/*

 * Copyright (C) 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.

 *

 * 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 RefCounted_h

#define RefCounted_h

#include "Assertions.h"

#include "Noncopyable.h"

namespace WTF {

// This base class holds the non-template methods and attributes.

// The RefCounted class inherits from it reducing the template bloat

// generated by the compiler (technique called template hoisting).

class RefCountedBase {

public:

    void ref()

    {

        ASSERT(!m_deletionHasBegun);

        ASSERT(!m_adoptionIsRequired);

        ++m_refCount;

    }

    bool hasOneRef() const

    {

        ASSERT(!m_deletionHasBegun);

        return m_refCount == 1;

    }

    int refCount() const

    {

        return m_refCount;

    }

    void relaxAdoptionRequirement()

    {

#ifndef NDEBUG

        ASSERT(!m_deletionHasBegun);

        ASSERT(m_adoptionIsRequired);

        m_adoptionIsRequired = false;

#endif

    }

protected:

    RefCountedBase()

        : m_refCount(1)

#ifndef NDEBUG

        , m_deletionHasBegun(false)

        , m_adoptionIsRequired(true)

#endif

    {

    }

    ~RefCountedBase()

    {

        ASSERT(m_deletionHasBegun);

        ASSERT(!m_adoptionIsRequired);

    }

    // Returns whether the pointer should be freed or not.

    bool derefBase()

    {

        ASSERT(!m_deletionHasBegun);

        ASSERT(!m_adoptionIsRequired);

        ASSERT(m_refCount > 0);

        if (m_refCount == 1) {

#ifndef NDEBUG

            m_deletionHasBegun = true;

#endif

            return true;

        }

        --m_refCount;

        return false;

    }

    // Helper for generating JIT code. Please do not use for non-JIT purposes.

    int* addressOfCount()

    {

        return &m_refCount;

    }

#ifndef NDEBUG

    bool deletionHasBegun() const

    {

        return m_deletionHasBegun;

    }

#endif

private:

    template<typename T> friend class CrossThreadRefCounted;

#ifndef NDEBUG

    friend void adopted(RefCountedBase*);

#endif

    int m_refCount;

#ifndef NDEBUG

    bool m_deletionHasBegun;

    bool m_adoptionIsRequired;

#endif

};

#ifndef NDEBUG

inline void adopted(RefCountedBase* object)

{

    if (!object)

        return;

    ASSERT(!object->m_deletionHasBegun);

    object->m_adoptionIsRequired = false;

}

#endif

template<typename T> class RefCounted : public RefCountedBase, public Noncopyable {

public:

    void deref()

    {

        if (derefBase())

            delete static_cast<T*>(this);

    }

protected:

    ~RefCounted()

    {

    }

};

template<typename T> class RefCountedCustomAllocated : public RefCountedBase, public NoncopyableCustomAllocated {

public:

    void deref()

    {

        if (derefBase())

            delete static_cast<T*>(this);

    }

protected:

    ~RefCountedCustomAllocated()

    {

    }

};

} // namespace WTF

using WTF::RefCounted;

using WTF::RefCountedCustomAllocated;

#endif // RefCounted_h