DOM2Helper


1   /*
2    * Copyright 1999-2004 The Apache Software Foundation.
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *     http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  /*
17   * $Id: DOM2Helper.java,v 1.5 2004/02/17 04:21:14 minchau Exp $
18   */
19  package org.apache.xml.utils;
20  
21  import java.io.IOException  ;
22  
23  import javax.xml.parsers.DocumentBuilder  ;
24  import javax.xml.parsers.DocumentBuilderFactory  ;
25  import javax.xml.parsers.ParserConfigurationException  ;
26  import javax.xml.transform.TransformerException  ;
27  
28  import org.w3c.dom.Attr  ;
29  import org.w3c.dom.Document  ;
30  import org.w3c.dom.Element  ;
31  import org.w3c.dom.Node  ;
32  
33  import org.xml.sax.InputSource  ;
34  
35  /**
36   * @deprecated Since the introduction of the DTM, this class will be removed.
37   * This class provides a DOM level 2 "helper", which provides services currently 
38   * not provided be the DOM standard.
39   */
40  public class DOM2Helper extends DOMHelper
41  {
42  
43    /**
44     * Construct an instance.
45     */
46    public DOM2Helper(){}
47  
48    /**
49     * Check node to see if it was created by a DOM implementation
50     * that this helper is intended to support. This is currently
51     * disabled, and assumes all nodes are acceptable rather than checking
52     * that they implement org.apache.xerces.dom.NodeImpl.
53     *
54     * @param node The node to be tested.
55     *
56     * @throws TransformerException if the node is not one which this
57     * DOM2Helper can support. If we return without throwing the exception,
58     * the node is compatable.
59     * @xsl.usage internal
60     */
61    public void checkNode(Node   node) throws TransformerException  
62    {
63  
64      // if(!(node instanceof org.apache.xerces.dom.NodeImpl))
65      //  throw new TransformerException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_XERCES_CANNOT_HANDLE_NODES, new Object[]{((Object)node).getClass()})); //"DOM2Helper can not handle nodes of type"
66      //+((Object)node).getClass());
67    }
68  
69    /**
70     * Returns true if the DOM implementation handled by this helper
71     * supports the SAX ContentHandler interface.
72     *
73     * @return true (since Xerces does).
74     */
75    public boolean supportsSAX()
76    {
77      return true;
78    }
79  
80    /** Field m_doc: Document Node for the document this helper is currently
81     * accessing or building
82     * @see #setDocument
83     * @see #getDocument
84     *  */
85    private Document   m_doc;
86  
87    /**
88     * Specify which document this helper is currently operating on.
89     *    
90     * @param doc The DOM Document node for this document.
91     * @see #getDocument
92     */
93    public void setDocument(Document   doc)
94    {
95      m_doc = doc;
96    }
97  
98    /**
99     * Query which document this helper is currently operating on.
100    *    
101    * @return The DOM Document node for this document.
102    * @see #setDocument
103    */
104   public Document   getDocument()
105   {
106     return m_doc;
107   }
108 
109   /**
110    * Parse an XML document.
111    *
112    * <p>Right now the Xerces DOMParser class is used.  This needs
113    * fixing, either via jaxp, or via some other, standard method.</p>
114    *
115    * <p>The application can use this method to instruct the SAX parser
116    * to begin parsing an XML document from any valid input
117    * source (a character stream, a byte stream, or a URI).</p>
118    *
119    * <p>Applications may not invoke this method while a parse is in
120    * progress (they should create a new Parser instead for each
121    * additional XML document).  Once a parse is complete, an
122    * application may reuse the same Parser object, possibly with a
123    * different input source.</p>
124    *
125    * @param source The input source for the top-level of the
126    *        XML document.
127    *
128    * @throws TransformerException if any checked exception is thrown.
129    * @xsl.usage internal
130    */
131   public void parse(InputSource   source) throws TransformerException  
132   {
133 
134     try
135     {
136 
137       // I guess I should use JAXP factory here... when it's legal.
138       // org.apache.xerces.parsers.DOMParser parser 
139       //  = new org.apache.xerces.parsers.DOMParser();
140       DocumentBuilderFactory   builderFactory =
141         DocumentBuilderFactory.newInstance();
142 
143       builderFactory.setNamespaceAware(true);
144       builderFactory.setValidating(true);
145 
146       DocumentBuilder   parser = builderFactory.newDocumentBuilder();
147 
148       /*
149       // domParser.setFeature("http://apache.org/xml/features/dom/create-entity-ref-nodes", getShouldExpandEntityRefs()? false : true);
150       if(m_useDOM2getNamespaceURI)
151       {
152       parser.setFeature("http://apache.org/xml/features/dom/defer-node-expansion", true);
153       parser.setFeature("http://xml.org/sax/features/namespaces", true);
154       }
155       else
156       {
157       parser.setFeature("http://apache.org/xml/features/dom/defer-node-expansion", false);
158       }
159 
160       parser.setFeature("http://apache.org/xml/features/allow-java-encodings", true);
161       */
162 
163       parser.setErrorHandler(
164         new org.apache.xml.utils.DefaultErrorHandler());
165 
166       // if(null != m_entityResolver)
167       // {
168       // System.out.println("Setting the entity resolver.");
169       //  parser.setEntityResolver(m_entityResolver);
170       // }
171       setDocument(parser.parse(source));
172     }
173     catch (org.xml.sax.SAXException   se)
174     {
175       throw new TransformerException  (se);
176     }
177     catch (ParserConfigurationException   pce)
178     {
179       throw new TransformerException  (pce);
180     }
181     catch (IOException   ioe)
182     {
183       throw new TransformerException  (ioe);
184     }
185 
186     // setDocument(((org.apache.xerces.parsers.DOMParser)parser).getDocument());
187   }
188 
189   /**
190    * Given an XML ID, return the element. This requires assistance from the
191    * DOM and parser, and is meaningful only in the context of a DTD 
192    * or schema which declares attributes as being of type ID. This
193    * information may or may not be available in all parsers, may or
194    * may not be available for specific documents, and may or may not
195    * be available when validation is not turned on.
