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Java > Open Source Codes > org > jaxen > Context


1 package org.jaxen;
2
3 /*
4  $Id: Context.java,v 1.14 2005/06/01 11:19:23 elharo Exp $
5
6  Copyright 2003 (C) The Werken Company. All Rights Reserved.
7  
8  Redistribution and use of this software and associated documentation
9  ("Software"), with or without modification, are permitted provided
10  that the following conditions are met:
11
12  1. Redistributions of source code must retain copyright
13     statements and notices. Redistributions must also contain a
14     copy of this document.
15  
16  2. Redistributions in binary form must reproduce the
17     above copyright notice, this list of conditions and the
18     following disclaimer in the documentation and/or other
19     materials provided with the distribution.
20  
21  3. The name "jaxen" must not be used to endorse or promote
22     products derived from this Software without prior written
23     permission of The Werken Company. For written permission,
24     please contact bob@werken.com.
25  
26  4. Products derived from this Software may not be called "jaxen"
27     nor may "jaxen" appear in their names without prior written
28     permission of The Werken Company. "jaxen" is a registered
29     trademark of The Werken Company.
30  
31  5. Due credit should be given to The Werken Company.
32     (http://jaxen.werken.com/).
33  
34  THIS SOFTWARE IS PROVIDED BY THE WERKEN COMPANY AND CONTRIBUTORS
35  ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
36  NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
37  FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
38  THE WERKEN COMPANY OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
39  INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
40  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
41  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
42  HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
43  STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
44  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
45  OF THE POSSIBILITY OF SUCH DAMAGE.
46
47  */
48
49 import java.io.Serializable JavaDoc;
50 import java.util.ArrayList JavaDoc;
51 import java.util.Collections JavaDoc;
52 import java.util.List JavaDoc;
53
54 /** Wrapper around implementation-specific objects used
55  * as the context of an expression evaluation.
56  *
57  * <p>
58  * <strong>NOTE:</strong> This class is not typically used directly,
59  * but is exposed for writers of implementation-specific
60  * XPath packages.
61  * </p>
62  *
63  * <p>
64  * The <code>Context</code> bundles utilities together
65  * for evaluation of the expression. It wraps the provided
66  * objects for ease-of-passage through the expression AST.
67  * </p>
68  *
69  * @see ContextSupport
70  * @see BaseXPath
71  * @see org.jaxen.dom4j.Dom4jXPath XPath for dom4j
72  * @see org.jaxen.jdom.JDOMXPath XPath for JDOM
73  * @see org.jaxen.dom.DOMXPath XPath for W3C DOM
74  *
75  * @author <a HREF="mailto:bob@werken.com">bob mcwhirter</a>
76  */
77 public class Context
78     implements Serializable JavaDoc
79 {
80     // ----------------------------------------------------------------------
81 // Instance members
82 // ----------------------------------------------------------------------
83
84     /** Context-support */
85     private ContextSupport contextSupport;
86
87     /** Context node-set */
88     private List JavaDoc nodeSet;
89
90     /** Current context size */
91     private int size;
92
93     /** Current context position */
94     private int position;
95
96     // ----------------------------------------------------------------------
97 // Constructors
98 // ----------------------------------------------------------------------
99
100     /** Create a new context.
101      *
102      * @param contextSupport the context-support
103      */
104     public Context(ContextSupport contextSupport)
105     {
106         this.contextSupport = contextSupport;
107         this.nodeSet = Collections.EMPTY_LIST;
108     }
109     
110     // ----------------------------------------------------------------------
111 // Instance methods
112 // ----------------------------------------------------------------------
113
114     /** Set the context node-set.
115      *
116      * @param nodeSet the context node-set
117      */
118     public void setNodeSet(List JavaDoc nodeSet)
119     {
120         this.nodeSet = nodeSet;
121     }
122
123     /** Retrieve the context node-set.
124      *
125      * @return the context node-set
126      */
127     public List JavaDoc getNodeSet()
128     {
129         return this.nodeSet;
130     }
131
132     /** Set the <code>ContextSupport</code>.
133      *
134      * @param contextSupport the context-support
135      */
136     public void setContextSupport(ContextSupport contextSupport)
137     {
138         this.contextSupport = contextSupport;
139     }
140
141     /** Retrieve the <code>ContextSupport</code>.
142      *
143      * @return the context-support
144      */
145     public ContextSupport getContextSupport()
146     {
147         return this.contextSupport;
148     }
149
150     /** Retrieve the current <code>Navigator</code>.
151      *
152      * @return the navigator
153      */
154     public Navigator getNavigator()
155     {
156         return getContextSupport().getNavigator();
157     }
158
159     /** Translate a namespace prefix to its URI.
160      *
161      * @param prefix the prefix
162      *
163      * @return the namespace URI mapped to the prefix
164      */
165     public String JavaDoc translateNamespacePrefixToUri(String JavaDoc prefix)
166     {
167         return getContextSupport().translateNamespacePrefixToUri( prefix );
168     }
169
170     /** Retrieve a variable value.
171      *
172      * @param namespaceURI the function namespace URI
173      * @param prefix the function prefix
174      * @param localName the function name
175      *
176      * @return the variable value
177      *
178      * @throws UnresolvableException if unable to locate a bound variable
179      */
180     public Object JavaDoc getVariableValue(String JavaDoc namespaceURI,
181                                    String JavaDoc prefix,
182                                    String JavaDoc localName)
183         throws UnresolvableException
184     {
185         return getContextSupport().getVariableValue( namespaceURI,
186                                                      prefix,
187                                                      localName );
188     }
189
190     /** Retrieve a <code>Function</code>.
191      *
192      * @param namespaceURI the function namespace URI
193      * @param prefix the function prefix
194      * @param localName the function name
195      *
196      * @return the function object
197      *
198      * @throws UnresolvableException if unable to locate a bound function
199      */
200     public Function getFunction(String JavaDoc namespaceURI,
201                                 String JavaDoc prefix,
202                                 String JavaDoc localName)
203         throws UnresolvableException
204     {
205         return getContextSupport().getFunction( namespaceURI,
206                                                 prefix,
207                                                 localName );
208     }
209
210     // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
211 // Properties
212 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
213
214     /** Set the current size in the context node-set.
215      *
216      * @param size the size
217      */
218     public void setSize(int size)
219     {
220         this.size = size;
221     }
222
223     /** Retrieve the size of the context node-set.
224      *
225      * @return the size
226      */
227     public int getSize()
228     {
229         return this.size;
230     }
231
232     /** Set the current position in the context node-set.
233      *
234      * @param position the position
235      */
236     public void setPosition(int position)
237     {
238         this.position = position;
239     }
240
241     /** Retrieve current position in the context node-set.
242      *
243      * @return the current position
244      */
245     public int getPosition()
246     {
247         return this.position;
248     }
249
250     // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
251 // Helpers
252 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
253
254     /** Create a type-safe shallow copy.
255      *
256      * @return the duplicate
257      */
258     public Context duplicate()
259     {
260         Context dupe = new Context( getContextSupport() );
261
262         List JavaDoc thisNodeSet = getNodeSet();
263
264         if ( thisNodeSet != null )
265         {
266             List JavaDoc dupeNodeSet = new ArrayList JavaDoc( thisNodeSet.size() );
267             dupeNodeSet.addAll( thisNodeSet );
268             dupe.setNodeSet( dupeNodeSet );
269         }
270
271         return dupe;
272     }
273 }
274
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