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1   /*
2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/DefaultNavigator.java,v 1.16 2005/05/30 12:48:38 elharo Exp $
3    * $Revision: 1.16 $
4    * $Date: 2005/05/30 12:48:38 $
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: DefaultNavigator.java,v 1.16 2005/05/30 12:48:38 elharo Exp $
60   */
61  
62  
63  
64  package org.jaxen;
65  
66  import java.util.Iterator;
67  
68  import org.jaxen.pattern.Pattern;
69  import org.jaxen.util.AncestorAxisIterator;
70  import org.jaxen.util.AncestorOrSelfAxisIterator;
71  import org.jaxen.util.DescendantAxisIterator;
72  import org.jaxen.util.DescendantOrSelfAxisIterator;
73  import org.jaxen.util.FollowingAxisIterator;
74  import org.jaxen.util.FollowingSiblingAxisIterator;
75  import org.jaxen.util.PrecedingAxisIterator;
76  import org.jaxen.util.PrecedingSiblingAxisIterator;
77  import org.jaxen.util.SelfAxisIterator;
78  
79  /*** Default implementation of {@link Navigator}.
80   *
81   *  <p>
82   *  This implementation is an abstract class, since
83   *  some required operations cannot be implemented without
84   *  additional knowledge of the object model.
85   *  </p>
86   *
87   *  <p>
88   *  When possible, default method implementations build
89   *  upon each other, to reduce the number of methods required
90   *  to be implemented for each object model.  All methods,
91   *  of course, may be overridden, to provide more-efficient
92   *  implementations.
93   *  </p>
94   *
95   *  @author bob mcwhirter (bob@werken.com)
96   *  @author Erwin Bolwidt (ejb@klomp.org)
97   */
98  public abstract class DefaultNavigator implements Navigator
99  {
100 
101     /*** Throws <code>UnsupportedAxisException</code>
102      * 
103      * @param contextNode
104      * @return never returns
105      * @throws UnsupportedAxisException always
106      */
107     public Iterator getChildAxisIterator(Object contextNode) throws UnsupportedAxisException
108     {
109         throw new UnsupportedAxisException("child");
110     }
111 
112     /* (non-Javadoc)
113      * @see org.jaxen.Navigator#getDescendantAxisIterator(java.lang.Object)
114      */
115     public Iterator getDescendantAxisIterator(Object contextNode) throws UnsupportedAxisException
116     {
117         return new DescendantAxisIterator( contextNode,
118                                            this );
119     }
120 
121     /*** Throws <code>UnsupportedAxisException</code>
122      * 
123      * @param  contextNode
124      * @return never returns
125      * @throws UnsupportedAxisException
126      */
127     public Iterator getParentAxisIterator(Object contextNode) throws UnsupportedAxisException
128     {
129         throw new UnsupportedAxisException("parent");
130     }
131 
132     public Iterator getAncestorAxisIterator(Object contextNode) throws UnsupportedAxisException
133     {
134         return new AncestorAxisIterator( contextNode,
135                                          this );
136     }
137 
138 
139     public Iterator getFollowingSiblingAxisIterator(Object contextNode) throws UnsupportedAxisException
140     {
141         return new FollowingSiblingAxisIterator( contextNode,
142                                                  this );
143     }
144 
145 
146     public Iterator getPrecedingSiblingAxisIterator(Object contextNode) throws UnsupportedAxisException
147     {
148         return new PrecedingSiblingAxisIterator( contextNode,
149                                                  this );
150     }
151 
152     public Iterator getFollowingAxisIterator(Object contextNode) throws UnsupportedAxisException
153     {
154         return new FollowingAxisIterator( contextNode,
155                                           this );
156 
157         // throw new UnsupportedAxisException("following");
158     }
159 
160 
161     public Iterator getPrecedingAxisIterator(Object contextNode) throws UnsupportedAxisException
162     {
163         return new PrecedingAxisIterator( contextNode,
164                                          this );
165 
166         // throw new UnsupportedAxisException("preceding");
167     }
168 
169     /*** Throws <code>UnsupportedAxisException</code>. Subclasses that 
170      * support the attribute axis must override this method.
