Source/WebCore/dom/ChildListMutationScope.cpp

/*
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#include "config.h"
#include "ChildListMutationScope.h"

#include "MutationObserverInterestGroup.h"
#include "MutationRecord.h"
#include "StaticNodeList.h"
#include <wtf/NeverDestroyed.h>
#include <wtf/StdLibExtras.h>

namespace WebCore {

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

ChildListMutationAccumulator::ChildListMutationAccumulator(ContainerNode& target, std::unique_ptr<MutationObserverInterestGroup> observers)
    : m_target(target)
    , m_lastAdded(nullptr)
    , m_observers(WTFMove(observers))
{
}

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

Ref<ChildListMutationAccumulator> ChildListMutationAccumulator::getOrCreate(ContainerNode& target)
{
    AccumulatorMap::AddResult result = accumulatorMap().add(&target, nullptr);
    RefPtr<ChildListMutationAccumulator> accumulator;
    if (!result.isNewEntry)
        accumulator = result.iterator->value;
    else {
        accumulator = adoptRef(new ChildListMutationAccumulator(target, MutationObserverInterestGroup::createForChildListMutation(target)));
        result.iterator->value = accumulator.get();
    }
    ASSERT(accumulator);
    return accumulator.releaseNonNull();
}

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

void ChildListMutationAccumulator::childAdded(Node& childRef)
{
    ASSERT(hasObservers());

    Ref<Node> child(childRef);

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

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

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

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

void ChildListMutationAccumulator::willRemoveChild(Node& childRef)
{
    ASSERT(hasObservers());

    Ref<Node> child(childRef);

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

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

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

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

    auto record = MutationRecord::createChildList(m_target, StaticNodeList::create(WTFMove(m_addedNodes)), StaticNodeList::create(WTFMove(m_removedNodes)), WTFMove(m_previousSibling), WTFMove(m_nextSibling));
    m_observers->enqueueMutationRecord(WTFMove(record));
    m_lastAdded = nullptr;
    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