kdelibs/khtml/misc/shared.h

/*
 * 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() { //kDebug(6000) << "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() { //kDebug(6000) << "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