1 /*

     2 * Copyright (c) 2007-2008 Nokia Corporation and/or its subsidiary(-ies).

     3 * All rights reserved.

     4 * This component and the accompanying materials are made available

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

     6 * which accompanies this distribution, and is available

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

     8 *

     9 * Initial Contributors:

    10 * Nokia Corporation - initial contribution.

    11 *

    12 * Contributors:

    13 *

    14 * Description:  

    15 *

    16 */

    17 

    18 

    19 #ifndef HNXMLMODELCACHE_H_

    20 #define HNXMLMODELCACHE_H_

    21 

    22 #include <e32base.h>

    23 #include <e32hashtab.h>

    24 #include <xmlengdom.h>

    25 #include <bautils.h>

    26 

    27 

    28 /**

    29  * Suites cache.

    30  * 

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

    32  * suites definitions.

    33  * 

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

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

    36  * 

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

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

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

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

    41  * of the cache.

    42  * 

    43  * @since S60 5.0

    44  * @ingroup group_hnmetadatamodel

    45  */

    46 NONSHARABLE_CLASS( CHnXmlModelCache ) : public CBase

    47     {

    48 

    49 private:

    50     

    51     /**

    52      * Default constructor.

    53      * 

    54      * @since S60 5.0

    55      */

    56     CHnXmlModelCache();

    57     

    58     /**

    59      * Standard second phase constructor.

    60      * 

    61      * @since S60 5.0

    62      */

    63     void ConstructL();

    64     

    65     /**

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

    67      * is exceeded.

    68      * 

    69      * @since S60 5.0

    70      */

    71     void RemoveUnused();

    72     

    73     /**

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

    75      * cache.

    76      * 

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

    78      *                   of the cache.

    79      * @since S60 5.0

    80      */

    81     void MoveToTopL( const TDesC & aSuiteName );

    82 

    83 public:

    84     

    85     /**

    86      * Two-phase constructor.

    87      * 

    88      * @since S60 5.0

    89      */

    90     static CHnXmlModelCache* NewLC();

    91     

    92     /**

    93      * Two-phase constructor.

    94      * 

    95      * 

    96      */

    97     static CHnXmlModelCache* NewL();

    98     

    99     /**

   100      * Adds a new xml document into the cache.

   101      * @param aSuiteName A name of the suite.

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

   103      * 

   104      * @since S60 5.0

   105      */

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

   107     

   108     /**

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

   110      * 

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

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

   113      *         otherwise - EFalse.

   114      *         

   115      * @since S60 5.0

   116      */

   117     TBool IsCachedL( const TDesC& aSuiteName );

   118     

   119     /**

   120      * Gets a xml document by a given name.

   121      * 

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

   123      *                   retrieved from the cache.

   124      * @param aDocument The reference to the xml document.

   125      * 

   126      * @since S60 5.0

   127      */

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

   129     

   130     /**

   131      * Resets the cache - removes all stored xml documents.

   132      * 

   133      * @since S60 5.0

   134      */

   135     void Reset();

   136     

   137     /**

   138      * Standard C++ virtual destructor.

   139      * 

   140      * @since S60 5.0

   141      */

   142     virtual ~CHnXmlModelCache();

   143 

   144 private:

   145     

   146     /**

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

   148      * document.

   149      * 

   150      * @since S60 5.0

   151      */

   152     RHashMap< HBufC*, RXmlEngDocument > iDocuments;

   153     

   154     /**

   155      * An auxilliary array storing the order of the xml document

   156      * in the cache.

   157      * 

   158      * @since S60 5.0

   159      */

   160     RPointerArray< HBufC > iOrder;

   161     

   162     };

   163 

   164 #endif /*HNXMLMODELCACHE_H_*/