Source/WebCore/platform/Supplementable.h

/*
 * Copyright (C) 2012 Google, 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:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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 distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef Supplementable_h
#define Supplementable_h

#include <wtf/HashMap.h>
#include <wtf/PassOwnPtr.h>
#include <wtf/text/AtomicString.h>
#include <wtf/text/AtomicStringHash.h>

namespace WebCore {

template<typename T>
class Supplementable;

template<typename T>
class Supplement {
public:
    virtual ~Supplement() { }
#if !ASSERT_DISABLED
    virtual bool isRefCountedWrapper() const { return false; }
#endif

    static void provideTo(Supplementable<T>* host, const AtomicString& key, PassOwnPtr<Supplement<T> > supplement)
    {
        host->provideSupplement(key, supplement);
    }

    static Supplement<T>* from(Supplementable<T>* host, const AtomicString& key)
    {
        return host ? host->requireSupplement(key) : 0;
    }
};

template<typename T>
class Supplementable {
public:
    void provideSupplement(const AtomicString& key, PassOwnPtr<Supplement<T> > supplement)
    {
        ASSERT(!m_supplements.get(key.impl()));
        m_supplements.set(key, supplement);
    }

    void removeSupplement(const AtomicString& key)
    {
        m_supplements.remove(key);
    }

    Supplement<T>* requireSupplement(const AtomicString& key)
    {
        return m_supplements.get(key);
    }

private:
    typedef HashMap<AtomicString, OwnPtr<Supplement<T> > > SupplementMap;
    SupplementMap m_supplements;
};

} // namespace WebCore

#endif // Supplementable_h