196    *
197    * @param id The ID to search for, as a String.
198    * @param doc The document to search within, as a DOM Document node.
199    * @return DOM Element node with an attribute of type ID whose value
200    * uniquely matches the requested id string, or null if there isn't
201    * such an element or if the DOM can't answer the question for other
202    * reasons.
203    */
204   public Element   getElementByID(String   id, Document   doc)
205   {
206     return doc.getElementById(id);
207   }
208 
209   /**
210    * Figure out whether node2 should be considered as being later
211    * in the document than node1, in Document Order as defined
212    * by the XPath model. This may not agree with the ordering defined
213    * by other XML applications.
214    * <p>
215    * There are some cases where ordering isn't defined, and neither are
216    * the results of this function -- though we'll generally return true.
217    * <p>
218    * TODO: Make sure this does the right thing with attribute nodes!!!
219    *
220    * @param node1 DOM Node to perform position comparison on.
221    * @param node2 DOM Node to perform position comparison on .
222    * 
223    * @return false if node2 comes before node1, otherwise return true.
224    * You can think of this as 
225    * <code>(node1.documentOrderPosition &lt;= node2.documentOrderPosition)</code>.
226    */
227   public static boolean isNodeAfter(Node   node1, Node   node2)
228   {
229 
230     // Assume first that the nodes are DTM nodes, since discovering node 
231     // order is massivly faster for the DTM.
232     if(node1 instanceof DOMOrder && node2 instanceof DOMOrder)
233     {
234       int index1 = ((DOMOrder) node1).getUid();
235       int index2 = ((DOMOrder) node2).getUid();
236 
237       return index1 <= index2;
238     }
239     else
240     {
241 
242       // isNodeAfter will return true if node is after countedNode 
243       // in document order. The base isNodeAfter is sloooow (relatively).
244       return DOMHelper.isNodeAfter(node1, node2);
245     }
246   }
247 
248   /**
249    * Get the XPath-model parent of a node.  This version takes advantage
250    * of the DOM Level 2 Attr.ownerElement() method; the base version we
251    * would otherwise inherit is prepared to fall back on exhaustively
252    * walking the document to find an Attr's parent.
253    *
254    * @param node Node to be examined
255    *
256    * @return the DOM parent of the input node, if there is one, or the
257    * ownerElement if the input node is an Attr, or null if the node is
258    * a Document, a DocumentFragment, or an orphan.
259    */
260   public static Node   getParentOfNode(Node   node)
261   {
262           Node   parent=node.getParentNode();
263           if(parent==null && (Node.ATTRIBUTE_NODE == node.getNodeType()) )
264            parent=((Attr  ) node).getOwnerElement();
265           return parent;
266   }
267 
268   /**
269    * Returns the local name of the given node, as defined by the
270    * XML Namespaces specification. This is prepared to handle documents
271    * built using DOM Level 1 methods by falling back upon explicitly
272    * parsing the node name.
273    *
274    * @param n Node to be examined
275    *
276    * @return String containing the local name, or null if the node
277    * was not assigned a Namespace.
278    */
279   public String   getLocalNameOfNode(Node   n)
280   {
281 
282     String   name = n.getLocalName();
283 
284     return (null == name) ? super.getLocalNameOfNode(n) : name;
285   }
286 
287   /**
288    * Returns the Namespace Name (Namespace URI) for the given node.
289    * In a Level 2 DOM, you can ask the node itself. Note, however, that
290    * doing so conflicts with our decision in getLocalNameOfNode not
291    * to trust the that the DOM was indeed created using the Level 2
292    * methods. If Level 1 methods were used, these two functions will
293    * disagree with each other.
294    * <p>
295    * TODO: Reconcile with getLocalNameOfNode.
296    *
297    * @param n Node to be examined
298    *
299    * @return String containing the Namespace URI bound to this DOM node
300    * at the time the Node was created.
301    */
302   public String   getNamespaceOfNode(Node   n)
303   {
304     return n.getNamespaceURI();
305   }
306 
307   /** Field m_useDOM2getNamespaceURI is a compile-time flag which
308    *  gates some of the parser options used to build a DOM -- but 
309    * that code is commented out at this time and nobody else
310    * references it, so I've commented this out as well. */
311   //private boolean m_useDOM2getNamespaceURI = false;
312 }
313
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