/*

* Copyright (c) 2008-2009 Nokia Corporation and/or its subsidiary(-ies). 

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description:    Type-safe unique id template

*

*/

#ifndef T_GLXID_H

#define T_GLXID_H

#include "e32std.h"

#include "glxpanic.h"

/** Invalid or undefined id value */

// Use "id == KGlxIdNone" and "id != KGlxIdNone" to check for

// id validity.

class TGlxIdNone {};

const TGlxIdNone KGlxIdNone = TGlxIdNone();

/**

 *  TGlxId

 *

 *  Type-safe template for ids

 *  Id value of KMaxTUint is consided to be undefined.

 *  @usage Define like this:

 *            class TMyIdBase {}; 

 *            typedef TGlxId<TMyIdBase> TMyId;

 *            Now use can use TMyId in other code

 */

template <class T> 

class TGlxId : public T {

public:

    inline TGlxId(); 

    inline TGlxId(const TGlxId<T>& aId);

    inline TGlxId(TUint aIdValue); 

    inline TGlxId(const TGlxIdNone&);

    inline TGlxId<T>& operator=(const TGlxId<T>& aId);

    inline TGlxId<T>& operator=(TUint aIdValue);

    inline TGlxId<T>& operator=(const TGlxIdNone&);

    inline TGlxId<T> operator++(int); // Postfix, keep dummy parameter as int

    inline TBool operator!=(const TGlxId<T>& aId) const;

    inline TBool operator==(const TGlxId<T>& aId) const;

    inline TBool operator!=(const TGlxIdNone&) const;

    inline TBool operator==(const TGlxIdNone&) const;

    inline TBool operator>(const TGlxId<T>& aId) const;

    inline TBool operator<(const TGlxId<T>& aId) const;

    inline TUint Value() const;

    inline void SetValue(TUint aIdValue); // Allows setting undefined as value (KMaxTUint)

private:

    TUint iIdValue;

};

/**

 * MGlxIdProvider

 * Abstract interface class to provide ids 

 * Define as MGlxIdProvider<TMyId>

 */ 

template <class T>

class MGlxIdProvider {

public:

    /**

     * getNextId

     * Returns the next unique id.

     * Returns value in the argument, since otherwise cannot have the same

     * deriving class provide multiple different types of ids

     */

    virtual void NextId(T& aId) = 0;

};

/**

 * TGlxDefaultIdProvider

 * Simple implementation of id provider

 */ 

template <class T>

class TGlxDefaultIdProvider : public MGlxIdProvider<T> {

private:

    TUint iNextIdValue;

public:

    inline TGlxDefaultIdProvider();

    virtual void NextId(T& aId);

};

#include "glxid.inl"

#endif // T_GLXID_H