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1   /*
2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/ext/LocaleFunctionSupport.java,v 1.8 2005/06/16 12:51:23 elharo Exp $
3    * $Revision: 1.8 $
4    * $Date: 2005/06/16 12:51:23 $
5    *
6    * ====================================================================
7    *
8    * Copyright (C) 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
13   * are met:
14   * 
15   * 1. Redistributions of source code must retain the above copyright
16   *    notice, this list of conditions, and the following disclaimer.
17   *
18   * 2. Redistributions in binary form must reproduce the above copyright
19   *    notice, this list of conditions, and the disclaimer that follows 
20   *    these conditions in the documentation and/or other materials 
21   *    provided with the distribution.
22   *
23   * 3. The name "Jaxen" must not be used to endorse or promote products
24   *    derived from this software without prior written permission.  For
25   *    written permission, please contact license@jaxen.org.
26   * 
27   * 4. Products derived from this software may not be called "Jaxen", nor
28   *    may "Jaxen" appear in their name, without prior written permission
29   *    from the Jaxen Project Management (pm@jaxen.org).
30   * 
31   * In addition, we request (but do not require) that you include in the 
32   * end-user documentation provided with the redistribution and/or in the 
33   * software itself an acknowledgement equivalent to the following:
34   *     "This product includes software developed by the
35   *      Jaxen Project (http://www.jaxen.org/)."
36   * Alternatively, the acknowledgment may be graphical using the logos 
37   * available at http://www.jaxen.org/
38   *
39   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
40   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
41   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
42   * DISCLAIMED.  IN NO EVENT SHALL THE Jaxen AUTHORS OR THE PROJECT
43   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
44   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
45   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
46   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
47   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
48   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
49   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
50   * SUCH DAMAGE.
51   *
52   * ====================================================================
53   * This software consists of voluntary contributions made by many 
54   * individuals on behalf of the Jaxen Project and was originally 
55   * created by bob mcwhirter <bob@werken.com> and 
56   * James Strachan <jstrachan@apache.org>.  For more information on the 
57   * Jaxen Project, please see <http://www.jaxen.org/>.
58   * 
59   * $Id: LocaleFunctionSupport.java,v 1.8 2005/06/16 12:51:23 elharo Exp $
60   */
61  
62  package org.jaxen.function.ext;
63  
64  import java.util.List;
65  import java.util.Locale;
66  import java.util.StringTokenizer;
67  
68  import org.jaxen.Function;
69  import org.jaxen.Navigator;
70  import org.jaxen.function.StringFunction;
71  
72  /***
73   * <p>An abstract base class for Locale-specific extension 
74   * functions. This class provides convenience methods that
75   * can be inherited, specifically to find a Locale from
76   * an XPath function argument value.
77   * </p>
78   *
79   * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
80   */
81  public abstract class LocaleFunctionSupport implements Function
82  {
83  
84      /*** 
85       * Attempts to convert the given function argument value 
86       * into a Locale either via casting, extracting it from a List
87       * or looking up the named Locale using reflection.
88       *
89       * @param value is either a Locale, a List containing a Locale
90       *      or a String containing the name of a Locale
91       *      as defined by the Locale static members.
92       *
93       * @return the Locale for the value or null if one could 
94       *      not be deduced
95       */
96      protected Locale getLocale(Object value, Navigator navigator) 
97      {
98          if (value instanceof Locale)
99          {
100             return (Locale) value;
101         }
102         else if(value instanceof List)
103         {
104             List list = (List) value;
105             if ( ! list.isEmpty() ) 
106             {
107                 return getLocale( list.get(0), navigator );
108             }
109         }
110         else {
111             String text = StringFunction.evaluate( value, navigator );
112             if (text != null && text.length() > 0) 
113             {
114                 return findLocale( text );
115             }
116         }
117         return null;
118     }
119     
120     /*** 
121      * Tries to find a Locale instance by name using 
122      * <a href="http://www.ietf.org/rfc/rfc3066.txt" target="_top">RFC 3066</a>
123      * language tags such as 'en', 'en-US', 'en-US-Brooklyn'.
124      *
125      * @param localeText the RFC 3066 language tag
126      * @return the locale for the given text or null if one could not
127      *      be found 
128      */
129     protected Locale findLocale(String localeText) {
130         StringTokenizer tokens = new StringTokenizer( localeText, "-" );
131         if (tokens.hasMoreTokens())
132         {
133             String language = tokens.nextToken();
134             if (! tokens.hasMoreTokens())
135             {                
136                 return findLocaleForLanguage(language);
137             }
138             else 
139             {
140                 String country = tokens.nextToken();
141                 if (! tokens.hasMoreTokens())
142                 {
143                     return new Locale(language, country);
144                 }
145                 else 
146                 {
147                     String variant = tokens.nextToken();
148                     return new Locale(language, country, variant);
149                 }
150             }
151         }
152         return null;
153     }
154     
155     /*** 
156      * Finds the locale with the given language name with no country
157      * or variant, such as Locale.ENGLISH or Locale.FRENCH
158      *
159      * @param language the language code to look for
160      * @return the locale for the given language or null if one could not
161      *      be found 
162      */
163     protected Locale findLocaleForLanguage(String language) {
164         Locale[] locales = Locale.getAvailableLocales();
165         for ( int i = 0, size = locales.length; i < size; i++ ) 
166         {
167             Locale locale = locales[i];
168             if ( language.equals( locale.getLanguage() ) ) 
169             {
170                 String country = locale.getCountry();
171                 if ( country == null || country.length() == 0 ) 
172                 {
173                     String variant = locale.getVariant();
174                     if ( variant == null || variant.length() == 0 ) 
175                     {
176                         return locale;
177                     }
178                 }
179             }
180         }    
181         return null;
182     }
183 }