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/*
* Copyright (C) 2011 Google Inc. All rights reserved.
* Copyright (C) 2018-2022 Apple 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
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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
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "MutationObserver.h"
#include "Document.h"
#include "GCReachableRef.h"
#include "HTMLSlotElement.h"
#include "InspectorInstrumentation.h"
#include "MutationCallback.h"
#include "MutationObserverRegistration.h"
#include "MutationRecord.h"
#include "WindowEventLoop.h"
#include <algorithm>
#include <wtf/IsoMallocInlines.h>
#include <wtf/MainThread.h>
#include <wtf/NeverDestroyed.h>
#include <wtf/RobinHoodHashSet.h>
namespace WebCore {
WTF_MAKE_ISO_ALLOCATED_IMPL(MutationObserver);
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.computesEmpty());
}
bool MutationObserver::validateOptions(MutationObserverOptions options)
{
return options.containsAny(AllMutationTypes)
&& (options.contains(OptionType::Attributes) || !options.contains(OptionType::AttributeOldValue))
&& (options.contains(OptionType::Attributes) || !options.contains(OptionType::AttributeFilter))
&& (options.contains(OptionType::CharacterData) || !options.contains(OptionType::CharacterDataOldValue));
}
ExceptionOr<void> MutationObserver::observe(Node& node, const Init& init)
{
MutationObserverOptions options;
if (init.childList)
options.add(OptionType::ChildList);
if (init.subtree)
options.add(OptionType::Subtree);
if (init.attributeOldValue.value_or(false))
options.add(OptionType::AttributeOldValue);
if (init.characterDataOldValue.value_or(false))
options.add(OptionType::CharacterDataOldValue);
MemoryCompactLookupOnlyRobinHoodHashSet<AtomString> attributeFilter;
if (init.attributeFilter) {
for (auto& value : init.attributeFilter.value())
attributeFilter.add(value);
options.add(OptionType::AttributeFilter);
}
if (init.attributes ? init.attributes.value() : options.containsAny({ OptionType::AttributeFilter, OptionType::AttributeOldValue }))
options.add(OptionType::Attributes);
if (init.characterData ? init.characterData.value() : options.contains(OptionType::CharacterDataOldValue))
options.add(OptionType::CharacterData);
if (!validateOptions(options))
return Exception { TypeError };
node.registerMutationObserver(*this, options, attributeFilter);
return { };
}
auto MutationObserver::takeRecords() -> TakenRecords
{
return { WTFMove(m_records), WTFMove(m_pendingTargets) };
}
void MutationObserver::disconnect()
{
m_pendingTargets.clear();
m_records.clear();
WeakHashSet registrations { m_registrations };
for (auto& registration : registrations) {
Ref nodeRef { registration.node() };
nodeRef->unregisterMutationObserver(registration);
}
}
void MutationObserver::observationStarted(MutationObserverRegistration& registration)
{
ASSERT(!m_registrations.contains(registration));
m_registrations.add(registration);
}
void MutationObserver::observationEnded(MutationObserverRegistration& registration)
{
ASSERT(m_registrations.contains(registration));
m_registrations.remove(registration);
}
void MutationObserver::enqueueMutationRecord(Ref<MutationRecord>&& mutation)
{
ASSERT(isMainThread());
ASSERT(mutation->target());
Ref document = mutation->target()->document();
m_pendingTargets.add(*mutation->target());
m_records.append(WTFMove(mutation));
Ref eventLoop = document->windowEventLoop();
eventLoop->activeMutationObservers().add(this);
eventLoop->queueMutationObserverCompoundMicrotask();
}
void MutationObserver::enqueueSlotChangeEvent(HTMLSlotElement& slot)
{
ASSERT(isMainThread());
Ref eventLoop = slot.document().windowEventLoop();
auto& list = eventLoop->signalSlotList();
ASSERT(list.findIf([&slot](auto& entry) { return entry.ptr() == &slot; }) == notFound);
list.append(slot);
eventLoop->queueMutationObserverCompoundMicrotask();
}
void MutationObserver::setHasTransientRegistration(Document& document)
{
Ref eventLoop = document.windowEventLoop();
eventLoop->activeMutationObservers().add(this);
eventLoop->queueMutationObserverCompoundMicrotask();
}
bool MutationObserver::isReachableFromOpaqueRoots(JSC::AbstractSlotVisitor& visitor) const
{
for (auto& registration : m_registrations) {
if (registration.isReachableFromOpaqueRoots(visitor))
return true;
}
return false;
}
bool MutationObserver::canDeliver()
{
return m_callback->canInvokeCallback();
}
void MutationObserver::deliver()
{
ASSERT(canDeliver());
// Calling takeTransientRegistrations() can modify m_registrations, so it's necessary
// to make a copy of the transient registrations before operating on them.
