/*

* Copyright (c) 2007-2008 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:  

*

*/

#ifndef HNXMLMODELCACHE_H_

#define HNXMLMODELCACHE_H_

#include <e32base.h>

#include <e32hashtab.h>

#include <xmlengdom.h>

#include <bautils.h>

/**

 * Suites cache.

 * 

 * This class is designed to support caching xml documents which contain

 * suites definitions.

 * 

 * The cache is directlty used by the xml model provider (CHnXmlModelProvider)

 * and is transparent for other data model's classes.

 * 

 * The cache has a maksimum capacity which is equal to KXmlModelCacheMaxLength.

 * The cache works similarily to a shift register. When the maksimum size of

 * the cache is exceeded then the last element in the cache is removed.

 * On contrary, most often used xml documents are moved to the beggining

 * of the cache.

 * 

 * @since S60 5.0

 * @ingroup group_hnmetadatamodel

 */

NONSHARABLE_CLASS( CHnXmlModelCache ) : public CBase

    {

private:

    /**

     * Default constructor.

     * 

     * @since S60 5.0

     */

    CHnXmlModelCache();

    /**

     * Standard second phase constructor.

     * 

     * @since S60 5.0

     */

    void ConstructL();

    /**

     * Removes a xml document from the cache if the size of the cache

     * is exceeded.

     * 

     * @since S60 5.0

     */

    void RemoveUnused();

    /**

     * Moves the xml document (identified by a given name) to the top of the

     * cache.

     * 

     * @param aSuiteName A name of the xml document to be moved to the top

     *                   of the cache.

     * @since S60 5.0

     */

    void MoveToTopL( const TDesC & aSuiteName );

public:

    /**

     * Two-phase constructor.

     * 

     * @since S60 5.0

     */

    static CHnXmlModelCache* NewLC();

    /**

     * Two-phase constructor.

     * 

     * 

     */

    static CHnXmlModelCache* NewL();

    /**

     * Adds a new xml document into the cache.

     * @param aSuiteName A name of the suite.

     * @param aDocument A xml document to be added to the cache.

     * 

     * @since S60 5.0

     */

    TInt AddL( const TDesC& aSuiteName, RXmlEngDocument& aDocument );

    /**

     * Checks if the xml document is stored in the cache.

     * 

     * @param aSuiteName The name of the suite to be checked.

     * @return ETrue if a suite of a given name is stored in the cache,

     *         otherwise - EFalse.

     *         

     * @since S60 5.0

     */

    TBool IsCachedL( const TDesC& aSuiteName );

    /**

     * Gets a xml document by a given name.

     * 

     * @param aSuiteName The name corresponding to the xml document to be

     *                   retrieved from the cache.

     * @param aDocument The reference to the xml document.

     * 

     * @since S60 5.0

     */

    void GetL( const TDesC& aSuiteName, RXmlEngDocument& aDocument );

    /**

     * Resets the cache - removes all stored xml documents.

     * 

     * @since S60 5.0

     */

    void Reset();

    /**

     * Standard C++ virtual destructor.

     * 

     * @since S60 5.0

     */

    virtual ~CHnXmlModelCache();

private:

    /**

     * The hash map storing pairs: name of the suite, corresponding xml

     * document.

     * 

     * @since S60 5.0

     */

    RHashMap< HBufC*, RXmlEngDocument > iDocuments;

    /**

     * An auxilliary array storing the order of the xml document

     * in the cache.

     * 

     * @since S60 5.0

     */

    RPointerArray< HBufC > iOrder;

    };

#endif /*HNXMLMODELCACHE_H_*/