XPathExpressionImpl


1   /*
2    * Copyright 2002-2005 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: XPathExpressionImpl.java,v 1.2.4.1 2005/09/10 04:06:55 jeffsuttor Exp $
18   */
19  
20  
21  package com.sun.org.apache.xpath.internal.domapi;
22  
23  import javax.xml.transform.TransformerException  ;
24  
25  import com.sun.org.apache.xpath.internal.XPath;
26  import com.sun.org.apache.xpath.internal.XPathContext;
27  import com.sun.org.apache.xpath.internal.objects.XObject;
28  import com.sun.org.apache.xpath.internal.res.XPATHErrorResources;
29  import com.sun.org.apache.xpath.internal.res.XPATHMessages;
30  import org.w3c.dom.DOMException  ;
31  import org.w3c.dom.Document  ;
32  import org.w3c.dom.Node  ;
33  import org.w3c.dom.xpath.XPathException;
34  import org.w3c.dom.xpath.XPathExpression;
35  import org.w3c.dom.xpath.XPathNamespace;
36  
37  /**
38   * 
39   * The class provides an implementation of XPathExpression according 
40   * to the DOM L3 XPath Specification, Working Group Note 26 February 2004.
41   *
42   * <p>See also the <a HREF='http://www.w3.org/TR/2004/NOTE-DOM-Level-3-XPath-20040226'>Document Object Model (DOM) Level 3 XPath Specification</a>.</p>
43   *
44   * <p>The <code>XPathExpression</code> interface represents a parsed and resolved 
45   * XPath expression.</p>
46   * 
47   * @see org.w3c.dom.xpath.XPathExpression
48   *  
49   * @xsl.usage internal
50   */
51  class XPathExpressionImpl implements XPathExpression {
52  
53    /**
54     * The xpath object that this expression wraps
55     */
56    final private XPath m_xpath;
57    
58    /**
59     * The document to be searched to parallel the case where the XPathEvaluator
60     * is obtained by casting a Document.
61     */  
62    final private Document   m_doc;  
63  
64      /**
65       * Constructor for XPathExpressionImpl.
66       * 
67       * @param xpath The wrapped XPath object.
68       * @param doc The document to be searched, to parallel the case where''
69       *            the XPathEvaluator is obtained by casting the document.
70       */
71      XPathExpressionImpl(XPath xpath, Document   doc) {
72          m_xpath = xpath;
73          m_doc = doc;
74      }
75  
76      /**
77       *
78       * This method provides an implementation XPathResult.evaluate according 
79       * to the DOM L3 XPath Specification, Working Group Note 26 February 2004.
80       *
81       * <p>See also the <a HREF='http://www.w3.org/TR/2004/NOTE-DOM-Level-3-XPath-20040226'>Document Object Model (DOM) Level 3 XPath Specification</a>.</p>
82       * 
83       * <p>Evaluates this XPath expression and returns a result.</p>
84       * @param contextNode The <code>context</code> is context node for the 
85       *   evaluation of this XPath expression.If the XPathEvaluator was 
86       *   obtained by casting the <code>Document</code> then this must be 
87       *   owned by the same document and must be a <code>Document</code>, 
88       *   <code>Element</code>, <code>Attribute</code>, <code>Text</code>, 
89       *   <code>CDATASection</code>, <code>Comment</code>, 
90       *   <code>ProcessingInstruction</code>, or <code>XPathNamespace</code> 
91       *   node.If the context node is a <code>Text</code> or a 
92       *   <code>CDATASection</code>, then the context is interpreted as the 
93       *   whole logical text node as seen by XPath, unless the node is empty 
94       *   in which case it may not serve as the XPath context.
95       * @param type If a specific <code>type</code> is specified, then the 
96       *   result will be coerced to return the specified type relying on 
97       *   XPath conversions and fail if the desired coercion is not possible. 
98       *   This must be one of the type codes of <code>XPathResult</code>.
