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1   /*
2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/ext/EvaluateFunction.java,v 1.10 2006/02/05 21:47:42 elharo Exp $
3    * $Revision: 1.10 $
4    * $Date: 2006/02/05 21:47:42 $
5    *
6    * ====================================================================
7    *
8    * Copyright 2000-2002 bob mcwhirter & James Strachan.
9    * All rights reserved.
10   *
11   * Redistribution and use in source and binary forms, with or without
12   * modification, are permitted provided that the following conditions are
13   * met:
14   * 
15   *   * Redistributions of source code must retain the above copyright
16   *     notice, this list of conditions and the following disclaimer.
17   * 
18   *   * Redistributions in binary form must reproduce the above copyright
19   *     notice, this list of conditions and the following disclaimer in the
20   *     documentation and/or other materials provided with the distribution.
21   * 
22   *   * Neither the name of the Jaxen Project nor the names of its
23   *     contributors may be used to endorse or promote products derived 
24   *     from this software without specific prior written permission.
25   * 
26   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
27   * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28   * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
29   * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
30   * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
31   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
32   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
33   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
34   * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
35   * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
36   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37   *
38   * ====================================================================
39   * This software consists of voluntary contributions made by many 
40   * individuals on behalf of the Jaxen Project and was originally 
41   * created by bob mcwhirter <bob@werken.com> and 
42   * James Strachan <jstrachan@apache.org>.  For more information on the 
43   * Jaxen Project, please see <http://www.jaxen.org/>.
44   * 
45   * $Id: EvaluateFunction.java,v 1.10 2006/02/05 21:47:42 elharo Exp $
46   */
47  
48  package org.jaxen.function.ext;
49  
50  import java.util.Collections;
51  import java.util.List;
52  
53  import org.jaxen.Context;
54  import org.jaxen.ContextSupport;
55  import org.jaxen.Function;
56  import org.jaxen.FunctionCallException;
57  import org.jaxen.Navigator;
58  import org.jaxen.XPath;
59  import org.jaxen.function.StringFunction;
60  
61  /***
62   * <code><i>node-set</i> evaluate(<i>string</i>)</code> 
63   *  
64   * @author Erwin Bolwidt (ejb @ klomp.org)
65   */
66  public class EvaluateFunction implements Function
67  {
68      public Object call( Context context, List args )
69          throws FunctionCallException
70      {
71          if ( args.size() == 1 ) {
72              return evaluate( context, args.get(0));
73          }
74  
75          throw new FunctionCallException( "evaluate() requires one argument" );
76      }
77  
78      public static List evaluate (Context context, Object arg)
79          throws FunctionCallException
80      {
81          List contextNodes = context.getNodeSet();
82          
83          if (contextNodes.size() == 0)
84              return Collections.EMPTY_LIST;
85        
86          Navigator nav = context.getNavigator();
87  
88          String xpathString;
89          if ( arg instanceof String )
90              xpathString = (String)arg;
91          else
92              xpathString = StringFunction.evaluate(arg, nav);
93  
94          try {
95              XPath xpath = nav.parseXPath(xpathString);
96              ContextSupport support = context.getContextSupport();
97              xpath.setVariableContext( support.getVariableContext() );
98              xpath.setFunctionContext( support.getFunctionContext() );
99              xpath.setNamespaceContext( support.getNamespaceContext() );
100             return xpath.selectNodes( context.duplicate() );
101         }
102         catch ( org.jaxen.saxpath.SAXPathException e ) {
103             throw new FunctionCallException(e.toString());
104         }
105     }
106 }
107