Source/WebCore/dom/MutationObserverRegistration.cpp

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#include "config.h"

#include "MutationObserverRegistration.h"

#include "Document.h"
#include "JSNodeCustom.h"
#include "QualifiedName.h"

namespace WebCore {

MutationObserverRegistration::MutationObserverRegistration(MutationObserver& observer, Node& node, MutationObserverOptions options, const MemoryCompactLookupOnlyRobinHoodHashSet<AtomString>& attributeFilter)
    : m_observer(observer)
    , m_node(node)
    , m_options(options)
    , m_attributeFilter(attributeFilter)
{
    m_observer->observationStarted(*this);
}

MutationObserverRegistration::~MutationObserverRegistration()
{
    takeTransientRegistrations();
    m_observer->observationEnded(*this);
}

void MutationObserverRegistration::resetObservation(MutationObserverOptions options, const MemoryCompactLookupOnlyRobinHoodHashSet<AtomString>& attributeFilter)
{
    takeTransientRegistrations();
    m_options = options;
    m_attributeFilter = attributeFilter;
}

void MutationObserverRegistration::observedSubtreeNodeWillDetach(Node& node)
{
    if (!isSubtree())
        return;

    node.registerTransientMutationObserver(*this);
    m_observer->setHasTransientRegistration(node.document());

    if (m_transientRegistrationNodes.isEmpty()) {
        ASSERT(!m_nodeKeptAlive);
        m_nodeKeptAlive = &m_node; // Balanced in takeTransientRegistrations.
    }
    m_transientRegistrationNodes.add(node);
}

HashSet<GCReachableRef<Node>> MutationObserverRegistration::takeTransientRegistrations()
{
    if (m_transientRegistrationNodes.isEmpty()) {
        ASSERT(!m_nodeKeptAlive);
        return { };
    }

    for (auto& node : m_transientRegistrationNodes)
        node->unregisterTransientMutationObserver(*this);

    auto returnValue = std::exchange(m_transientRegistrationNodes, { });

    ASSERT(m_nodeKeptAlive);
    m_nodeKeptAlive = nullptr; // Balanced in observeSubtreeNodeWillDetach.

    return returnValue;
}

bool MutationObserverRegistration::shouldReceiveMutationFrom(Node& node, MutationObserverOptionType type, const QualifiedName* attributeName) const
{
    ASSERT((type == MutationObserverOptionType::Attributes && attributeName) || !attributeName);
    if (!m_options.contains(type))
        return false;

    if (&m_node != &node && !isSubtree())
        return false;

    if (type != MutationObserverOptionType::Attributes || !m_options.contains(MutationObserverOptionType::AttributeFilter))
        return true;

    if (!attributeName->namespaceURI().isNull())
        return false;

    return m_attributeFilter.contains(attributeName->localName());
}

bool MutationObserverRegistration::isReachableFromOpaqueRoots(JSC::AbstractSlotVisitor& visitor) const
{
    if (containsWebCoreOpaqueRoot(visitor, m_node))
        return true;

    for (auto& node : m_transientRegistrationNodes) {
        if (containsWebCoreOpaqueRoot(visitor, node.get()))
            return true;
    }

    return false;
}

} // namespace WebCore