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.xalan.templates.Constants;
  import org.apache.xalan.transformer.TransformerImpl;
  import org.apache.xml.utils.QName;
  import org.apache.xpath.ExtensionsProvider;
  import org.apache.xpath.XPathContext;
  import org.apache.xpath.objects.XBoolean;
  import org.apache.xpath.objects.XObject;
  
  /**
   * Execute the ExtElementAvailable() function.
   * @xsl.usage advanced
   */
  public class FuncExtElementAvailable extends FunctionOneArg
  {
      static final long serialVersionUID = -472533699257968546L;
  
    /**
     * 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 prefix;
      String namespace;
      String methName;
  
      String fullName = m_arg0.execute(xctxt).str();
      int indexOfNSSep = fullName.indexOf(':');
  
      if (indexOfNSSep < 0)
      {
        prefix = "";
        namespace = Constants.S_XSLNAMESPACEURL;
        methName = fullName;
      }
      else
      {
        prefix = fullName.substring(0, indexOfNSSep);
        namespace = xctxt.getNamespaceContext().getNamespaceForPrefix(prefix);
        if (null == namespace)
          return XBoolean.S_FALSE;
        methName= fullName.substring(indexOfNSSep + 1);
      }
  
      if (namespace.equals(Constants.S_XSLNAMESPACEURL)
      ||  namespace.equals(Constants.S_BUILTIN_EXTENSIONS_URL))
      {
        try
        {
          TransformerImpl transformer = (TransformerImpl) xctxt.getOwnerObject();
          return transformer.getStylesheet().getAvailableElements().containsKey(
                                                              new QName(namespace, methName))
                 ? XBoolean.S_TRUE : XBoolean.S_FALSE;
        }
        catch (Exception e)
        {
          return XBoolean.S_FALSE;
        }
      }
      else
      {
        //dml
        ExtensionsProvider extProvider = (ExtensionsProvider)xctxt.getOwnerObject();
        return extProvider.elementAvailable(namespace, methName)
               ? XBoolean.S_TRUE : XBoolean.S_FALSE;
      }
    }
  }
  