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1   /*
2    * $Header$
3    * $Revision: 1159 $
4    * $Date: 2006-06-03 13:25:34 -0700 (Sat, 03 Jun 2006) $
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: SimpleNamespaceContext.java 1159 2006-06-03 20:25:34Z elharo $
46   */
47  
48  
49  package org.jaxen;
50  
51  import java.io.Serializable;
52  import java.util.HashMap;
53  import java.util.Iterator;
54  import java.util.Map;
55  
56  /**
57   *  Provides mappings from namespace prefix to namespace URI to the XPath
58   *  engine.
59   */
60  public class SimpleNamespaceContext implements NamespaceContext, Serializable
61  {
62      
63      /**
64       * 
65       */
66      private static final long serialVersionUID = -808928409643497762L;
67      // XXX should this prebind the xml prefix?
68      private Map namespaces;
69  
70      /**
71       * Creates a new empty namespace context.
72       */
73      public SimpleNamespaceContext()
74      {
75          this.namespaces = new HashMap();
76      }
77  
78      /**
79       * Creates a new namespace context pre-populated with the specified bindings. 
80       * 
81       * @param namespaces the initial namespace bindings in scope. The keys in this
82       *     must be strings containing the prefixes and the values are strings
83       *     containing the namespace URIs.
84       *     
85       * @throws NullPointerException if the argument is null   
86       * @throws ClassCastException if any keys or values in the map are not strings   
87       */
88      public SimpleNamespaceContext(Map namespaces)
89      {
90          Iterator entries = namespaces.entrySet().iterator();
91          while (entries.hasNext()) {
92              Map.Entry entry = (Map.Entry) entries.next();
93              if (! (entry.getKey() instanceof String)
94                || ! (entry.getValue() instanceof String)) {
95                  throw new ClassCastException("Non-string namespace binding");
96              }
97          }
98          this.namespaces = new HashMap(namespaces);
99      }
100 
101     /**
102      *  Adds all the namespace declarations that are in scope on the given
103      *  element. In the case of an XSLT stylesheet, this would be the element
104      *  that has the XPath expression in one of its attributes; e.g.
105      *  <code>&lt;xsl:if test="condition/xpath/expression"&gt;</code>.
106      *
107      *  @param nav  the navigator for use in conjunction with
108      *              <code>element</code>
109      *  @param element the element to copy the namespaces from
110      *  @throws UnsupportedAxisException if the navigator does not support the 
111      *     namespace axis
112      */
113     public void addElementNamespaces( Navigator nav, Object element )
114         throws UnsupportedAxisException
115     {
116         Iterator namespaceAxis = nav.getNamespaceAxisIterator( element );
117 
118         while ( namespaceAxis.hasNext() ) {
119             Object namespace = namespaceAxis.next();
120             String prefix = nav.getNamespacePrefix( namespace );
121             String uri = nav.getNamespaceStringValue( namespace );
122             if ( translateNamespacePrefixToUri(prefix) == null ) {
123                 addNamespace( prefix, uri );
124             }
125         }
126     }    
127 
128     // ???? What if prefix or URI is null, or both?
129     /**
130      * Binds a prefix to a URI in this context.
131      * 
132      * @param prefix the namespace prefix
133      * @param URI    the namespace URI
134      */
135     public void addNamespace(String prefix, String URI)
136     {
137         this.namespaces.put( prefix, URI );
138     }
139 
140     public String translateNamespacePrefixToUri(String prefix)
141     {
142         if ( this.namespaces.containsKey( prefix ) )
143         {
144             return (String) this.namespaces.get( prefix );
145         }
146 
147         return null;
148     }
149 }