Source/WebCore/dom/ScopedEventQueue.h

/*
 * Copyright (C) 2010 Google Inc. All rights reserved.
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 * 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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 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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#pragma once

#include <wtf/Forward.h>
#include <wtf/Noncopyable.h>
#include <wtf/Ref.h>
#include <wtf/Vector.h>

namespace WebCore {

class Event;
class EventQueueScope;

class ScopedEventQueue {
    WTF_MAKE_NONCOPYABLE(ScopedEventQueue); WTF_MAKE_FAST_ALLOCATED;
public:
    static ScopedEventQueue& singleton();
    void enqueueEvent(Ref<Event>&&);

private:
    ScopedEventQueue() = default;
    ~ScopedEventQueue() = delete;

    void dispatchEvent(Event&) const;
    void dispatchAllEvents();
    void incrementScopingLevel();
    void decrementScopingLevel();

    Vector<Ref<Event>> m_queuedEvents;
    unsigned m_scopingLevel { 0 };

    friend class WTF::NeverDestroyed<WebCore::ScopedEventQueue>;
    friend class EventQueueScope;
};

class EventQueueScope {
    WTF_MAKE_NONCOPYABLE(EventQueueScope);
public:
    EventQueueScope() { ScopedEventQueue::singleton().incrementScopingLevel(); }
    ~EventQueueScope() { ScopedEventQueue::singleton().decrementScopingLevel(); }
};

} // namespace WebCore