1/*
2 * Copyright (C) 2011 Google 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 are
6 * met:
7 *
8 *     * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 *     * Redistributions in binary form must reproduce the above
11 * copyright notice, this list of conditions and the following disclaimer
12 * in the documentation and/or other materials provided with the
13 * distribution.
14 *     * Neither the name of Google Inc. nor the names of its
15 * contributors may be used to endorse or promote products derived from
16 * this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31#ifndef ChildListMutationScope_h
32#define ChildListMutationScope_h
33
34#include "core/dom/Document.h"
35#include "core/dom/MutationObserver.h"
36#include "core/dom/Node.h"
37#include "platform/heap/Handle.h"
38#include "wtf/Noncopyable.h"
39#include "wtf/OwnPtr.h"
40#include "wtf/RefCounted.h"
41
42namespace blink {
43
44class MutationObserverInterestGroup;
45
46// ChildListMutationAccumulator is not meant to be used directly; ChildListMutationScope is the public interface.
47//
48// One ChildListMutationAccumulator for a given Node is shared between all the
49// active ChildListMutationScopes for that Node. Once the last ChildListMutationScope
50// is destructed the accumulator enqueues a mutation record for the recorded
51// mutations and the accumulator can be garbage collected.
52class ChildListMutationAccumulator FINAL : public RefCountedWillBeGarbageCollected<ChildListMutationAccumulator> {
53    DECLARE_EMPTY_DESTRUCTOR_WILL_BE_REMOVED(ChildListMutationAccumulator);
54public:
55    static PassRefPtrWillBeRawPtr<ChildListMutationAccumulator> getOrCreate(Node&);
56
57    void childAdded(PassRefPtrWillBeRawPtr<Node>);
58    void willRemoveChild(PassRefPtrWillBeRawPtr<Node>);
59
60    bool hasObservers() const { return m_observers; }
61
62    // Register and unregister mutation scopes that are using this mutation
63    // accumulator.
64    void enterMutationScope() { m_mutationScopes++; }
65    void leaveMutationScope();
66
67    void trace(Visitor*);
68
69private:
70    ChildListMutationAccumulator(PassRefPtrWillBeRawPtr<Node>, PassOwnPtrWillBeRawPtr<MutationObserverInterestGroup>);
71
72    void enqueueMutationRecord();
73    bool isEmpty();
74    bool isAddedNodeInOrder(Node*);
75    bool isRemovedNodeInOrder(Node*);
76
77    RefPtrWillBeMember<Node> m_target;
78
79    WillBeHeapVector<RefPtrWillBeMember<Node> > m_removedNodes;
80    WillBeHeapVector<RefPtrWillBeMember<Node> > m_addedNodes;
81    RefPtrWillBeMember<Node> m_previousSibling;
82    RefPtrWillBeMember<Node> m_nextSibling;
83    RawPtrWillBeMember<Node> m_lastAdded;
84
85    OwnPtrWillBeMember<MutationObserverInterestGroup> m_observers;
86
87    unsigned m_mutationScopes;
88};
89
90class ChildListMutationScope FINAL {
91    WTF_MAKE_NONCOPYABLE(ChildListMutationScope);
92    STACK_ALLOCATED();
93public:
94    explicit ChildListMutationScope(Node& target)
95    {
96        if (target.document().hasMutationObserversOfType(MutationObserver::ChildList)) {
97            m_accumulator = ChildListMutationAccumulator::getOrCreate(target);
98            // Register another user of the accumulator.
99            m_accumulator->enterMutationScope();
100        }
101    }
102
103    ~ChildListMutationScope()
104    {
105        if (m_accumulator) {
106            // Unregister a user of the accumulator. If this is the last user
107            // the accumulator will enqueue a mutation record for the mutations.
108            m_accumulator->leaveMutationScope();
109        }
110    }
111
112    void childAdded(Node& child)
113    {
114        if (m_accumulator && m_accumulator->hasObservers())
115            m_accumulator->childAdded(&child);
116    }
117
118    void willRemoveChild(Node& child)
119    {
120        if (m_accumulator && m_accumulator->hasObservers())
121            m_accumulator->willRemoveChild(&child);
122    }
123
124private:
125    RefPtrWillBeMember<ChildListMutationAccumulator> m_accumulator;
126};
127
128} // namespace blink
129
130#endif // ChildListMutationScope_h
131