Source/WebCore/dom/WebKitMutationObserver.cpp

/*
 * Copyright (C) 2011 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions are
 * met:
 *
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 * notice, this list of conditions and the following disclaimer.
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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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#include "config.h"

#if ENABLE(MUTATION_OBSERVERS)

#include "WebKitMutationObserver.h"

#include "Document.h"
#include "ExceptionCode.h"
#include "MutationCallback.h"
#include "MutationObserverRegistration.h"
#include "MutationRecord.h"
#include "Node.h"
#include <algorithm>
#include <wtf/HashSet.h>
#include <wtf/MainThread.h>
#include <wtf/Vector.h>

namespace WebCore {

static unsigned s_observerPriority = 0;

struct WebKitMutationObserver::ObserverLessThan {
    bool operator()(const RefPtr<WebKitMutationObserver>& lhs, const RefPtr<WebKitMutationObserver>& rhs)
    {
        return lhs->m_priority < rhs->m_priority;
    }
};

PassRefPtr<WebKitMutationObserver> WebKitMutationObserver::create(PassRefPtr<MutationCallback> callback)
{
    ASSERT(isMainThread());
    return adoptRef(new WebKitMutationObserver(callback));
}

WebKitMutationObserver::WebKitMutationObserver(PassRefPtr<MutationCallback> callback)
    : m_callback(callback)
    , m_priority(s_observerPriority++)
{
}

WebKitMutationObserver::~WebKitMutationObserver()
{
    ASSERT(m_registrations.isEmpty());
}

bool WebKitMutationObserver::validateOptions(MutationObserverOptions options)
{
    return (options & (Attributes | CharacterData | ChildList))
        && ((options & Attributes) || !(options & AttributeOldValue))
        && ((options & Attributes) || !(options & AttributeFilter))
        && ((options & CharacterData) || !(options & CharacterDataOldValue));
}

void WebKitMutationObserver::observe(Node* node, MutationObserverOptions options, const HashSet<AtomicString>& attributeFilter, ExceptionCode& ec)
{
    if (!node) {
        ec = NOT_FOUND_ERR;
        return;
    }

    if (!validateOptions(options)) {
        // FIXME: Revisit this once the spec specifies the exception type; SYNTAX_ERR may not be appropriate.
        ec = SYNTAX_ERR;
        return;
    }

    MutationObserverRegistration* registration = node->registerMutationObserver(this);
    registration->resetObservation(options, attributeFilter);

    node->document()->addMutationObserverTypes(registration->mutationTypes());
}

Vector<RefPtr<MutationRecord> > WebKitMutationObserver::takeRecords()
{
    Vector<RefPtr<MutationRecord> > records;
    records.swap(m_records);
    return records;
}

void WebKitMutationObserver::disconnect()
{
    m_records.clear();
    HashSet<MutationObserverRegistration*> registrations(m_registrations);
    for (HashSet<MutationObserverRegistration*>::iterator iter = registrations.begin(); iter != registrations.end(); ++iter)
        (*iter)->unregister();
}

void WebKitMutationObserver::observationStarted(MutationObserverRegistration* registration)
{
    ASSERT(!m_registrations.contains(registration));
    m_registrations.add(registration);
}

void WebKitMutationObserver::observationEnded(MutationObserverRegistration* registration)
{
    ASSERT(m_registrations.contains(registration));
    m_registrations.remove(registration);
}

typedef HashSet<RefPtr<WebKitMutationObserver> > MutationObserverSet;

static MutationObserverSet& activeMutationObservers()
{
    DEFINE_STATIC_LOCAL(MutationObserverSet, activeObservers, ());
    return activeObservers;
}

void WebKitMutationObserver::enqueueMutationRecord(PassRefPtr<MutationRecord> mutation)
{
    ASSERT(isMainThread());
    m_records.append(mutation);
    activeMutationObservers().add(this);
}

void WebKitMutationObserver::setHasTransientRegistration()
{
    ASSERT(isMainThread());
    activeMutationObservers().add(this);
}

void WebKitMutationObserver::deliver()
{
    // Calling clearTransientRegistrations() can modify m_registrations, so it's necessary
    // to make a copy of the transient registrations before operating on them.
    Vector<MutationObserverRegistration*, 1> transientRegistrations;
    for (HashSet<MutationObserverRegistration*>::iterator iter = m_registrations.begin(); iter != m_registrations.end(); ++iter) {
        if ((*iter)->hasTransientRegistrations())
            transientRegistrations.append(*iter);
    }
    for (size_t i = 0; i < transientRegistrations.size(); ++i)
        transientRegistrations[i]->clearTransientRegistrations();

    if (m_records.isEmpty())
        return;

    Vector<RefPtr<MutationRecord> > records;
    records.swap(m_records);

    m_callback->handleEvent(&records, this);
}

void WebKitMutationObserver::deliverAllMutations()
{
    ASSERT(isMainThread());
    static bool deliveryInProgress = false;
    if (deliveryInProgress)
        return;
    deliveryInProgress = true;

    while (!activeMutationObservers().isEmpty()) {
        Vector<RefPtr<WebKitMutationObserver> > observers;
        copyToVector(activeMutationObservers(), observers);
        activeMutationObservers().clear();
        std::sort(observers.begin(), observers.end(), ObserverLessThan());
        for (size_t i = 0; i < observers.size(); ++i)
            observers[i]->deliver();
    }

    deliveryInProgress = false;
}

} // namespace WebCore

#endif // ENABLE(MUTATION_OBSERVERS)