Source/WebCore/dom/ChildListMutationScope.h

/*
 * Copyright (C) 2011 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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#pragma once

#include "ContainerNode.h"
#include "Document.h"
#include "MutationObserver.h"
#include <memory>
#include <wtf/Noncopyable.h>
#include <wtf/RefCounted.h>

namespace WebCore {

class MutationObserverInterestGroup;

// ChildListMutationAccumulator is not meant to be used directly; ChildListMutationScope is the public interface.
class ChildListMutationAccumulator : public RefCounted<ChildListMutationAccumulator> {
public:
    static Ref<ChildListMutationAccumulator> getOrCreate(ContainerNode&);
    ~ChildListMutationAccumulator();

    void childAdded(Node&);
    void willRemoveChild(Node&);

    bool hasObservers() const { return !!m_observers; }

private:
    ChildListMutationAccumulator(ContainerNode&, std::unique_ptr<MutationObserverInterestGroup>);

    void enqueueMutationRecord();
    bool isEmpty();
    bool isAddedNodeInOrder(Node&);
    bool isRemovedNodeInOrder(Node&);

    Ref<ContainerNode> m_target;

    Vector<Ref<Node>> m_removedNodes;
    Vector<Ref<Node>> m_addedNodes;
    RefPtr<Node> m_previousSibling;
    RefPtr<Node> m_nextSibling;
    Node* m_lastAdded;

    std::unique_ptr<MutationObserverInterestGroup> m_observers;
};

class ChildListMutationScope {
    WTF_MAKE_NONCOPYABLE(ChildListMutationScope);
public:
    explicit ChildListMutationScope(ContainerNode& target)
    {
        if (target.document().hasMutationObserversOfType(MutationObserver::ChildList))
            m_accumulator = ChildListMutationAccumulator::getOrCreate(target);
    }

    bool canObserve() const { return m_accumulator; }

    void childAdded(Node& child)
    {
        if (m_accumulator && m_accumulator->hasObservers())
            m_accumulator->childAdded(child);
    }

    void willRemoveChild(Node& child)
    {
        if (m_accumulator && m_accumulator->hasObservers())
            m_accumulator->willRemoveChild(child);
    }

private:
    RefPtr<ChildListMutationAccumulator> m_accumulator;
};

} // namespace WebCore