Vector<MutationObserverRegistration*, 1> transientRegistrations;
Vector<HashSet<GCReachableRef<Node>>, 1> nodesToKeepAlive;
HashSet<GCReachableRef<Node>> pendingTargets;
pendingTargets.swap(m_pendingTargets);
for (auto& registration : m_registrations) {
if (registration.hasTransientRegistrations())
transientRegistrations.append(&registration);
}
for (auto& registration : transientRegistrations)
nodesToKeepAlive.append(registration->takeTransientRegistrations());
if (m_records.isEmpty()) {
ASSERT(m_pendingTargets.isEmpty());
return;
}
Vector<Ref<MutationRecord>> records;
records.swap(m_records);
// FIXME: Keep mutation observer callback as long as its observed nodes are alive. See https://webkit.org/b/179224.
if (m_callback->hasCallback()) {
auto* context = m_callback->scriptExecutionContext();
if (!context)
return;
InspectorInstrumentation::willFireObserverCallback(*context, "MutationObserver"_s);
m_callback->handleEvent(*this, records, *this);
InspectorInstrumentation::didFireObserverCallback(*context);
}
}
// https://dom.spec.whatwg.org/#notify-mutation-observers
void MutationObserver::notifyMutationObservers(WindowEventLoop& eventLoop)
{
if (!eventLoop.suspendedMutationObservers().isEmpty()) {
for (auto& observer : copyToVector(eventLoop.suspendedMutationObservers())) {
if (!observer->canDeliver())
continue;
eventLoop.suspendedMutationObservers().remove(observer);
eventLoop.activeMutationObservers().add(observer);
}
}
while (!eventLoop.activeMutationObservers().isEmpty() || !eventLoop.signalSlotList().isEmpty()) {
// 2. Let notify list be a copy of unit of related similar-origin browsing contexts' list of MutationObserver objects.
auto notifyList = copyToVector(eventLoop.activeMutationObservers());
eventLoop.activeMutationObservers().clear();
std::sort(notifyList.begin(), notifyList.end(), [](auto& lhs, auto& rhs) {
return lhs->m_priority < rhs->m_priority;
});
// 3. Let signalList be a copy of unit of related similar-origin browsing contexts' signal slot list.
// 4. Empty unit of related similar-origin browsing contexts' signal slot list.
Vector<GCReachableRef<HTMLSlotElement>> slotList;
if (!eventLoop.signalSlotList().isEmpty()) {
slotList.swap(eventLoop.signalSlotList());
for (auto& slot : slotList)
slot->didRemoveFromSignalSlotList();
}
// 5. For each MutationObserver object mo in notify list, execute a compound microtask subtask
for (auto& observer : notifyList) {
if (observer->canDeliver())
observer->deliver();
else
eventLoop.suspendedMutationObservers().add(observer);
}
// 6. For each slot slot in signalList, in order, fire an event named slotchange, with its bubbles attribute set to true, at slot.
for (auto& slot : slotList)
slot->dispatchSlotChangeEvent();
}
}
} // namespace WebCore