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1   /*
2    * $Header$
3    * $Revision: 1168 $
4    * $Date: 2006-07-03 04:58:31 -0700 (Mon, 03 Jul 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: NamespaceContext.java 1168 2006-07-03 11:58:31Z elharo $
46   */
47  
48  
49  package org.jaxen;
50  
51  /** Resolves namespace prefixes to namespace URIs.
52   *
53   *  <p>
54   *  The prefixes used within an XPath expression are
55   *  independent of those used within any target document.
56   *  When evaluating an XPath against a document, only
57   *  the resolved namespace URIs are compared, not their
58   *  prefixes.
59   *  </p>
60   *
61   *  <p>
62   *  A <code>NamespaceContext</code> is responsible for
63   *  translating prefixes as they appear in XPath expressions
64   *  into URIs for comparison.  A document's prefixes are
65   *  resolved internal to the document based upon its own
66   *  namespace nodes.
67   *  </p>
68   *  
69   *  <p>
70   *  Implementations of this interface should implement <code>Serializable</code>.
71   *  </p>
72   *
73   *  @see BaseXPath
74   *  @see Navigator#getElementNamespaceUri
75   *  @see Navigator#getAttributeNamespaceUri
76   *
77   *  @author <a href="mailto:bob@werken.com">bob mcwhirter</a>
78   */
79  public interface NamespaceContext
80  {
81      /** Translate the provided namespace prefix into 
82       *  the matching bound namespace URI.
83       *
84       *  <p>
85       *  In XPath, there is no such thing as a 'default namespace'.
86       *  The empty prefix <strong>always</strong> resolves to the empty
87       *  namespace URI. This method should return null for the
88       *  empty prefix.
89       *  Similarly, the prefix "xml" always resolves to
90       *  the URI "http://www.w3.org/XML/1998/namespace".
91       *  </p>
92       *
93       *  @param prefix the namespace prefix to resolve
94       *
95       *  @return the namespace URI bound to the prefix; or null if there
96       *     is no such namespace 
97       */
98      String translateNamespacePrefixToUri(String prefix);
99  }