/*
 * 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.XObject;
import org.apache.xpath.objects.XString;

/**
 * Execute the Namespace() function.
 * @xsl.usage advanced
 */
public class FuncNamespace extends FunctionDef1Arg
{
    static final long serialVersionUID = -4695674566722321237L;

  /**
   * 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
  {

    int context = getArg0AsNode(xctxt);
    
    String s;
    if(context != DTM.NULL)
    {
      DTM dtm = xctxt.getDTM(context);
      int t = dtm.getNodeType(context);
      if(t == DTM.ELEMENT_NODE)
      {
        s = dtm.getNamespaceURI(context);
      }
      else if(t == DTM.ATTRIBUTE_NODE)
      {

        // This function always returns an empty string for namespace nodes.
        // We check for those here.  Fix inspired by Davanum Srinivas.

        s = dtm.getNodeName(context);
        if(s.startsWith("xmlns:") || s.equals("xmlns"))
          return XString.EMPTYSTRING;

        s = dtm.getNamespaceURI(context);
      }
      else
        return XString.EMPTYSTRING;
    }
    else 
      return XString.EMPTYSTRING;
    
    return ((null == s) ? XString.EMPTYSTRING : new XString(s));
  }
}