View Javadoc

    1   /*
    2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/LangFunction.java,v 1.12 2005/06/28 13:44:45 elharo Exp $
    3    * $Revision: 1.12 $
    4    * $Date: 2005/06/28 13:44:45 $
    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: LangFunction.java,v 1.12 2005/06/28 13:44:45 elharo Exp $
    60   */
    61
    62
    63  package org.jaxen.function;
    64
    65  import java.util.Iterator;
    66  import java.util.List;
    67
    68  import org.jaxen.Context;
    69  import org.jaxen.Function;
    70  import org.jaxen.FunctionCallException;
    71  import org.jaxen.Navigator;
    72  import org.jaxen.UnsupportedAxisException;
    73
    74  /***
    75   * <p>
    76   * <b>4.3</b> <code><i>boolean</i> lang(<i>string</i>)</code>
    77   * </p>
    78   *
    79   * <blockquote src="http://www.w3.org/TR/xpath#function-lang">
    80   * <p>
    81   * The <b>lang</b> function returns true or false depending on whether
    82   * the language of the context node as specified by
    83   * <code>xml:lang</code> attributes is the same as or is a sublanguage
    84   * of the language specified by the argument string. The language of the
    85   * context node is determined by the value of the <code>xml:lang</code>
    86   *
    87   * attribute on the context node, or, if the context node has no
    88   * <code>xml:lang</code> attribute, by the value of the
    89   * <code>xml:lang</code> attribute on the nearest ancestor of the
    90   * context node that has an <code>xml:lang</code> attribute. If there
    91   * is no such attribute, then <b><a href="#function-lang">lang</a></b>
    92   * returns false. If there is such an attribute, then <b><a
    93   * href="#function-lang">lang</a></b> returns true if the attribute
    94   * value is equal to the argument ignoring case, or if there is some
    95   * suffix starting with <code>-</code> such that the attribute value
    96   * is equal to the argument ignoring that suffix of the attribute value
    97   * and ignoring case. For example, <code>lang("en")</code> would
    98   * return true if the context node is any of these five elements:
    99   * </p>
    100  *
    101  * <pre>
    102  *  &lt;para xml:lang=&quot;en&quot;/&gt;
    103  *  &lt;div xml:lang=&quot;en&quot;&gt;&lt;para/&gt;&lt;/div&gt;
    104  *  &lt;para xml:lang=&quot;EN&quot;/&gt;
    105  *  &lt;para xml:lang=&quot;en-us&quot;/&gt;
    106  * </pre>
    107  *
    108  * </blockquote>
    109  *
    110  * @author Attila Szegedi (szegedia @ freemail.hu)
    111  * @see <a href="http://www.w3.org/TR/xpath#function-lang"
    112  *      target="_top">XPath Specification</a>
    113  */
    114 public class LangFunction implements Function
    115 {
    116     private static final String LANG_LOCALNAME = "lang";
    117     private static final String XMLNS_URI =
    118         "http://www.w3.org/XML/1998/namespace";
    119
    120
    121     /***
    122      * Create a new <code>LangFunction</code> object.
    123      */
    124     public LangFunction() {}
    125
    126
    127     /***
    128      * <p>
    129      * Determines whether or not the context node is written in the language specified
    130      * by the XPath string-value of <code>args.get(0)</code>,
    131      * as determined by the nearest <code>xml:lang</code> attribute in scope.
    132      * </p>
    133      *
    134      * @param context the context in which to evaluate the <code>lang()</code> function
    135      * @param args the arguments to the lang function
    136      * @return a <code>Boolean</code> indicating whether the context node is written in
    137      *     the specified language
    138      * @throws FunctionCallException if <code>args</code> does not have length one
    139      *
    140      */
    141     public Object call(Context context,
    142                        List args) throws FunctionCallException
    143     {
    144         if (args.size() != 1) {
    145             throw new FunctionCallException("lang() requires exactly one argument.");
    146         }
    147
    148         Object arg = args.get(0);
    149
    150         try {
    151             return evaluate(context.getNodeSet(), arg, context.getNavigator() );
    152         }
    153         catch(UnsupportedAxisException e) {
    154             throw new FunctionCallException("Can't evaluate lang()",
    155                                                  e);
    156         }
    157
    158     }
    159
    160     private static Boolean evaluate(List contextNodes, Object lang, Navigator nav)
    161       throws UnsupportedAxisException
    162     {
    163         return evaluate(contextNodes.get(0),
    164             StringFunction.evaluate(lang, nav), nav)
    165             ? Boolean.TRUE : Boolean.FALSE;
    166     }
    167
    168     private static boolean evaluate(Object node, String lang, Navigator nav)
    169       throws UnsupportedAxisException
    170     {
    171
    172         Object element = node;
    173         if (! nav.isElement(element)) {
    174             element = nav.getParentNode(node);
    175         }
    176         while (element != null && nav.isElement(element))
    177         {
    178             Iterator attrs = nav.getAttributeAxisIterator(element);
    179             while(attrs.hasNext())
    180             {
    181                 Object attr = attrs.next();
    182                 if(LANG_LOCALNAME.equals(nav.getAttributeName(attr)) &&
    183                    XMLNS_URI.equals(nav.getAttributeNamespaceUri(attr)))
    184                 {
    185                     return
    186                         isSublang(nav.getAttributeStringValue(attr), lang);
    187                 }
    188             }
    189             element = nav.getParentNode(element);
    190         }
    191         return false;
    192     }
    193
    194     private static boolean isSublang(String sublang, String lang)
    195     {
    196         if(sublang.equalsIgnoreCase(lang))
    197         {
    198             return true;
    199         }
    200         int ll = lang.length();
    201         return
    202             sublang.length() > ll &&
    203             sublang.charAt(ll) == '-' &&
    204             sublang.substring(0, ll).equalsIgnoreCase(lang);
    205     }
    206
    207 }
    208