code: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements. See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership. The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the  "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  /*
   * $Id$
   */
  package org.apache.xpath.functions;
  
  import org.apache.xml.dtm.DTM;
  import org.apache.xpath.XPathContext;
  import org.apache.xpath.objects.XBoolean;
  import org.apache.xpath.objects.XObject;
  
  /**
   * Execute the Lang() function.
   * @xsl.usage advanced
   */
  public class FuncLang extends FunctionOneArg
  {
      static final long serialVersionUID = -7868705139354872185L;
  
    /**
     * Execute the function.  The function must return
     * a valid object.
     * @param xctxt The current execution context.
     * @return A valid XObject.
     *
     * @throws javax.xml.transform.TransformerException
     */
    public XObject execute(XPathContext xctxt) throws javax.xml.transform.TransformerException
    {
  
      String lang = m_arg0.execute(xctxt).str();
      int parent = xctxt.getCurrentNode();
      boolean isLang = false;
      DTM dtm = xctxt.getDTM(parent);
  
      while (DTM.NULL != parent)
      {
        if (DTM.ELEMENT_NODE == dtm.getNodeType(parent))
        {
          int langAttr = dtm.getAttributeNode(parent, "http://www.w3.org/XML/1998/namespace", "lang");
  
          if (DTM.NULL != langAttr)
          {
            String langVal = dtm.getNodeValue(langAttr);
            // %OPT%
            if (langVal.toLowerCase().startsWith(lang.toLowerCase()))
            {
              int valLen = lang.length();
  
              if ((langVal.length() == valLen)
                      || (langVal.charAt(valLen) == '-'))
              {
                isLang = true;
              }
            }
  
            break;
          }
        }
  
        parent = dtm.getParent(parent);
      }
  
      return isLang ? XBoolean.S_TRUE : XBoolean.S_FALSE;
    }
  }
  