/*

  * $Header$

  * $Revision: 1128 $

  * $Date: 2006-02-05 13:49:04 -0800 (Sun, 05 Feb 2006) $

  *

  * ====================================================================

  *

  * Copyright 2000-2002 bob mcwhirter & James Strachan.

  * All rights reserved.

  *

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted provided that the following conditions are

  * met:

  * 

  *   * Redistributions of source code must retain the above copyright

  *     notice, this list of conditions and the following disclaimer.

  * 

  *   * Redistributions in binary form must reproduce the above copyright

  *     notice, this list of conditions and the following disclaimer in the

  *     documentation and/or other materials provided with the distribution.

  * 

  *   * Neither the name of the Jaxen Project nor the names of its

  *     contributors may be used to endorse or promote products derived 

  *     from this software without specific prior written permission.

  * 

  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS

  * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED

  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A

  * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER

  * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF

  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING

  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

  *

  * ====================================================================

  * This software consists of voluntary contributions made by many 

  * individuals on behalf of the Jaxen Project and was originally 

  * created by bob mcwhirter <bob@werken.com> and 

  * James Strachan <jstrachan@apache.org>.  For more information on the 

  * Jaxen Project, please see <http://www.jaxen.org/>.

  * 

  * $Id: EvaluateFunction.java 1128 2006-02-05 21:49:04Z elharo $

  */

 package org.jaxen.function.ext;

 import java.util.Collections;

 import java.util.List;

 import org.jaxen.Context;

 import org.jaxen.ContextSupport;

 import org.jaxen.Function;

 import org.jaxen.FunctionCallException;

 import org.jaxen.Navigator;

 import org.jaxen.XPath;

 import org.jaxen.function.StringFunction;

 /**

  * <code><i>node-set</i> evaluate(<i>string</i>)</code> 

  *  

  * @author Erwin Bolwidt (ejb @ klomp.org)

  */

 public class EvaluateFunction implements Function

 {

     public Object call( Context context, List args )

         throws FunctionCallException

     {

         if ( args.size() == 1 ) {

             return evaluate( context, args.get(0));

         }

         throw new FunctionCallException( "evaluate() requires one argument" );

     }

     public static List evaluate (Context context, Object arg)

         throws FunctionCallException

     {

         List contextNodes = context.getNodeSet();

         if (contextNodes.size() == 0)

             return Collections.EMPTY_LIST;

         Navigator nav = context.getNavigator();

         String xpathString;

         if ( arg instanceof String )

             xpathString = (String)arg;

         else

             xpathString = StringFunction.evaluate(arg, nav);

         try {

             XPath xpath = nav.parseXPath(xpathString);

             ContextSupport support = context.getContextSupport();

             xpath.setVariableContext( support.getVariableContext() );

             xpath.setFunctionContext( support.getFunctionContext() );

             xpath.setNamespaceContext( support.getNamespaceContext() );

             return xpath.selectNodes( context.duplicate() );

         }

         catch ( org.jaxen.saxpath.SAXPathException e ) {

             throw new FunctionCallException(e.toString());

         }

     }

 }