WebCore/rendering/DataRef.h

/*
 * This file is part of the DOM implementation for KDE.
 *
 * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
 *           (C) 2000 Antti Koivisto (koivisto@kde.org)
 *           (C) 2000 Dirk Mueller (mueller@kde.org)
 * Copyright (C) 2003, 2005 Apple Computer, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 */

#ifndef DataRef_h
#define DataRef_h

namespace WebCore {

template <typename T> class DataRef {
public:
    DataRef()
        : m_data(0)
    {
    }

    DataRef(const DataRef<T>& d)
    {
        ASSERT(d.m_data);
        m_data = d.m_data;
        m_data->ref();
    }

    ~DataRef()
    {
        if (m_data)
            m_data->deref();
    }

    const T* get() const { return m_data; }

    T& operator*() const { return *m_data; }
    const T* operator->() const { return m_data; }

    T* access()
    {
        if (!m_data->hasOneRef()) {
            m_data->deref();
            m_data = new T(*m_data);
            m_data->ref();
        }
        return m_data;
    }

    void init()
    {
        ASSERT(!m_data);
        m_data = new T;
        m_data->ref();
    }

    DataRef<T>& operator=(const DataRef<T>& d)
    {
        ASSERT(d.m_data);
        d.m_data->ref();
        if (m_data)
            m_data->deref();
        m_data = d.m_data;
        return *this;
    }

    bool operator==(const DataRef<T>& o) const
    {
        ASSERT(m_data);
        ASSERT(o.m_data);
        return m_data == o.m_data || *m_data == *o.m_data;
    }
    
    bool operator!=(const DataRef<T>& o) const
    {
        ASSERT(m_data);
        ASSERT(o.m_data);
        return m_data != o.m_data && *m_data != *o.m_data;
    }

private:
    T* m_data;
};

} // namespace WebCore

#endif // DataRef_h