/*
 * This file is part of the DOM implementation for KDE.
 * Copyright (C) 2005, 2006 Apple Computer, Inc.
 * Copyright (C) 2002 Lars Knoll <knoll@kde.org>
 *
 * 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 SHARED_H
#define SHARED_H

#include <wtf/SharedPtr.h>

namespace khtml
{

template<class type> class Shared
{
public:
    Shared()
    {
        _ref = 0; /*counter++;*/
    }
    ~Shared()
    {
        /*counter--;*/
    }

    void ref()
    {
        _ref++;
    }
    void deref()
    {
        if (_ref) {
            _ref--;
        }
        if (!_ref) {
            delete static_cast<type *>(this);
        }
    }
    bool hasOneRef()   //qDebug() << "ref=" << _ref;
    {
        return _ref == 1;
    }

    int refCount() const
    {
        return _ref;
    }
//    static int counter;
protected:
    unsigned int _ref;

private:
    //Avoid the automatic copy constructor
    Shared(const Shared &);
    Shared &operator= (const Shared &);
};

template<class type> class TreeShared
{
public:
    TreeShared()
    {
        _ref = 0;
        m_parent = 0; /*counter++;*/
    }
    TreeShared(type *parent)
    {
        _ref = 0;
        m_parent = parent; /*counter++;*/
    }
    virtual ~TreeShared()
    {
        /*counter--;*/
    }

    virtual void removedLastRef()
    {
        delete static_cast<type *>(this);
    }

    void ref()
    {
        _ref++;
    }
    void deref()
    {
        if (_ref) {
            _ref--;
        }
        if (!_ref && !m_parent) {
            removedLastRef();
        }
    }

    // This method decreases the reference count, but never deletes the object.
    // It should be used when a method may be passed something with the initial
    // reference count of 0, but still needs to guard it.
    void derefOnly()
    {
        _ref--;
    }

    bool hasOneRef()   //qDebug() << "ref=" << _ref;
    {
        return _ref == 1;
    }

    int refCount() const
    {
        return _ref;
    }
//    static int counter;

    void setParent(type *parent)
    {
        m_parent = parent;
    }
    type *parent() const
    {
        return m_parent;
    }
private:
    //Avoid the automatic copy constructor
    TreeShared(const TreeShared &);
    TreeShared &operator= (const TreeShared &);

    unsigned int _ref;
protected:
    type *m_parent;
};

//A special pointer for nodes keeping track of the document,
//which helps distinguish back links from them to it, in order to break
//cycles
template <class T> class DocPtr
{
public:
    DocPtr() : m_ptr(0) {}
    DocPtr(T *ptr) : m_ptr(ptr)
    {
        if (ptr) {
            ptr->selfOnlyRef();
        }
    }
    DocPtr(const DocPtr &o) : m_ptr(o.m_ptr)
    {
        if (T *ptr = m_ptr) {
            ptr->selfOnlyRef();
        }
    }
    ~DocPtr()
    {
        if (T *ptr = m_ptr) {
            ptr->selfOnlyDeref();
        }
    }

    template <class U> DocPtr(const DocPtr<U> &o) : m_ptr(o.get())
    {
        if (T *ptr = m_ptr) {
            ptr->selfOnlyRef();
        }
    }

    void resetSkippingRef(T *o)
    {
        m_ptr = o;
    }

    T *get() const
    {
        return m_ptr;
    }

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

    bool operator!() const
    {
        return !m_ptr;
    }

    // this type conversion operator allows implicit conversion to
    // bool but not to other integer types

    typedef T *(DocPtr::*UnspecifiedBoolType)() const;
    operator UnspecifiedBoolType() const
    {
        return m_ptr ? &DocPtr::get : 0;
    }

    DocPtr &operator=(const DocPtr &);
    DocPtr &operator=(T *);

private:
    T *m_ptr;
};

template <class T> DocPtr<T> &DocPtr<T>::operator=(const DocPtr<T> &o)
{
    T *optr = o.m_ptr;
    if (optr) {
        optr->selfOnlyRef();
    }
    if (T *ptr = m_ptr) {
        ptr->selfOnlyDeref();
    }
    m_ptr = optr;
    return *this;
}

template <class T> inline DocPtr<T> &DocPtr<T>::operator=(T *optr)
{
    if (optr) {
        optr->selfOnlyRef();
    }
    if (T *ptr = m_ptr) {
        ptr->selfOnlyDeref();
    }
    m_ptr = optr;
    return *this;
}

template <class T> inline bool operator==(const DocPtr<T> &a, const DocPtr<T> &b)
{
    return a.get() == b.get();
}

template <class T> inline bool operator==(const DocPtr<T> &a, const T *b)
{
    return a.get() == b;
}

template <class T> inline bool operator==(const T *a, const DocPtr<T> &b)
{
    return a == b.get();
}

template <class T> inline bool operator!=(const DocPtr<T> &a, const DocPtr<T> &b)
{
    return a.get() != b.get();
}

template <class T> inline bool operator!=(const DocPtr<T> &a, const T *b)
{
    return a.get() != b;
}

template <class T> inline bool operator!=(const T *a, const DocPtr<T> &b)
{
    return a != b.get();
}

} // namespace

#endif
