XSLTEngine


1   /*
2    * The Apache Software License, Version 1.1
3    *
4    * Copyright (c) 2002 The Apache Software Foundation.  All rights
5    * reserved.
6    *
7    * Redistribution and use in source and binary forms, with or without
8    * modification, are permitted provided that the following conditions
9    * are met:
10   *
11   * 1. Redistributions of source code must retain the above copyright
12   *    notice, this list of conditions and the following disclaimer.
13   *
14   * 2. Redistributions in binary form must reproduce the above copyright
15   *    notice, this list of conditions and the following disclaimer in
16   *    the documentation and/or other materials provided with the
17   *    distribution.
18   *
19   * 3. The end-user documentation included with the redistribution, if
20   *    any, must include the following acknowlegement:
21   *       "This product includes software developed by the
22   *        Apache Software Foundation (http://www.apache.org/)."
23   *    Alternately, this acknowlegement may appear in the software itself,
24   *    if and wherever such third-party acknowlegements normally appear.
25   *
26   * 4. The names "Apache BSF", "Apache", and "Apache Software Foundation"
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28   *    this software without prior written permission. For written
29   *    permission, please contact apache@apache.org.
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31   * 5. Products derived from this software may not be called "Apache"
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35   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
36   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
37   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
38   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
39   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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41   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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43   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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47   * ====================================================================
48   *
49   * This software consists of voluntary contributions made by many individuals
50   * on behalf of the Apache Software Foundation and was originally created by
51   * Sanjiva Weerawarana and others at International Business Machines
52   * Corporation. For more information on the Apache Software Foundation,
53   * please see <http://www.apache.org/>.
54   */
55  
56  package org.apache.bsf.engines.xslt;
57  
58  import java.util.*;
59  import java.io.*;
60  import java.net.URL  ;
61  
62  import javax.xml.transform.Transformer  ;
63  import javax.xml.transform.TransformerFactory  ;
64  import javax.xml.transform.dom.DOMResult  ;
65  import javax.xml.transform.dom.DOMSource  ;
66  import javax.xml.transform.stream.StreamSource  ;
67  
68  import org.w3c.dom.*;
69  
70  import org.apache.xpath.objects.XObject;
71  
72  import org.apache.bsf.*;
73  import org.apache.bsf.util.BSFEngineImpl;
74  import org.apache.bsf.util.BSFFunctions;
75  import org.apache.bsf.debug.util.DebugLog;
76  
77  /**
78   * Xerces XSLT interface to BSF. Requires Xalan and Xerces from Apache.
79   * 
80   * This integration uses the BSF registry to pass in any src document
81   * and stylesheet base URI that the user may wish to set. 
82   *
83   * @author   Sanjiva Weerawarana
84   * @author   Sam Ruby
85   *
86   * Re-implemented for the Xalan 2 codebase
87   * 
88   * @author   Victor J. Orlikowski
89   */
90  public class XSLTEngine extends BSFEngineImpl {
91      TransformerFactory   tFactory;
92      Transformer   transformer;
93  
94      /**
95       * call the named method of the given object.
96       */
97      public Object   call (Object   object, String   method, Object  [] args) 
98          throws BSFException {
99      throw new BSFException (BSFException.REASON_UNSUPPORTED_FEATURE,
100                                 "BSF:XSLTEngine can't call methods");
101     }
102 
103     /**
104      * Declare a bean by setting it as a parameter
105      */
106     public void declareBean (BSFDeclaredBean bean) throws BSFException {
107         transformer.setParameter (bean.name, new XObject (bean.bean));
108     }
109 
110     /**
111      * Evaluate an expression. In this case, an expression is assumed
112      * to be a stylesheet of the template style (see the XSLT spec).
113      */
114     public Object   eval (String   source, int lineNo, int columnNo, 
115                         Object   oscript) throws BSFException {
116     // get the style base URI (the place from where Xerces XSLT will
117     // look for imported/included files and referenced docs): if a
118     // bean named "xslt:styleBaseURI" is registered, then cvt it
119     // to a string and use that. Otherwise use ".", which means the
120     // base is the directory where the process is running from
121     Object   sbObj = mgr.lookupBean ("xslt:styleBaseURI");
122     String   styleBaseURI = (sbObj == null) ? "." : sbObj.toString ();
123 
124     // Locate the stylesheet.
