MutationObserver.cpp [plain text]
#include "config.h"
#include "MutationObserver.h"
#include "Document.h"
#include "ExceptionCode.h"
#include "HTMLSlotElement.h"
#include "Microtasks.h"
#include "MutationCallback.h"
#include "MutationObserverRegistration.h"
#include "MutationRecord.h"
#include <algorithm>
#include <wtf/MainThread.h>
namespace WebCore {
static unsigned s_observerPriority = 0;
Ref<MutationObserver> MutationObserver::create(Ref<MutationCallback>&& callback)
{
ASSERT(isMainThread());
return adoptRef(*new MutationObserver(WTFMove(callback)));
}
MutationObserver::MutationObserver(Ref<MutationCallback>&& callback)
: m_callback(WTFMove(callback))
, m_priority(s_observerPriority++)
{
}
MutationObserver::~MutationObserver()
{
ASSERT(m_registrations.isEmpty());
}
bool MutationObserver::validateOptions(MutationObserverOptions options)
{
return (options & (Attributes | CharacterData | ChildList))
&& ((options & Attributes) || !(options & AttributeOldValue))
&& ((options & Attributes) || !(options & AttributeFilter))
&& ((options & CharacterData) || !(options & CharacterDataOldValue));
}
ExceptionOr<void> MutationObserver::observe(Node& node, const Init& init)
{
MutationObserverOptions options = 0;
if (init.childList)
options |= ChildList;
if (init.subtree)
options |= Subtree;
if (init.attributeOldValue.value_or(false))
options |= AttributeOldValue;
if (init.characterDataOldValue.value_or(false))
options |= CharacterDataOldValue;
HashSet<AtomicString> attributeFilter;
if (init.attributeFilter) {
for (auto& value : init.attributeFilter.value())
attributeFilter.add(value);
options |= AttributeFilter;
}
if (init.attributes ? init.attributes.value() : (options & (AttributeFilter | AttributeOldValue)))
options |= Attributes;
if (init.characterData ? init.characterData.value() : (options & CharacterDataOldValue))
options |= CharacterData;
if (!validateOptions(options))
return Exception { TypeError };
node.registerMutationObserver(*this, options, attributeFilter);
return { };
}
Vector<Ref<MutationRecord>> MutationObserver::takeRecords()
{
Vector<Ref<MutationRecord>> records;
records.swap(m_records);
return records;
}
void MutationObserver::disconnect()
{
m_records.clear();
HashSet<MutationObserverRegistration*> registrations(m_registrations);
for (auto* registration : registrations)
registration->node().unregisterMutationObserver(*registration);
}
void MutationObserver::observationStarted(MutationObserverRegistration& registration)
{
ASSERT(!m_registrations.contains(®istration));
m_registrations.add(®istration);
}
void MutationObserver::observationEnded(MutationObserverRegistration& registration)
{
ASSERT(m_registrations.contains(®istration));
m_registrations.remove(®istration);
}
typedef HashSet<RefPtr<MutationObserver>> MutationObserverSet;
static MutationObserverSet& activeMutationObservers()
{
static NeverDestroyed<MutationObserverSet> activeObservers;
return activeObservers;
}
static MutationObserverSet& suspendedMutationObservers()
{
static NeverDestroyed<MutationObserverSet> suspendedObservers;
return suspendedObservers;
}
static Vector<RefPtr<HTMLSlotElement>>& signalSlotList()
{
static NeverDestroyed<Vector<RefPtr<HTMLSlotElement>>> list;
return list;
}
static bool mutationObserverCompoundMicrotaskQueuedFlag;
class MutationObserverMicrotask final : public Microtask {
WTF_MAKE_FAST_ALLOCATED;
private:
Result run() final
{
MutationObserver::notifyMutationObservers();
return Result::Done;
}
};
static void queueMutationObserverCompoundMicrotask()
{
if (mutationObserverCompoundMicrotaskQueuedFlag)
return;
mutationObserverCompoundMicrotaskQueuedFlag = true;
MicrotaskQueue::mainThreadQueue().append(std::make_unique<MutationObserverMicrotask>());
}
void MutationObserver::enqueueMutationRecord(Ref<MutationRecord>&& mutation)
{
ASSERT(isMainThread());
m_records.append(WTFMove(mutation));
activeMutationObservers().add(this);
queueMutationObserverCompoundMicrotask();
}
void MutationObserver::enqueueSlotChangeEvent(HTMLSlotElement& slot)
{
ASSERT(isMainThread());
ASSERT(!signalSlotList().contains(&slot));
signalSlotList().append(&slot);
queueMutationObserverCompoundMicrotask();
}
void MutationObserver::setHasTransientRegistration()
{
ASSERT(isMainThread());
activeMutationObservers().add(this);
queueMutationObserverCompoundMicrotask();
}
HashSet<Node*> MutationObserver::observedNodes() const
{
HashSet<Node*> observedNodes;
for (auto* registration : m_registrations)
registration->addRegistrationNodesToSet(observedNodes);
return observedNodes;
}
bool MutationObserver::canDeliver()
{
return m_callback->canInvokeCallback();
}
void MutationObserver::deliver()
{
ASSERT(canDeliver());
Vector<MutationObserverRegistration*, 1> transientRegistrations;
for (auto* registration : m_registrations) {
if (registration->hasTransientRegistrations())
transientRegistrations.append(registration);
}
for (auto& registration : transientRegistrations)
registration->clearTransientRegistrations();
if (m_records.isEmpty())
return;
Vector<Ref<MutationRecord>> records;
records.swap(m_records);
m_callback->call(records, this);
}
void MutationObserver::notifyMutationObservers()
{
mutationObserverCompoundMicrotaskQueuedFlag = false;
ASSERT(isMainThread());
static bool deliveryInProgress = false;
if (deliveryInProgress)
return;
deliveryInProgress = true;
if (!suspendedMutationObservers().isEmpty()) {
Vector<RefPtr<MutationObserver>> suspended;
copyToVector(suspendedMutationObservers(), suspended);
for (auto& observer : suspended) {
if (!observer->canDeliver())
continue;
suspendedMutationObservers().remove(observer);
activeMutationObservers().add(observer);
}
}
while (!activeMutationObservers().isEmpty() || !signalSlotList().isEmpty()) {
Vector<RefPtr<MutationObserver>> notifyList;
copyToVector(activeMutationObservers(), notifyList);
activeMutationObservers().clear();
std::sort(notifyList.begin(), notifyList.end(), [](auto& lhs, auto& rhs) {
return lhs->m_priority < rhs->m_priority;
});
Vector<RefPtr<HTMLSlotElement>> slotList;
if (!signalSlotList().isEmpty()) {
slotList.swap(signalSlotList());
for (auto& slot : slotList)
slot->didRemoveFromSignalSlotList();
}
for (auto& observer : notifyList) {
if (observer->canDeliver())
observer->deliver();
else
suspendedMutationObservers().add(observer);
}
for (auto& slot : slotList)
slot->dispatchSlotChangeEvent();
}
deliveryInProgress = false;
}
}