/*

* Copyright (c) 2007 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:  Class declaration for MStateMachineObserver

*

*/

#ifndef DIAGENGINESTATEMACHINEOBSERVER_H

#define DIAGENGINESTATEMACHINEOBSERVER_H

// system include

// user include

#include "diagenginestates.h"   // DiagFwInternal::TState

#include "diagengineevents.h"   // DiagFwInternal::TEvent

namespace DiagFwInternal

    {

// forward declaration

class CEventBasic;

/**

 *  Diagnostics Framework Engine State Machine Observer

 *

 *  This interface is called by CDiagEngineStateMachine to notify

 *  its client of state changes and events.

 *

 *  @since S60 v5.0

 */

class MStateMachineObserver

    {

public:

    /**

    * Notify state machine client that state machine has entered a new state.

    *

    * @param aPreviousState     Previous state.

    * @param aCurrentState      Current state. (new state.)

    * @param aEventPreview  Event that caused state change. Note that

    *   this is just a preview.  HandleEventL() will be called with the same

    *   event later on.

    */

    virtual void HandleStateChangedL( TState aPreviousState, 

                                      TState aCurrentState,

                                      const CEventBasic& aEventPreview ) = 0;

    /**

    * Notify state machine client that a new event is received.

    *

    * @param aEvent        New event.

    */

    virtual void HandleEventL( CEventBasic& aEvent ) = 0;

    /**

    * Notify state machine client that an abnormal error has occured.

    * Client can handle the error and return appropriate error state.

    *

    * @param aCurrentState Current state.

    * @param aError        Error number.

    * @return TState       New state to go to.

    */

    virtual TState HandleError( TState aCurrentState, TInt aError ) = 0;

    };

    } // end of namespace DiagFwInternal

#endif // DIAGENGINESTATEMACHINEOBSERVER_H

// End of File