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.xalan.xsltc.trax;
  
  import javax.xml.transform.Source;
  import javax.xml.transform.stream.StreamSource;
  
  import org.apache.xalan.xsltc.DOM;
  import org.apache.xalan.xsltc.StripFilter;
  import org.apache.xalan.xsltc.compiler.util.ErrorMsg;
  import org.apache.xalan.xsltc.dom.DOMWSFilter;
  import org.apache.xalan.xsltc.dom.SAXImpl;
  import org.apache.xalan.xsltc.dom.XSLTCDTMManager;
  import org.apache.xalan.xsltc.runtime.AbstractTranslet;
  
  import org.xml.sax.SAXException;
  
  /**
   * @author Morten Jorgensen
   */
  public final class XSLTCSource implements Source {
  
      private String     _systemId = null;
      private Source     _source   = null;
      private ThreadLocal _dom     = new ThreadLocal();
  
      /**
       * Create a new XSLTC-specific source from a system ID 
       */
      public XSLTCSource(String systemId) 
      {
          _systemId = systemId;
      }
  
      /**
       * Create a new XSLTC-specific source from a JAXP Source
       */
      public XSLTCSource(Source source) 
      {
          _source = source;
      }
  
      /**
       * Implements javax.xml.transform.Source.setSystemId()
       * Set the system identifier for this Source. 
       * This Source can get its input either directly from a file (in this case
       * it will instanciate and use a JAXP parser) or it can receive it through
       * ContentHandler/LexicalHandler interfaces.
       * @param systemId The system Id for this Source
       */
      public void setSystemId(String systemId) {
          _systemId = systemId;
          if (_source != null) {
              _source.setSystemId(systemId);
          }
      }
  
      /**
       * Implements javax.xml.transform.Source.getSystemId()
       * Get the system identifier that was set with setSystemId.
       * @return The system identifier that was set with setSystemId,
       *         or null if setSystemId was not called.
       */
      public String getSystemId() {
  	if (_source != null) {
  	    return _source.getSystemId();
  	}
  	else {
  	    return(_systemId);
  	}
      }
      
      /**
       * Internal interface which returns a DOM for a given DTMManager and translet.
       */
      protected DOM getDOM(XSLTCDTMManager dtmManager, AbstractTranslet translet)
          throws SAXException
      {
          SAXImpl idom = (SAXImpl)_dom.get();
                  
          if (idom != null) {
              if (dtmManager != null) {
                  idom.migrateTo(dtmManager);
              }
          }
          else {
              Source source = _source;
              if (source == null) {
                  if (_systemId != null && _systemId.length() > 0) {
                      source = new StreamSource(_systemId);
                  }
                  else {
                      ErrorMsg err = new ErrorMsg(ErrorMsg.XSLTC_SOURCE_ERR);
                      throw new SAXException(err.toString());
                  }
              }
              
              DOMWSFilter wsfilter = null;
              if (translet != null && translet instanceof StripFilter) {
                  wsfilter = new DOMWSFilter(translet);
              }
                  
              boolean hasIdCall = (translet != null) ? translet.hasIdCall() : false;
              
              if (dtmManager == null) {
                  dtmManager = XSLTCDTMManager.newInstance();
              }
              
              idom = (SAXImpl)dtmManager.getDTM(source, true, wsfilter, false, false, hasIdCall);
              
              String systemId = getSystemId();
              if (systemId != null) {
                  idom.setDocumentURI(systemId);
              }
              _dom.set(idom);
          }
          return idom;
      }
  
  }
  