// Copyright (c) 2005-2009 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:

// XPath evaluator declaration

//

/**

 @file

 @publishedAll

 @released

*/

#ifndef XMLENGXPATHEVALUATOR_H

#define XMLENGXPATHEVALUATOR_H

#include <xml/dom/xmlengxpathexpression.h>

#include <xml/dom/xmlengxformsinstancemap.h>

#include <xml/dom/xmlengnamespaceresolver.h>

class MXmlEngXPathExtensionFunction;

class MXmlEngNamespaceResolver;

/**

Evaluates XPath expressions on a DOM tree.

See the XPath specfication here:

http://www.w3.org/TR/2004/NOTE-DOM-Level-3-XPath-20040226/xpath.html

*/

class TXmlEngXPathEvaluator

{

public:

    /** Default constructor */

    IMPORT_C TXmlEngXPathEvaluator();

	// XPath 1.0 methods

    /**

    Precompiles and stores an XPath expression, which is returned to caller.

	Information on how to write XPath expressions can be found here:

	@see http://en.wikipedia.org/wiki/XPath

    @param aExpression The expression to create

    @param aResolver Not supported in current API.  Reserved for future use.

    @return The compiled XPath expression.

	@leave KXmlEngErrXPathSyntax Error compiling expression

	@leave KErrNoMemory Memory allocation error

	@leave - Otherwise, any of the system wide errors.

    */

    IMPORT_C RXmlEngXPathExpression CreateExpressionL(const TDesC8& aExpression,

                                   const MXmlEngNamespaceResolver* aResolver = NULL);

    /**

    Evaluates the XPath expression given as a parameter and returns the result.

    @param aExpression The expression to evaluate

    @param aContextNode The node relative to which the expression is evaluated. 

    @param aResolver Not supported in current API. Reserved for future use.

    @return The result of the evaluation.

    @leave KXmlEngErrXPathResult Error evaluating expression

	@leave KXmlEngErrXPathSyntax Error compiling expression

	@leave KErrNoMemory Memory allocation error

	@leave - Otherwise, any of the system wide errors.

    */

    IMPORT_C RXmlEngXPathResult EvaluateL(const TDesC8& aExpression,

                                   const TXmlEngNode aContextNode,

                                   const MXmlEngNamespaceResolver* aResolver = NULL);

	// Extensions to XPath 1.0

	/**

	Does the same thing as EvaluateL(), but also calculates the dependency list

	of the expression.

    @param aExpression The expression to evaluate

    @param aContextNode The node relative to which the expression is evaluated. 

    @param aResolver Not supported in current API. Reserved for future use.

    @param aDependents After the method has returned, contains set of nodes that 

    the expression is dependent on.

    @return The result of evaluation

	@leave KXmlEngErrXPathResult Error evaluating expression

	@leave KXmlEngErrXPathSyntax Error compiling expression

	@leave KErrNoMemory Memory allocation error

	@leave - Otherwise, any of the system wide errors.

    */

    IMPORT_C RXmlEngXPathResult EvaluateWithDependenciesL(const TDesC8& aExpression,

                                   const TXmlEngNode aContextNode,

                                   const MXmlEngNamespaceResolver* aResolver,

                                   RXmlEngNodeSet& aDependents);

    /**

    Registers the instance map to be used when evaluating form expressions. The map 

    contains DOM Documents and their names. For example, when evaluating the expression 

    "instance('a')" the evaluator looks up a document that has the name "a" from the map. 

    @param aInstanceTrees The instance map, ownership is not transferred.

    */

    IMPORT_C void SetInstanceMap(CXmlEngXFormsInstanceMap* aInstanceTrees);

    /**

    Returns the registered instance map.  Ownership is not transferred.

    @return A pointer to the instance map or NULL if not registered.

    */

    IMPORT_C CXmlEngXFormsInstanceMap* InstanceMap();

private:

    CXmlEngXFormsInstanceMap* iInstanceTrees;

};

#endif /* XMLENGXPATHEVALUATOR_H */