content: /*
   * $Header$
   * $Revision$
   * $Date$
   *
   * ====================================================================
   *
   * 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/>.
   * 
   * $Id$
   */
  
  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());
          }
      }
  }
  
  