common/ref_object.hpp

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//
// See license.txt for license information.
//
// ref_object.hpp
//
// 4-Jul-2003  phamilton  Created
//

#ifndef incCOMMON_REF_OBJECT
#define incCOMMON_REF_OBJECT

// forwards
#include "object.hpp"
#include "deletable_object.hpp"
#include "outerable_object.hpp"

namespace ph {
namespace common {

class ref_object_helper
/**
        Helper for an object which refers to another.
*/
{
public:
        ref_object_helper() :
                _obj(0)
                        {}
                        
        void helper_delete_object(bool owned)
        /**
                Delete the object attached. Only deletes if the
                object is actually owned by this.
        */
        {
                // only delete sub objects if this is owned.
                if (owned)
                {
                        // if the object has a delete interface, then use that.
                        if (_obj->deletable())
                                _obj->deletable()->delete_object();
                        else
                                delete _obj;
                }
                else
                        helper_remove(_obj);
        }
        
        bool helper_add(object_base *parent, 
                        object_base *obj, bool own, bool owned)
        /**
                Add a new object to the reference.
        */
        {
                // ownership policies must match.
                // you also can't already have an object.
                if (_obj || own != owned)
                        return false;
                if (obj->outerable())
                        obj->outerable()->outer(parent);
                _obj = obj;     
                return true;
        }
        
        bool helper_remove(object_base *obj)
        /**
                remove an object from the reference.
        */
        {
                if (!_obj || obj != _obj)
                        return false;
                _obj = 0;               
                return true;
        }
        
        bool helper_singleton() const
        /**
                References are singleton objects.
        */
        {
                return true;
        }
        
        bool helper_count() const
        /**
                Return the number of objects in the reference.
        */
        {
                return _obj ? 1 : 0;
        }
        
protected:
        object_base *_obj;
};

}; // common
}; // ph

#endif // incCOMMON_REF_OBJECT

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