OpenSceneGraph/include/osg/ref_ptr

/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2005 Robert Osfield 
 *
 * This library is open source and may be redistributed and/or modified under  
 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or 
 * (at your option) any later version.  The full license is in LICENSE file
 * included with this distribution, and on the openscenegraph.org website.
 * 
 * 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 
 * OpenSceneGraph Public License for more details.
*/

#ifndef OSG_REF_PTR
#define OSG_REF_PTR 1

namespace osg {

/** Smart pointer for handling referenced counted objects.*/
template<class T>
class ref_ptr
{

    public:
        typedef T element_type;

        ref_ptr() :_ptr(0L) {}
        ref_ptr(T* t):_ptr(t)              { if (_ptr) _ptr->ref(); }
        ref_ptr(const ref_ptr& rp):_ptr(rp._ptr)  { if (_ptr) _ptr->ref(); }
        ~ref_ptr()                           { if (_ptr) _ptr->unref(); _ptr=0; }

        inline ref_ptr& operator = (const ref_ptr& rp)
        {
            if (_ptr==rp._ptr) return *this;
            T* tmp_ptr = _ptr;
            _ptr = rp._ptr;
            if (_ptr) _ptr->ref();
            // unref second to prevent any deletion of any object which might
            // be referenced by the other object. i.e rp is child of the
            // original _ptr.
            if (tmp_ptr) tmp_ptr->unref();
            return *this;
        }

        inline ref_ptr& operator = (T* ptr)
        {
            if (_ptr==ptr) return *this;
            T* tmp_ptr = _ptr;
            _ptr = ptr;
            if (_ptr) _ptr->ref();
            // unref second to prevent any deletion of any object which might
            // be referenced by the other object. i.e rp is child of the
            // original _ptr.
            if (tmp_ptr) tmp_ptr->unref();
            return *this;
        }

        // comparison operators for ref_ptr.
        inline bool operator == (const ref_ptr& rp) const { return (_ptr==rp._ptr); }
        inline bool operator != (const ref_ptr& rp) const { return (_ptr!=rp._ptr); }
        inline bool operator < (const ref_ptr& rp) const { return (_ptr<rp._ptr); }
        inline bool operator > (const ref_ptr& rp) const { return (_ptr>rp._ptr); }

        // comparison operator for const T*.
        inline bool operator == (const T* ptr) const { return (_ptr==ptr); }
        inline bool operator != (const T* ptr) const { return (_ptr!=ptr); }
        inline bool operator < (const T* ptr) const { return (_ptr<ptr); }
        inline bool operator > (const T* ptr) const { return (_ptr>ptr); }


        inline T& operator*()  { return *_ptr; }

        inline const T& operator*() const { return *_ptr; }

        inline T* operator->() { return _ptr; }

        inline const T* operator->() const   { return _ptr; }

        inline bool operator!() const   { return _ptr==0L; }

        inline bool valid() const       { return _ptr!=0L; }
        
        inline T* get() { return _ptr; }

        inline const T* get() const { return _ptr; }

        /** take control over the object pointed to by ref_ptr, unreference but do not delete even if ref count goes to 0,
          * return the pointer to the object.
          * Note, do not use this unless you are 100% sure your code handles the deletion of the object correctly, and
          * only use when absolutely required.*/
        inline T* take() { return release();}

        inline T* release() { T* tmp=_ptr; if (_ptr) _ptr->unref_nodelete(); _ptr=0; return tmp;}

    private:
        T* _ptr;
};

}

#endif