1 // Copyright (c) 2005-2009 Nokia Corporation and/or its subsidiary(-ies).

     2 // All rights reserved.

     3 // This component and the accompanying materials are made available

     4 // under the terms of "Eclipse Public License v1.0"

     5 // which accompanies this distribution, and is available

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

     7 //

     8 // Initial Contributors:

     9 // Nokia Corporation - initial contribution.

    10 //

    11 // Contributors:

    12 //

    13 // Description:

    14 // Extension function interface

    15 //

    16 

    17 

    18 

    19 /**

    20  @file

    21  @publishedAll

    22  @released

    23 */

    24 #ifndef XMLENGXPATHFUNCTION_H

    25 #define XMLENGXPATHFUNCTION_H

    26 

    27 #include <xml/dom/xmlengxpathresult.h>

    28 

    29 class MXmlEngXPathEvaluationContext;

    30 

    31 /**

    32 Provides an interface for an object to participate in the evaluation of XPath

    33 expression via a XPath function call.

    34 

    35 Objects that implement the MXmlEngXPathExtensionFunction interface can be

    36 registered in a XmlEngXPathConfiguration object for global action (across

    37 all evaluations globally). 

    38 

    39 @see XmlEngXPathConfiguration::AddExtensionFunctionL()

    40 

    41 When the extension function is no longer required, it must be deregistered

    42 by calling XmlEngXPathConfiguration::RemoveExtensionFunction().

    43 */ 

    44 class MXmlEngXPathExtensionFunction

    45     {

    46 public:

    47     /** Evaluation status */

    48     enum TXmlEngEvaluationStatus

    49         {

    50 		/** Evaluation was accomplished successfully */

    51         ESucceeded,

    52 		/** An exceptional condition occurs */

    53         EError,

    54 		/** Type of argument does not match function specification */

    55         EInvalidArgumentType,

    56 		/** Number of arguments do not match function specification */

    57         EInvalidArgumentNumber

    58         };

    59         

    60 public:

    61     /** 

    62     Gets the minimum number of arguments the function can take.

    63     @return Minimum number of arguments

    64     */

    65     virtual TInt MinArity() {return 0;}

    66 

    67     /** 

    68     Gets the maximum number of arguments the function can take.

    69     

    70 	@return The maximum number of arguments or -1 if unbounded

    71     */

    72     virtual TInt MaxArity() {return MinArity();}

    73 

    74     /**

    75 	Called to evaluate the extension function.

    76 

    77 	This function is called only if simple arity constraints (min/max number of

    78 	arguments) are satisfied. The implementation of this function may need to

    79 	check further that the types of arguments and their positions in the

    80 	function call match function-specific requirements.

    81     

    82 	@param aEvalCtxt Evaluation context, which contains data about arguments

    83 	and provides a number of methods for setting the result of the extension

    84 	function.

    85 

    86     @return ESucceeded if evaluation success, otherwise one of the errors 

    87 	defined in TXmlEngEvaluationStatus.

    88     */

    89     virtual TXmlEngEvaluationStatus Evaluate(MXmlEngXPathEvaluationContext* aEvalCtxt) = 0; 

    90     };

    91 

    92 #endif /* XMLENGXPATHFUNCTION_H */

    93