// 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 evaluation context declaration

//

/**

 @file

 @internalComponent

 @released

*/

#ifndef XMLENGXPATHEVALCTXT_IMPL_H

#define XMLENGXPATHEVALCTXT_IMPL_H

#include <xml/dom/xmlengxpathevaluationcontext.h>

#include <libxml2_xpathinternals.h>

/**

 * XPath evaluation context

 *

 */

class TXmlEngXPathEvaluationContextImpl: public MXmlEngXPathEvaluationContext

    {

public:

	/**

     * Constructor

	 * 

	 * @param aContext Pointer to XPath parser context

	 * @param aArgCount Number of arguments

	 */

    TXmlEngXPathEvaluationContextImpl(xmlXPathParserContextPtr aContext, TUint aArgCount)

        : iContext(aContext), 

          iArgCount(aArgCount), 

          iCurrentResult(NULL),

          iOOM(EFalse) {}

	/**

     * Get number of arguments provided

     *

     * @return Number of arguments provided

     *

     * @note 

     *    The implementation of extension function should not check

     *    that ArgCount() returns value in the range [ MinArity() ; MaxArity() ]

     *    - the function is called iif the statement holds:<br>

     *      <b>MinArity()</b>  =<  <i>arg.count</i>  =< <b>MaxArity()</b> 

     */

    TUint ArgCount();

	/**

     * Retrieves arguments by index (zero-based)

     *

     * @return N-th argument of the function

     *

     * @note

     *    - Argument index starts at 0

     *    - Returned result should not be freed

     */

    const RXmlEngXPathResult Argument(TUint aIndex);

	/**

     * Get the result written so far.

     * 

     * @return Result evaluated by the function so far.

     *

     * Initially, function result is undefined. It can be changed

     * by SetResult() functions for a boolean, string or number values 

     * or by combined use of InitializeNodeSetResult() and AppendToResult() methods

     */

    const RXmlEngXPathResult Result();

	/**

     * Sets a NODESET type of the result (floating-point number): an empty

     * instance of NodeSet is created.

     *

     * The node set is to be filled up by methods AppendToResult(TXmlEngNode) and AppendToResult(RXmlEngNodeSet)

     * This method replaces any existing prepared result so far 

     * (even an initialized already node set)

     * @see AppendToResult(TXmlEngNode), AppendToResult(RXmlEngNodeSet)

     *

     */ 

    void  InitializeNodeSetResult();     

	/**

     * Appends a node to the node set result.

     * @note InitializeNodeSetResult() should be called prior any call to 

     *       AppendToResult(TXmlEngNode) or AppendToResult(RXmlEngNodeSet)

     *

     * @param aNode Node that should be add

     */ 

    void  AppendToResult(const TXmlEngNode aNode);

    void  AppendToResult(const TXmlEngNamespace aAppendedNsNode, const TXmlEngElement aNsParentNode);

	/**

    * Appends a node set to the node set result. Nodes are merged into resulting node set.

    * @note InitializeNodeSetResult() should be called prior any call to 

    *       AppendToResult(TXmlEngNode) or AppendToResult(RXmlEngNodeSet)

    *

    * @param aNodeSet Nodes that should be add

    */

    void  AppendToResult(const RXmlEngNodeSet aNodeSet);

	/**

     * Sets a NUMBER type of the result (a floating-point number)

     *

     * @param aNumber New number

     */ 

    void  SetResult(TReal aNumber);

	/**

     * Sets a BOOLEAN type of the result 

     *

     * @param aBoolean New value

     */

    void  SetResult(TBool aBoolean);

	/**

     * Sets a STRING type of the result

     *

     * @param aString New string value

     */

    void  SetResultL(const TDesC8& aString);

	/**

     * Gets data specified in RXmlEngXPathExpression::SetExtendedContext(void*) method

     * for the expression currently being evaluated.

     *

     */ 

    void* ExtendedContext();

    /**

     * Allocates memory for function result

     * 

     * @return TRUE is succeeded, FALSE if OOM has happened

     */

    TBool Initialize();

private:

	/** XPath parser */

    xmlXPathParserContextPtr iContext;

	/** Arguments count */

    TUint iArgCount;

	/** XPath object */

    xmlXPathObjectPtr iCurrentResult;    

	/** OOM flag */

    TBool iOOM;

    };

#endif /* XMLENGXPATHEVALCTXT_IMPL_H */