/*
* $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/function/LangFunction.java,v 1.13 2006/02/05 21:47:41 elharo Exp $
* $Revision: 1.13 $
* $Date: 2006/02/05 21:47:41 $
*
* ====================================================================
*
* Copyright 2000-2002 bob mcwhirter & James Strachan.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* * Neither the name of the Jaxen Project nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
* OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* ====================================================================
* This software consists of voluntary contributions made by many
* individuals on behalf of the Jaxen Project and was originally
* created by bob mcwhirter <bob@werken.com> and
* James Strachan <jstrachan@apache.org>. For more information on the
* Jaxen Project, please see <http://www.jaxen.org/>.
*
* $Id: LangFunction.java,v 1.13 2006/02/05 21:47:41 elharo Exp $
*/
package org.orbeon.jaxen.function;
import org.orbeon.jaxen.*;
import java.util.Iterator;
import java.util.List;
/**
* <p>
* <b>4.3</b> <code><i>boolean</i> lang(<i>string</i>)</code>
* </p>
*
* <blockquote src="http://www.w3.org/TR/xpath#function-lang">
* <p>
* The <b>lang</b> function returns true or false depending on whether
* the language of the context node as specified by
* <code>xml:lang</code> attributes is the same as or is a sublanguage
* of the language specified by the argument string. The language of the
* context node is determined by the value of the <code>xml:lang</code>
*
* attribute on the context node, or, if the context node has no
* <code>xml:lang</code> attribute, by the value of the
* <code>xml:lang</code> attribute on the nearest ancestor of the
* context node that has an <code>xml:lang</code> attribute. If there
* is no such attribute, then <b><a href="#function-lang">lang</a></b>
* returns false. If there is such an attribute, then <b><a
* href="#function-lang">lang</a></b> returns true if the attribute
* value is equal to the argument ignoring case, or if there is some
* suffix starting with <code>-</code> such that the attribute value
* is equal to the argument ignoring that suffix of the attribute value
* and ignoring case. For example, <code>lang("en")</code> would
* return true if the context node is any of these five elements:
* </p>
*
* <pre>
* <para xml:lang="en"/>
* <div xml:lang="en"><para/></div>
* <para xml:lang="EN"/>
* <para xml:lang="en-us"/>
* </pre>
*
* </blockquote>
*
* @author Attila Szegedi (szegedia @ freemail.hu)
* @see <a href="http://www.w3.org/TR/xpath#function-lang"
* target="_top">XPath Specification</a>
*/
public class LangFunction implements Function
{
private static final String LANG_LOCALNAME = "lang";
private static final String XMLNS_URI =
"http://www.w3.org/XML/1998/namespace";
/**
* Create a new <code>LangFunction</code> object.
*/
public LangFunction() {}
/**
* <p>
* Determines whether or not the context node is written in the language specified
* by the XPath string-value of <code>args.get(0)</code>,
* as determined by the nearest <code>xml:lang</code> attribute in scope.
* </p>
*
* @param context the context in which to evaluate the <code>lang()</code> function
* @param args the arguments to the lang function
* @return a <code>Boolean</code> indicating whether the context node is written in
* the specified language
* @throws FunctionCallException if <code>args</code> does not have length one
*
*/
public Object call(Context context,
List args) throws FunctionCallException
{
if (args.size() != 1) {
throw new FunctionCallException("lang() requires exactly one argument.");
}
Object arg = args.get(0);
try {
return evaluate(context.getNodeSet(), arg, context.getNavigator() );
}
catch(UnsupportedAxisException e) {
throw new FunctionCallException("Can't evaluate lang()",
e);
}
}
private static Boolean evaluate(List contextNodes, Object lang, Navigator nav)
throws UnsupportedAxisException
{
return evaluate(contextNodes.get(0),
StringFunction.evaluate(lang, nav), nav)
? Boolean.TRUE : Boolean.FALSE;
}
private static boolean evaluate(Object node, String lang, Navigator nav)
throws UnsupportedAxisException
{
Object element = node;
if (! nav.isElement(element)) {
element = nav.getParentNode(node);
}
while (element != null && nav.isElement(element))
{
Iterator attrs = nav.getAttributeAxisIterator(element);
while(attrs.hasNext())
{
Object attr = attrs.next();
if(LANG_LOCALNAME.equals(nav.getAttributeName(attr)) &&
XMLNS_URI.equals(nav.getAttributeNamespaceUri(attr)))
{
return
isSublang(nav.getAttributeStringValue(attr), lang);
}
}
element = nav.getParentNode(element);
}
return false;
}
private static boolean isSublang(String sublang, String lang)
{
if(sublang.equalsIgnoreCase(lang))
{
return true;
}
int ll = lang.length();
return
sublang.length() > ll &&
sublang.charAt(ll) == '-' &&
sublang.substring(0, ll).equalsIgnoreCase(lang);
}
}