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1   /*
2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/ext/EvaluateFunction.java,v 1.8 2005/01/26 11:55:40 elharo Exp $
3    * $Revision: 1.8 $
4    * $Date: 2005/01/26 11:55:40 $
5    *
6    * ====================================================================
7    *
8    * Copyright (C) 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
13   * are met:
14   * 
15   * 1. Redistributions of source code must retain the above copyright
16   *    notice, this list of conditions, and the following disclaimer.
17   *
18   * 2. Redistributions in binary form must reproduce the above copyright
19   *    notice, this list of conditions, and the disclaimer that follows 
20   *    these conditions in the documentation and/or other materials 
21   *    provided with the distribution.
22   *
23   * 3. The name "Jaxen" must not be used to endorse or promote products
24   *    derived from this software without prior written permission.  For
25   *    written permission, please contact license@jaxen.org.
26   * 
27   * 4. Products derived from this software may not be called "Jaxen", nor
28   *    may "Jaxen" appear in their name, without prior written permission
29   *    from the Jaxen Project Management (pm@jaxen.org).
30   * 
31   * In addition, we request (but do not require) that you include in the 
32   * end-user documentation provided with the redistribution and/or in the 
33   * software itself an acknowledgement equivalent to the following:
34   *     "This product includes software developed by the
35   *      Jaxen Project (http://www.jaxen.org/)."
36   * Alternatively, the acknowledgment may be graphical using the logos 
37   * available at http://www.jaxen.org/
38   *
39   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
40   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
41   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
42   * DISCLAIMED.  IN NO EVENT SHALL THE Jaxen AUTHORS OR THE PROJECT
43   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
44   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
45   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
46   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
47   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
48   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
49   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
50   * SUCH DAMAGE.
51   *
52   * ====================================================================
53   * This software consists of voluntary contributions made by many 
54   * individuals on behalf of the Jaxen Project and was originally 
55   * created by bob mcwhirter <bob@werken.com> and 
56   * James Strachan <jstrachan@apache.org>.  For more information on the 
57   * Jaxen Project, please see <http://www.jaxen.org/>.
58   * 
59   * $Id: EvaluateFunction.java,v 1.8 2005/01/26 11:55:40 elharo Exp $
60   */
61  
62  package org.jaxen.function.ext;
63  
64  import java.util.Collections;
65  import java.util.List;
66  
67  import org.jaxen.Context;
68  import org.jaxen.ContextSupport;
69  import org.jaxen.Function;
70  import org.jaxen.FunctionCallException;
71  import org.jaxen.Navigator;
72  import org.jaxen.XPath;
73  import org.jaxen.function.StringFunction;
74  
75  /***
76   * <code><i>node-set</i> evaluate(<i>string</i>)</code> 
77   *  
78   * @author Erwin Bolwidt (ejb @ klomp.org)
79   */
80  public class EvaluateFunction implements Function
81  {
82      public Object call( Context context, List args )
83          throws FunctionCallException
84      {
85          if ( args.size() == 1 ) {
86              return evaluate( context, args.get(0));
87          }
88  
89          throw new FunctionCallException( "evaluate() requires one argument" );
90      }
91  
92      public static List evaluate (Context context, Object arg)
93          throws FunctionCallException
94      {
95          List contextNodes = context.getNodeSet();
96          
97          if (contextNodes.size() == 0)
98              return Collections.EMPTY_LIST;
99        
100         Navigator nav = context.getNavigator();
101 
102         String xpathString;
103         if ( arg instanceof String )
104             xpathString = (String)arg;
105         else
106             xpathString = StringFunction.evaluate(arg, nav);
107 
108         try {
109             XPath xpath = nav.parseXPath(xpathString);
110             ContextSupport support = context.getContextSupport();
111             xpath.setVariableContext( support.getVariableContext() );
112             xpath.setFunctionContext( support.getFunctionContext() );
113             xpath.setNamespaceContext( support.getNamespaceContext() );
114             return xpath.selectNodes( context.duplicate() );
115         }
116         catch ( org.jaxen.saxpath.SAXPathException e ) {
117             throw new FunctionCallException(e.toString());
118         }
119     }
120 }
121