125     StreamSource   styleSource;
126 
127         styleSource = 
128             new StreamSource  (new StringReader(oscript.toString ()));
129         styleSource.setSystemId(styleBaseURI);
130 
131         try {
132             transformer = tFactory.newTransformer(styleSource);
133         } catch (Exception   e) {
134             e.printStackTrace (DebugLog.getDebugStream());
135             throw new BSFException (BSFException.REASON_EXECUTION_ERROR,
136                                     "Exception from Xerces XSLT: " + e, e);
137         }
138 
139     // get the src to work on: if a bean named "xslt:src" is registered
140     // and its a Node, then use it as the source. If its not a Node, then
141     // if its a URL parse it, if not treat it as a file and make a URL and
142     // parse it and go. If no xslt:src is found, use an empty document
143     // (stylesheet is treated as a literal result element stylesheet)
144     Object   srcObj = mgr.lookupBean ("xslt:src");
145     Object   xis = null;
146     if (srcObj != null) {
147             if (srcObj instanceof Node) {
148         xis = new DOMSource  ((Node)srcObj);
149             } else {
150         try {
151                     String   mesg = "as anything";
152                     if (srcObj instanceof Reader) {
153             xis = new StreamSource   ((Reader) srcObj);
154             mesg = "as a Reader";
155                     } else if (srcObj instanceof File) {
156                         xis = new StreamSource   ((File) srcObj);
157                         mesg = "as a file";
158                     } else {
159                         String   srcObjstr=srcObj.toString();
160                         xis = new StreamSource   (new StringReader(srcObjstr));
161                         if (srcObj instanceof URL  ) {
162                             mesg = "as a URL";
163                         } else {
164                             ((StreamSource  ) xis).setPublicId (srcObjstr);
165                             mesg = "as an XML string";
166                         }
167                     }
168 
169                     if (xis == null) {
170             throw new Exception   ("Unable to get input from '" +
171                                              srcObj + "' " + mesg);
172                     }
173         } catch (Exception   e) {
174                     throw new BSFException (BSFException.REASON_EXECUTION_ERROR,
175                                             "BSF:XSLTEngine: unable to get " +
176                                             "input from '" + srcObj + "' as XML", e);
177         }
178             }
179     } else {
180             // create an empty document - real src must come into the 
181             // stylesheet using "doc(...)" [see XSLT spec] or the stylesheet
182             // must be of literal result element type
183             xis = new StreamSource  ();
184     }
185     
186     // set all declared beans as parameters.
187     for (int i = 0; i < declaredBeans.size (); i++) {
188             BSFDeclaredBean b = (BSFDeclaredBean) declaredBeans.elementAt (i);
189             transformer.setParameter (b.name, new XObject (b.bean));
190     }
191 
192     // declare a "bsf" parameter which is the BSF handle so that 
193     // the script can do BSF stuff if it wants to
194     transformer.setParameter ("bsf", 
195                                   new XObject (new BSFFunctions (mgr, this)));
196 
197     // do it
198     try {
199             DOMResult   result = new DOMResult  ();
200             transformer.transform ((StreamSource  ) xis, result);
201             return new XSLTResultNode (result.getNode());
202     } catch (Exception   e) {
203             throw new BSFException (BSFException.REASON_EXECUTION_ERROR,
204                                     "exception while eval'ing XSLT script" + e, e);
205     }
206     }
207 
208     /**
209      * Initialize the engine.
210      */
211     public void initialize (BSFManager mgr, String   lang,
212                             Vector declaredBeans) throws BSFException {
213     super.initialize (mgr, lang, declaredBeans);
214 
215         tFactory = TransformerFactory.newInstance();
216     }
217 
218     /**
219      * Undeclare a bean by setting he parameter represeting it to null
220      */
221     public void undeclareBean (BSFDeclaredBean bean) throws BSFException {
222         // Cannot clear only one parameter in Xalan 2, so we set it to null
223         if ((transformer.getParameter (bean.name)) != null) {
224             transformer.setParameter (bean.name, null);
225         }
226     }
227 }
228
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