99      *  @param result The <code>result</code> specifies a specific result 
100      *   object which may be reused and returned by this method. If this is 
101      *   specified as <code>null</code>or the implementation does not reuse 
102      *   the specified result, a new result object will be constructed and 
103      *   returned.For XPath 1.0 results, this object will be of type 
104      *   <code>XPathResult</code>.
105      * @return The result of the evaluation of the XPath expression.For XPath 
106      *   1.0 results, this object will be of type <code>XPathResult</code>.
107      * @exception XPathException
108      *   TYPE_ERR: Raised if the result cannot be converted to return the 
109      *   specified type.
110      * @exception DOMException
111      *   WRONG_DOCUMENT_ERR: The Node is from a document that is not supported 
112      *   by the XPathEvaluator that created this 
113      *   <code>XPathExpression</code>.
114      *   <br>NOT_SUPPORTED_ERR: The Node is not a type permitted as an XPath 
115      *   context node.   
116      * 
117      * @see org.w3c.dom.xpath.XPathExpression#evaluate(Node, short, XPathResult)
118      * @xsl.usage internal
119      */
120     public Object   evaluate(
121         Node   contextNode,
122         short type,
123         Object   result)
124         throws XPathException, DOMException   {
125             
126         // If the XPathEvaluator was determined by "casting" the document    
127         if (m_doc != null) {
128         
129             // Check that the context node is owned by the same document
130             if ((contextNode != m_doc) && (!contextNode.getOwnerDocument().equals(m_doc))) {
131                 String   fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_WRONG_DOCUMENT, null);       
132                 throw new DOMException  (DOMException.WRONG_DOCUMENT_ERR, fmsg);
133             }
134             
135             // Check that the context node is an acceptable node type
136             short nodeType = contextNode.getNodeType();
137             if ((nodeType != Document.DOCUMENT_NODE) &&
138                 (nodeType != Document.ELEMENT_NODE) && 
139                 (nodeType != Document.ATTRIBUTE_NODE) &&
140                 (nodeType != Document.TEXT_NODE) &&
141                 (nodeType != Document.CDATA_SECTION_NODE) &&
142                 (nodeType != Document.COMMENT_NODE) &&
143                 (nodeType != Document.PROCESSING_INSTRUCTION_NODE) &&
144                 (nodeType != XPathNamespace.XPATH_NAMESPACE_NODE)) {
145                     String   fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_WRONG_NODETYPE, null);       
146                     throw new DOMException  (DOMException.NOT_SUPPORTED_ERR, fmsg);
147             }
148         }
149             
150         //     
151         // If the type is not a supported type, throw an exception and be
152         // done with it!
153         if (!XPathResultImpl.isValidType(type)) {
154             String   fmsg = XPATHMessages.createXPATHMessage(XPATHErrorResources.ER_INVALID_XPATH_TYPE, new Object  [] {new Integer  (type)});       
155             throw new XPathException(XPathException.TYPE_ERR,fmsg); // Invalid XPath type argument: {0}               
156         }
157         
158         // Cache xpath context?
159         XPathContext xpathSupport = new XPathContext();
160         
161         // if m_document is not null, build the DTM from the document 
162         if (null != m_doc) {
163             xpathSupport.getDTMHandleFromNode(m_doc);
164         }
165 
166         XObject xobj = null;
167         try {
168             xobj = m_xpath.execute(xpathSupport, contextNode, null);         
169         } catch (TransformerException   te) {
170             // What should we do here?
171             throw new XPathException(XPathException.INVALID_EXPRESSION_ERR,te.getMessageAndLocation()); 
172         }
173 
174         // Create a new XPathResult object
175         // Reuse result object passed in?
176         // The constructor will check the compatibility of type and xobj and
177         // throw an exception if they are not compatible.
178         return new XPathResultImpl(type,xobj,contextNode, m_xpath);
179     }
180 
181 }
182
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