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1   /*
2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/ext/LocaleFunctionSupport.java,v 1.10 2006/02/05 21:47:42 elharo Exp $
3    * $Revision: 1.10 $
4    * $Date: 2006/02/05 21:47:42 $
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: LocaleFunctionSupport.java,v 1.10 2006/02/05 21:47:42 elharo Exp $
46   */
47  
48  package org.jaxen.function.ext;
49  
50  import java.util.List;
51  import java.util.Locale;
52  import java.util.StringTokenizer;
53  
54  import org.jaxen.Function;
55  import org.jaxen.Navigator;
56  import org.jaxen.function.StringFunction;
57  
58  /***
59   * <p>An abstract base class for Locale-specific extension 
60   * functions. This class provides convenience methods that
61   * can be inherited, specifically to find a Locale from
62   * an XPath function argument value.
63   * </p>
64   *
65   * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
66   */
67  public abstract class LocaleFunctionSupport implements Function
68  {
69  
70      /*** 
71       * Attempts to convert the given function argument value 
72       * into a Locale either via casting, extracting it from a List
73       * or looking up the named Locale using reflection.
74       *
75       * @param value is either a Locale, a List containing a Locale
76       *      or a String containing the name of a Locale
77       *      as defined by the Locale static members.
78       *
79       * @return the Locale for the value or null if one could 
80       *      not be deduced
81       */
82      protected Locale getLocale(Object value, Navigator navigator) 
83      {
84          if (value instanceof Locale)
85          {
86              return (Locale) value;
87          }
88          else if(value instanceof List)
89          {
90              List list = (List) value;
91              if ( ! list.isEmpty() ) 
92              {
93                  return getLocale( list.get(0), navigator );
94              }
95          }
96          else {
97              String text = StringFunction.evaluate( value, navigator );
98              if (text != null && text.length() > 0) 
99              {
100                 return findLocale( text );
101             }
102         }
103         return null;
104     }
105     
106     /*** 
107      * Tries to find a Locale instance by name using 
108      * <a href="http://www.ietf.org/rfc/rfc3066.txt" target="_top">RFC 3066</a>
109      * language tags such as 'en', 'en-US', 'en-US-Brooklyn'.
110      *
111      * @param localeText the RFC 3066 language tag
112      * @return the locale for the given text or null if one could not
113      *      be found 
114      */
115     protected Locale findLocale(String localeText) {
116         StringTokenizer tokens = new StringTokenizer( localeText, "-" );
117         if (tokens.hasMoreTokens())
118         {
119             String language = tokens.nextToken();
120             if (! tokens.hasMoreTokens())
121             {                
122                 return findLocaleForLanguage(language);
123             }
124             else 
125             {
126                 String country = tokens.nextToken();
127                 if (! tokens.hasMoreTokens())
128                 {
129                     return new Locale(language, country);
130                 }
131                 else 
132                 {
133                     String variant = tokens.nextToken();
134                     return new Locale(language, country, variant);
135                 }
136             }
137         }
138         return null;
139     }
140     
141     /*** 
142      * Finds the locale with the given language name with no country
143      * or variant, such as Locale.ENGLISH or Locale.FRENCH
144      *
145      * @param language the language code to look for
146      * @return the locale for the given language or null if one could not
147      *      be found 
148      */
149     protected Locale findLocaleForLanguage(String language) {
150         Locale[] locales = Locale.getAvailableLocales();
151         for ( int i = 0, size = locales.length; i < size; i++ ) 
152         {
153             Locale locale = locales[i];
154             if ( language.equals( locale.getLanguage() ) ) 
155             {
156                 String country = locale.getCountry();
157                 if ( country == null || country.length() == 0 ) 
158                 {
159                     String variant = locale.getVariant();
160                     if ( variant == null || variant.length() == 0 ) 
161                     {
162                         return locale;
163                     }
164                 }
165             }
166         }    
167         return null;
168     }
169 }