Reference.h

Go to the documentation of this file.

/*
* This file is part of Project SkyFire https://www.projectskyfire.org.
* See LICENSE.md file for Copyright information
*/
 
#ifndef _REFERENCE_H
#define _REFERENCE_H
 
#include "Dynamic/LinkedList.h"
#include "Errors.h" // for ASSERT
 
//=====================================================
 
template <class TO, class FROM> class Reference : public LinkedListElement
{
private:
    TO* iRefTo;
    FROM* iRefFrom;
protected:
    // Tell our refTo (target) object that we have a link
    virtual void targetObjectBuildLink() = 0;
 
    // Tell our refTo (taget) object, that the link is cut
    virtual void targetObjectDestroyLink() = 0;
 
    // Tell our refFrom (source) object, that the link is cut (Target destroyed)
    virtual void sourceObjectDestroyLink() = 0;
public:
    Reference() { iRefTo = NULL; iRefFrom = NULL; }
    virtual ~Reference() { }
 
    // Create new link
    void link(TO* toObj, FROM* fromObj)
    {
        ASSERT(fromObj);                                // fromObj MUST not be NULL
        if (isValid())
            unlink();
        if (toObj != NULL)
        {
            iRefTo = toObj;
            iRefFrom = fromObj;
            targetObjectBuildLink();
        }
    }
 
    // We don't need the reference anymore. Call comes from the refFrom object
    // Tell our refTo object, that the link is cut
    void unlink()
    {
        targetObjectDestroyLink();
        delink();
        iRefTo = NULL;
        iRefFrom = NULL;
    }
 
    // Link is invalid due to destruction of referenced target object. Call comes from the refTo object
    // Tell our refFrom object, that the link is cut
    void invalidate()                                   // the iRefFrom MUST remain!!
    {
        sourceObjectDestroyLink();
        delink();
        iRefTo = NULL;
    }
 
    bool isValid() const                                // Only check the iRefTo
    {
        return iRefTo != NULL;
    }
 
    Reference<TO, FROM>* next() { return((Reference<TO, FROM>       *) LinkedListElement::next()); }
    Reference<TO, FROM> const* next() const { return((Reference<TO, FROM> const*) LinkedListElement::next()); }
    Reference<TO, FROM>* prev() { return((Reference<TO, FROM>       *) LinkedListElement::prev()); }
    Reference<TO, FROM> const* prev() const { return((Reference<TO, FROM> const*) LinkedListElement::prev()); }
 
    Reference<TO, FROM>* nocheck_next() { return((Reference<TO, FROM>       *) LinkedListElement::nocheck_next()); }
    Reference<TO, FROM> const* nocheck_next() const { return((Reference<TO, FROM> const*) LinkedListElement::nocheck_next()); }
    Reference<TO, FROM>* nocheck_prev() { return((Reference<TO, FROM>       *) LinkedListElement::nocheck_prev()); }
    Reference<TO, FROM> const* nocheck_prev() const { return((Reference<TO, FROM> const*) LinkedListElement::nocheck_prev()); }
 
    TO* operator ->() const { return iRefTo; }
    TO* getTarget() const { return iRefTo; }
 
    FROM* GetSource() const { return iRefFrom; }
private:
    Reference(Reference const&);
    Reference& operator=(Reference const&);
};
 
//=====================================================
#endif