Source/WebCore/dom/ChildListMutationScope.cpp

/*
 * Copyright (C) 2011 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions are
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 * in the documentation and/or other materials provided with the
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 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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#include "config.h"

#include "ChildListMutationScope.h"

#include "DocumentFragment.h"
#include "Element.h"
#include "MutationObserverInterestGroup.h"
#include "MutationRecord.h"
#include "Node.h"
#include "StaticNodeList.h"
#include <wtf/HashMap.h>
#include <wtf/OwnPtr.h>
#include <wtf/StdLibExtras.h>

namespace WebCore {

typedef HashMap<Node*, ChildListMutationAccumulator*> AccumulatorMap;
static AccumulatorMap& accumulatorMap()
{
    DEFINE_STATIC_LOCAL(AccumulatorMap, map, ());
    return map;
}

ChildListMutationAccumulator::ChildListMutationAccumulator(PassRefPtr<Node> target, PassOwnPtr<MutationObserverInterestGroup> observers)
    : m_target(target)
    , m_lastAdded(0)
    , m_observers(observers)
{
}

ChildListMutationAccumulator::~ChildListMutationAccumulator()
{
    if (!isEmpty())
        enqueueMutationRecord();
    accumulatorMap().remove(m_target.get());
}

PassRefPtr<ChildListMutationAccumulator> ChildListMutationAccumulator::getOrCreate(Node* target)
{
    AccumulatorMap::AddResult result = accumulatorMap().add(target, 0);
    RefPtr<ChildListMutationAccumulator> accumulator;
    if (!result.isNewEntry)
        accumulator = result.iterator->value;
    else {
        accumulator = adoptRef(new ChildListMutationAccumulator(target, MutationObserverInterestGroup::createForChildListMutation(target)));
        result.iterator->value = accumulator.get();
    }
    return accumulator.release();
}

inline bool ChildListMutationAccumulator::isAddedNodeInOrder(Node* child)
{
    return isEmpty() || (m_lastAdded == child->previousSibling() && m_nextSibling == child->nextSibling());
}

void ChildListMutationAccumulator::childAdded(PassRefPtr<Node> prpChild)
{
    ASSERT(hasObservers());

    RefPtr<Node> child = prpChild;

    if (!isAddedNodeInOrder(child.get()))
        enqueueMutationRecord();

    if (isEmpty()) {
        m_previousSibling = child->previousSibling();
        m_nextSibling = child->nextSibling();
    }

    m_lastAdded = child.get();
    m_addedNodes.append(child.release());
}

inline bool ChildListMutationAccumulator::isRemovedNodeInOrder(Node* child)
{
    return isEmpty() || m_nextSibling == child;
}

void ChildListMutationAccumulator::willRemoveChild(PassRefPtr<Node> prpChild)
{
    ASSERT(hasObservers());

    RefPtr<Node> child = prpChild;

    if (!m_addedNodes.isEmpty() || !isRemovedNodeInOrder(child.get()))
        enqueueMutationRecord();

    if (isEmpty()) {
        m_previousSibling = child->previousSibling();
        m_nextSibling = child->nextSibling();
        m_lastAdded = child->previousSibling();
    } else
        m_nextSibling = child->nextSibling();

    m_removedNodes.append(child.release());
}

void ChildListMutationAccumulator::enqueueMutationRecord()
{
    ASSERT(hasObservers());
    ASSERT(!isEmpty());

    RefPtr<NodeList> addedNodes = StaticNodeList::adopt(m_addedNodes);
    RefPtr<NodeList> removedNodes = StaticNodeList::adopt(m_removedNodes);
    RefPtr<MutationRecord> record = MutationRecord::createChildList(m_target, addedNodes.release(), removedNodes.release(), m_previousSibling.release(), m_nextSibling.release());
    m_observers->enqueueMutationRecord(record.release());
    m_lastAdded = 0;
    ASSERT(isEmpty());
}

bool ChildListMutationAccumulator::isEmpty()
{
    bool result = m_removedNodes.isEmpty() && m_addedNodes.isEmpty();
#ifndef NDEBUG
    if (result) {
        ASSERT(!m_previousSibling);
        ASSERT(!m_nextSibling);
        ASSERT(!m_lastAdded);
    }
#endif
    return result;
}

} // namespace WebCore