1 /*

     2 * Copyright (c) 2004-2008 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:  CCFContextOperation class declaration.

    15 *

    16 */

    17 

    18 

    19 

    20 #ifndef C_CFCONTEXTOPERATION_H

    21 #define C_CFCONTEXTOPERATION_H

    22 

    23 // INCLUDES

    24 #include <e32base.h>

    25 #include <cfcontextobject.h>

    26 

    27 #include "cfoperationnode.h"

    28 #include "cfscriptlistener.h"

    29 

    30 // FORWARD DECLARATIONS

    31 

    32 // CLASS DECLARATION

    33 

    34 /**

    35 *  CCFContextOperation class is the base class for all Context Framework script

    36 *  operations that operate on contexts.

    37 *  All instances of this class are leaf nodes in operation tree.

    38 *

    39 *  @lib CFScriptEngine

    40 *  @since Series 60 2.6

    41 */

    42 NONSHARABLE_CLASS( CCFContextOperation ): public CCFOperationNode,

    43     public MCFScriptListener

    44     {

    45 public: // Constructors and destructor

    46 

    47     /**

    48     * Destructor.

    49     */

    50     virtual ~CCFContextOperation();

    51 

    52 public: // Enumerations

    53 

    54     enum TCmpType

    55         {

    56         EInvalidCmpType = -1,

    57         EIntCmp,

    58         EFloatCmp,

    59         EPositionCmp,

    60         ETimeCmp,

    61         EStringCmp

    62         };

    63 

    64 

    65 public: // From MCFScriptListener

    66 

    67     /**

    68     * Performs evaluation based on a context.

    69     * @param aContext is the context for evaluation.

    70     * @param aContextLevelDelay is storage for context level delay required by

    71     *   the evaluation.

    72     * @return ETrue if evaluation was performed and firing actions should be

    73     *   considered based on clause conditions, EFalse otherwise.

    74     */

    75     TBool Evaluate( const CCFContextObject& aContext,

    76             TInt& aContextLevelDelay );

    77 

    78     /**

    79     * Returns a context source this listener is interested in.

    80     * @returns the source of the context.

    81     */

    82     TPtrC Source() const;

    83 

    84     /**

    85     * Returns a context type this listener is interested in.

    86     * @returns the type of the context.

    87     */

    88     TPtrC Type() const;

    89 

    90     /**

    91     * Tests if this listener requires notification of all contexts.

    92     * @returns ETrue if this listener is interested in all contexts,

    93     *   EFalse otherwise.

    94     */

    95     TBool IsAllRequired() const;

    96 

    97 protected:

    98 

    99     /**

   100     * C++ default constructor.

   101     */

   102     CCFContextOperation( MCFOperationServices& aServices,

   103             CCFOperationNode* aParent,

   104             HBufC* aType,

   105             HBufC* aSource );

   106 

   107 protected: // New functions

   108 

   109     /**

   110     * All concrete classes must implement this method.

   111     * @param aContext is context that has changed.

   112     * @return the result of the comparison.

   113     */

   114     virtual TBool IsTrueL( const CCFContextObject& aContext ) = 0;

   115 

   116     /**

   117     * Updates the previous value the operation was evaluated with.

   118     * @param aNewValue is the new previous value.

   119     * @return KErrNone when update was successful, KErrNoMemory if update failed

   120     *   due to low memory.

   121     */

   122     TInt UpdatePreviousValue( const TDesC& aNewValue );

   123 

   124     /**

   125     * Gets the previous value the operation was evaluated with.

   126     * @return the previous value the operation was evaluated with.

   127     */

   128     const TDesC& PreviousValue();

   129 

   130 protected: // From CCFOperationNode

   131 

   132     /**

   133     * Activates this node by subscribing to a context.

   134     * @return None.

   135     */

   136     void ActivateL();

   137 

   138     /**

   139     * Deactivates this node by removing context subscription.

   140     * @return None.

   141     */

   142     void Deactivate();

   143 

   144     /**

   145     * Asks this node to check its security (via services interface). For

   146     * example, the security of contexts to be subscribed.

   147     * @return KErrNone if security check passed, otherwise any of the system

   148     *   wide error codes.

   149     */

   150     TInt CheckSecurity();

   151 

   152 private: // From CCFOperationNode

   153 

   154     /**

   155     * Called by child node, to ask the parent to re-evaluate its value,

   156     * since the child's value has changed.

   157     */

   158     void Evaluate();

   159 

   160 protected: // Data

   161 

   162     /**

   163     * Context level delay for firing actions after evaluation

   164     * (defined by contextRef).

   165     */

   166     TInt iContextLevelDelay;

   167 

   168 private: // Data

   169 

   170     /**

   171     * Context source and type as defined by contextRef for the operation.

   172     */

   173     HBufC* iSource;

   174     HBufC* iType;

   175 

   176     /** Previous context value. */

   177     HBufC* iPreviousValue;

   178     };

   179 

   180 #endif // C_CFCONTEXTOPERATION_H