator const_iterator;
84
85 WeakHashSet() { }
86
87 const_iterator begin() const { return WeakHashSetConstIterator(m_set, m_set.begin()); }
88 const_iterator end() const { return WeakHashSetConstIterator(m_set, m_set.end()); }
89
90 template <typename U>
91 void add(const U& value)
92 {
93 m_set.add(*makeWeakPtr<T>(const_cast<U&>(value)).m_ref);
94 }
95
96 template <typename U>
97 bool remove(const U& value)
98 {
99 auto* weakReference = weak_reference_downcast<T>(value.weakPtrFactory().m_ref.get());
100 if (!weakReference)
101 return false;
102 return m_set.remove(weakReference);
103 }
104
105 template <typename U>
106 bool contains(const U& value) const
107 {
108 auto* weakReference = weak_reference_downcast<T>(value.weakPtrFactory().m_ref.get());
109 if (!weakReference)
110 return false;
111 return m_set.contains(weakReference);
112 }
113
114 unsigned capacity() const { return m_set.capacity(); }
115
116 bool computesEmpty() const
117 {
118 if (m_set.isEmpty())
119 return true;
120 for (auto& value : m_set) {
121 if (value->get())
122 return false;
123 }
124 return true;
125 }
126
127 bool hasNullReferences() const
128 {
129 return WTF::anyOf(m_set, [] (auto& value) { return !value->get(); });
130 }
131
132 unsigned computeSize() const
133 {
134 const_cast<WeakReferenceSet&>(m_set).removeIf([] (auto& value) { return !value->get(); });
135 return m_set.size();
136 }
137
138#if ASSERT_DISABLED
139 void checkConsistency() const { }
140#else
141 void checkConsistency() const { m_set.checkConsistency(); }
142#endif
143
144private:
145 WeakReferenceSet m_set;
146};
147
148template<typename T> struct HashTraits<Ref<WeakReference<T>>> : RefHashTraits<WeakReference<T>> {
149 static const bool hasIsReleasedWeakValueFunction = true;
150 static bool isReleasedWeakValue(const Ref<WeakReference<T>>& value)
151 {
152 return !value.isHashTableDeletedValue() && !value.isHashTableEmptyValue() && !value.get().get();
153 }
154};
155
156} // namespace WTF
157
158using WTF::WeakHashSet;
159