package edu.stanford.db.xml.util;import org.w3c.rdf.syntax.*;import org.xml.sax.*;import org.xml.sax.helpers.*;import java.util.*;import java.io.*;import java.net.*;import java.lang.ref.WeakReference;public class GenericParser extends DefaultHandler { /*EntityResolver, DTDHandler, DocumentHandler, */  protected ErrorHandler errorHandler = null;  protected Locator locator = new LocatorImpl();  protected InputSource source;  protected Element current;  // collect all namespaces here  protected Hashtable namespaces = new Hashtable();  static final String DEFAULT_PARSER = "org.brownell.xml.aelfred2.SAXDriver";  protected String parserClass = null;  protected int numInParent = 0;  public GenericParser () {    this(true);  }  public GenericParser (boolean warn) {    initXMLParser(warn);  }  // override EntityResolver implementation  public InputSource resolveEntity(String publicId, String systemId) throws SAXException {    System.err.println("[Warning] ignoring external entity " + systemId);    return new InputSource(new CharArrayReader(new char[0]));  }  // @since 2000-10-31  // optimization for string generation  protected static WeakHashMap atoms = new WeakHashMap();  public static QName createQName(String ns, String ln) {    return new QName(create(ns), create(ln));  }  public static String create(String s) {    if(s == null)      return null;    WeakReference ref = (WeakReference)atoms.get(s);    if(ref == null)      atoms.put(s, new WeakReference(s));    else {      Object o = ref.get();      if(o == null) { // just trashed by GC	atoms.put(s, new WeakReference(s));      } else	s = (String)o;    }    return s;  }  protected void initXMLParser(boolean warn) {    try {      if((parserClass = System.getProperty("org.xml.sax.parser")) == null) {	if(warn) {	  System.err.println("Warning: using the default XML parser (" + getDefaultParserClass() + ").\n" +			     "Override for IBM xml4j is: -Dorg.xml.sax.parser=com.ibm.xml.parser.SAXDriver");	  //	  System.getProperties().put("org.xml.sax.parser", getDefaultParserClass());	}      } else // parser has been explicitly overridden	return;    } catch (SecurityException any) {      // I'm an applet      if(warn)	System.err.println("Warning: could not access system properties, using default XML parser (" + getDefaultParserClass() + ").");    }    parserClass = getDefaultParserClass();    //    new Exception().printStackTrace(System.err);  }  protected String getDefaultParserClass() {        return DEFAULT_PARSER;  }  protected String getParserClass() {    return parserClass;  }  protected XMLReader createXMLReader() {    //      XMLReader p = XMLReaderFactory.createXMLReader();    return createXMLReader(getParserClass());  }  /**   * Generate a warning message as a string   */    public void addWarning (String sMsg) throws SAXException {      errorHandler.warning(new SAXParseException(sMsg, locator));    }    /**   * Generate an error message as a string   */   public void addError (String sMsg) throws SAXException {     errorHandler.error(new SAXParseException(sMsg, locator));   }  //   public void setDocumentLocator (Locator locator) {//     this.locator = locator;//   }    public void setErrorHandler (ErrorHandler handler) {    this.errorHandler = handler;  }  protected String getSourceURI() {    return source.getSystemId();  }  public void startElement (String uri, String name, String qName, Attributes atts) throws SAXException {    _startElement(uri, name, atts);    System.out.println("Start element: " + current.getName());  }  public Enumeration getNamespaces() {    return namespaces.keys();  }  protected void addNamespace(String uri) {    if(!"".equals(uri))      namespaces.put(uri, uri);  }  protected void _startElement (String uri, String name, Attributes al) throws SAXException {    Element el = createElement();    el.setName(new QName(uri, name));    el.setNumInParent(numInParent);    numInParent = 1;    addNamespace(uri);    // add attributes    for (int x = 0; x < al.getLength(); x++) {      String aURI = al.getURI(x);      addNamespace(aURI);      // take element's namespace if none specified      // FIXED: this was not XML-NS compliant!//       if("".equals(aURI))// 	aURI = uri;      QName aName = new QName(aURI, al.getLocalName(x));      String aValue = al.getValue (x);      //      System.out.println("Adding property: " + aName + "=" + aValue);      el.setAttribute(aName, aValue);    }    if(current == null)      current = el;    else {      current.setChild(el);      el.setParent(current);      current = el;    }  }  protected Element createElement() {    return new Element();  }  public void endElement (String uri, String name, String qName) throws SAXException {    System.out.println("End element: " + current.getName());    _endElement(uri, name);  }  protected void _endElement (String uri, String name) throws SAXException {    numInParent = current.getNumInParent() + 1;    current = current.getParent();  }  protected boolean preserveWhiteSpace() {    return false;  }  public void characters (char ch[], int start, int length)    throws SAXException {        String s = new String (ch, start, length);      String sTrimmed = s.trim();      if (sTrimmed.length() > 0 || preserveWhiteSpace()) {	// System.out.println("Adding characters: \"" + s + "\"");	current.setValue(sTrimmed);      }  }  public static XMLReader createXMLReader(String className) {    try {      // Get the named class.      Class c = Class.forName(className);      // Instantiate the parser.      return (XMLReader)(c.newInstance());    } catch (Exception any) {      throw new RuntimeException("Could not instantiate XML parser: " + any);    }  }      public static InputSource getInputSource(String urlStr) throws MalformedURLException, IOException {    InputStream in = null;    URL url = null;    if(urlStr != null) {      try {	url = new URL (urlStr);      } catch (Exception e) {	url = new URL ("file", null, urlStr);      }      in = url.openStream();          } else {      // read from stdin      in = System.in;    }        Reader r = new BufferedReader(new InputStreamReader(in));    InputSource source = new InputSource(r);    if(urlStr != null)      source.setSystemId(url.toString());    return source;  }}