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1   /*
2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/SimpleVariableContext.java,v 1.19 2006/06/03 20:19:54 elharo Exp $
3    * $Revision: 1.19 $
4    * $Date: 2006/06/03 20:19:54 $
5    *
6    * ====================================================================
7    *
8    * Copyright 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 are
13   * met:
14   * 
15   *   * Redistributions of source code must retain the above copyright
16   *     notice, this list of conditions and the following disclaimer.
17   * 
18   *   * Redistributions in binary form must reproduce the above copyright
19   *     notice, this list of conditions and the following disclaimer in the
20   *     documentation and/or other materials provided with the distribution.
21   * 
22   *   * Neither the name of the Jaxen Project nor the names of its
23   *     contributors may be used to endorse or promote products derived 
24   *     from this software without specific prior written permission.
25   * 
26   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
27   * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28   * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
29   * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
30   * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
31   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
32   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
33   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
34   * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
35   * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
36   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37   *
38   * ====================================================================
39   * This software consists of voluntary contributions made by many 
40   * individuals on behalf of the Jaxen Project and was originally 
41   * created by bob mcwhirter <bob@werken.com> and 
42   * James Strachan <jstrachan@apache.org>.  For more information on the 
43   * Jaxen Project, please see <http://www.jaxen.org/>.
44   * 
45   * $Id: SimpleVariableContext.java,v 1.19 2006/06/03 20:19:54 elharo Exp $
46   */
47  
48  
49  package org.jaxen;
50  
51  import java.io.Serializable;
52  import java.util.HashMap;
53  import java.util.Map;
54  
55  /*** Simple default implementation for <code>VariableContext</code>.
56   *
57   *  <p>
58   *  This is a simple table-based key-lookup implementation
59   *  for <code>VariableContext</code> which can be programmatically
60   *  extended by setting additional variables.
61   *  </p>
62   *
63   *  @author <a href="mailto:bob@werken.com">bob mcwhirter</a>
64   */
65  public class SimpleVariableContext implements VariableContext, Serializable
66  {
67      /***
68       * 
69       */
70      private static final long serialVersionUID = 961322093794516518L;
71      /*** Table of variable bindings. */
72      private Map variables;
73  
74      /*** Construct.
75       *
76       *  <p>
77       *  Create a new empty variable context.
78       *  </p>
79       */
80      public SimpleVariableContext()
81      {
82          variables = new HashMap();
83      }
84  
85      /*** Set the value associated with a variable.
86       *
87       *  <p>
88       *  This method sets a variable that is 
89       *  associated with a particular namespace.
90       *  These variables appear such as <code>$prefix:foo</code>
91       *  in an XPath expression.  Prefix to URI resolution
92       *  is the responsibility of a <code>NamespaceContext</code>.
93       *  Variables within a <code>VariableContext</code> are
94       *  referred to purely based upon their namespace URI,
95       *  if any.
96       *  </p>
97       *
98       *  @param namespaceURI the namespace URI of the variable
99       *  @param localName the local name of the variable
100      *  @param value The value to be bound to the variable
101      */
102     public void setVariableValue( String namespaceURI,
103                                   String localName,
104                                   Object value )
105     {
106         this.variables.put( new QualifiedName(namespaceURI, localName),
107                             value );
108     }
109 
110     /*** Set the value associated with a variable.
111      *
112      *  <p>
113      *  This method sets a variable that is <strong>not</strong>
114      *  associated with any particular namespace.
115      *  These variables look like <code>$foo</code>
116      *  in an XPath expression.
117      *  </p>
118      *
119      *  @param localName the local name of the variable
120      *  @param value the value to be bound to the variable
121      */
122     public void setVariableValue( String localName,
123                                   Object value )
124     {
125         this.variables.put( new QualifiedName(null, localName), value );
126     }
127 
128     public Object getVariableValue( String namespaceURI,
129                                     String prefix,
130                                     String localName )
131         throws UnresolvableException
132     {
133         QualifiedName key = new QualifiedName( namespaceURI, localName );
134 
135         if ( this.variables.containsKey(key) )
136         {
137             return this.variables.get( key );
138         }
139         else
140         {
141             throw new UnresolvableException( "Variable " + key.getClarkForm() );
142         }
143     }
144 }