/*

* Copyright (c) 2004-2005 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:  The base class for engines

*

*/

#ifndef __LANDMARKS_ENGINE_BASE_H__

#define __LANDMARKS_ENGINE_BASE_H__

//  INCLUDES

#include <e32base.h>

#include <EPos_Landmarks.h>

class CPosLandmarkDatabase;

class CPosLandmarkSearch;

class CLandmarksLmOpWrapper;

/**

*  Abstract base class for sub engines.

*

*/

class CLandmarksEngineBase : public CActive

    {

    public: // Constructors and destructor

        /**

        * Destructor.

        */

        ~CLandmarksEngineBase();

    public: // New functions

        /**

        * SetPrio updates the @ref iPriority data member.

        *

        * @param aPriority the priority to set

        */

        void SetPrio(CActive::TPriority aPriority);

    protected: // From CActive

        /**

        * RunL should be implemented by sub classes.

        */

        virtual void RunL() = 0;

        /**

        * DoCancel should be implemented by sub classes.

        */

        virtual void DoCancel() = 0;

        /**

        * RunError should be implemented by sub classes in case RunL might 

        * leave.

        */

        virtual TInt RunError(TInt aError) = 0;

    protected: // New functions

        /**

        * C++ constructor.

        * 

        * @param aDb an instance of the default landmark database

        */

        CLandmarksEngineBase(CPosLandmarkDatabase& aDb);

        /**

        * By default Symbian 2nd phase constructor is private.

        */

        void ConstructL();

        /**

        * SetPriorityAndSetActive updates the priority of this active object 

        * if necessary and sets it to active. This method should be used by sub 

        * classes rather than CActive::SetActive()

        */

        void SetPriorityAndSetActive();

    protected: // Data

        //! The default landmark database

        CPosLandmarkDatabase& iDb;

        //! Used for searching the database

        CPosLandmarkSearch* iSearcher;

        //! An active object wrapping a CPosLmOperation object

        CLandmarksLmOpWrapper* iLmOpWrapper;

    private: // Data

        //! Used when setting priority of this active object

        CActive::TPriority iPriority;

    };

#endif // __LANDMARKS_ENGINE_BASE_H__