171      * 
172      * @param contextNode
173      * @return never returns
174      * @throws UnsupportedAxisException
175      */
176     public Iterator getAttributeAxisIterator(Object contextNode) throws UnsupportedAxisException
177     {
178         throw new UnsupportedAxisException("attribute");
179     }
180 
181     /*** Throws <code>UnsupportedAxisException</code>. Subclasses that 
182      * support the namespace axis must override this method.
183      * 
184      * @param contextNode
185      * @return never returns
186      * @throws UnsupportedAxisException
187      */
188     public Iterator getNamespaceAxisIterator(Object contextNode) throws UnsupportedAxisException
189     {
190         throw new UnsupportedAxisException("namespace");
191     }
192 
193     public Iterator getSelfAxisIterator(Object contextNode) throws UnsupportedAxisException
194     {
195         return new SelfAxisIterator( contextNode );
196     }
197 
198     public Iterator getDescendantOrSelfAxisIterator(Object contextNode) throws UnsupportedAxisException
199     {
200         return new DescendantOrSelfAxisIterator( contextNode,
201                                                  this );
202     }
203 
204     public Iterator getAncestorOrSelfAxisIterator(Object contextNode) throws UnsupportedAxisException
205     {
206         return new AncestorOrSelfAxisIterator( contextNode,
207                                                this );
208     }
209 
210     public Object getDocumentNode(Object contextNode)
211     {
212         return null;
213     }
214     
215     public String translateNamespacePrefixToUri(String prefix, Object element)
216     {
217         return null;
218     }
219 
220     public String getProcessingInstructionTarget(Object obj)
221     {
222         return null;
223     }
224 
225     public String getProcessingInstructionData(Object obj)
226     {
227         return null;
228     }
229 
230     public short getNodeType(Object node)
231     {
232         if ( isElement(node) ) 
233         {
234             return Pattern.ELEMENT_NODE;
235         }
236         else if ( isAttribute(node) ) 
237         {
238             return Pattern.ATTRIBUTE_NODE;
239         }
240         else if ( isText(node) ) 
241         {
242             return Pattern.TEXT_NODE;
243         }
244         else if ( isComment(node) ) 
245         {
246             return Pattern.COMMENT_NODE;
247         }
248         else if ( isDocument(node) ) 
249         {
250             return Pattern.DOCUMENT_NODE;
251         }
252         else if ( isProcessingInstruction(node) ) 
253         {
254             return Pattern.PROCESSING_INSTRUCTION_NODE;
255         }
256         else if ( isNamespace(node) ) 
257         {
258             return Pattern.NAMESPACE_NODE;
259         }
260         else {
261             return Pattern.UNKNOWN_NODE;
262         }
263     }
264     
265     /***
266      *  Default implementation that cannot find parent. Subclasses for
267      *  models with parent should override this method.
268      *
269      * @param contextNode   the node whose parent to return
270      * @return null
271      * @throws UnsupportedAxisException if the parent axis is not supported
272      */
273     public Object getParentNode(Object contextNode) throws UnsupportedAxisException
274     {
275         Iterator iter = getParentAxisIterator( contextNode );
276         if ( iter != null && iter.hasNext() )
277         {
278             return iter.next();
279         }
280         return null;
281     }
282 
283     /***
284      *  Default implementation that always returns null. Override in subclass
285      *  if the subclass can load documents. 
286      *
287      * @param url the URL of the document to load
288      *
289      * @return null
290      * @throws FunctionCallException if an error occurs while loading the
291      *    URL; e.g. an I/O error or the document is malformed
292      */
293     public Object getDocument(String url) throws FunctionCallException
294     {
295         return null;
296     }
297 
298     /***
299      *  Default implementation that cannot find elements. Override in subclass
300      *  if subclass does know about attribute types.
301      *
302      *  @param contextNode   a node from the document in which to look for the
303      *                       id
304      *  @param elementId   id to look for
305      *
306      *  @return   null
307      */
308     public Object getElementById(Object contextNode, String elementId)
309     {
310         return null;
311     }
312     
313 }