public void endElement(String namespaceURI, String localName, String rawName)
     throws SAXException {
   try {
     endElementIO(namespaceURI, localName, rawName);
   } catch (IOException except) {
     throw new SAXException(except);
   }
 }
  /**
   * Called to serialize a DOM element. Equivalent to calling {@link #startElement}, {@link
   * #endElement} and serializing everything inbetween, but better optimized.
   */
  protected void serializeElement(Element elem) throws IOException {
    Attr attr;
    NamedNodeMap attrMap;
    int i;
    Node child;
    ElementState state;
    String name;
    String value;
    String tagName;

    String prefix, localUri;
    String uri;
    if (fNamespaces) {
      // local binder stores namespace declaration
      // that has been printed out during namespace fixup of
      // the current element
      fLocalNSBinder.reset();

      // add new namespace context
      fNSBinder.pushContext();
    }

    if (DEBUG) {
      System.out.println(
          "==>startElement: " + elem.getNodeName() + " ns=" + elem.getNamespaceURI());
    }
    tagName = elem.getTagName();
    state = getElementState();
    if (isDocumentState()) {
      // If this is the root element handle it differently.
      // If the first root element in the document, serialize
      // the document's DOCTYPE. Space preserving defaults
      // to that of the output format.

      if (!_started) {
        startDocument(tagName);
      }
    } else {
      // For any other element, if first in parent, then
      // close parent's opening tag and use the parent's
      // space preserving.
      if (state.empty) _printer.printText('>');
      // Must leave CData section first
      if (state.inCData) {
        _printer.printText("]]>");
        state.inCData = false;
      }
      // Indent this element on a new line if the first
      // content of the parent element or immediately
      // following an element.
      if (_indenting
          && !state.preserveSpace
          && (state.empty || state.afterElement || state.afterComment)) _printer.breakLine();
    }

    // Do not change the current element state yet.
    // This only happens in endElement().
    fPreserveSpace = state.preserveSpace;

    int length = 0;
    attrMap = null;
    // retrieve attributes
    if (elem.hasAttributes()) {
      attrMap = elem.getAttributes();
      length = attrMap.getLength();
    }

    if (!fNamespaces) { // no namespace fixup should be performed

      // serialize element name
      _printer.printText('<');
      _printer.printText(tagName);
      _printer.indent();

      // For each attribute print it's name and value as one part,
      // separated with a space so the element can be broken on
      // multiple lines.
      for (i = 0; i < length; ++i) {
        attr = (Attr) attrMap.item(i);
        name = attr.getName();
        value = attr.getValue();
        if (value == null) value = "";
        printAttribute(name, value, attr.getSpecified(), attr);
      }
    } else { // do namespace fixup

      // REVISIT: some optimization could probably be done to avoid traversing
      //          attributes twice.
      //

      // ---------------------------------------
      // record all valid namespace declarations
      // before attempting to fix element's namespace
      // ---------------------------------------

      for (i = 0; i < length; i++) {

        attr = (Attr) attrMap.item(i);
        uri = attr.getNamespaceURI();
        // check if attribute is a namespace decl
        if (uri != null && uri.equals(NamespaceContext.XMLNS_URI)) {

          value = attr.getNodeValue();
          if (value == null) {
            value = XMLSymbols.EMPTY_STRING;
          }

          if (value.equals(NamespaceContext.XMLNS_URI)) {
            if (fDOMErrorHandler != null) {
              String msg =
                  DOMMessageFormatter.formatMessage(
                      DOMMessageFormatter.XML_DOMAIN, "CantBindXMLNS", null);
              modifyDOMError(msg, DOMError.SEVERITY_ERROR, null, attr);
              boolean continueProcess = fDOMErrorHandler.handleError(fDOMError);
              if (!continueProcess) {
                // stop the namespace fixup and validation
                throw new RuntimeException(
                    DOMMessageFormatter.formatMessage(
                        DOMMessageFormatter.SERIALIZER_DOMAIN, "SerializationStopped", null));
              }
            }
          } else {
            prefix = attr.getPrefix();
            prefix =
                (prefix == null || prefix.length() == 0)
                    ? XMLSymbols.EMPTY_STRING
                    : fSymbolTable.addSymbol(prefix);
            String localpart = fSymbolTable.addSymbol(attr.getLocalName());
            if (prefix == XMLSymbols.PREFIX_XMLNS) { // xmlns:prefix
              value = fSymbolTable.addSymbol(value);
              // record valid decl
              if (value.length() != 0) {
                fNSBinder.declarePrefix(localpart, value);
              } else {
                // REVISIT: issue error on invalid declarations
                //          xmlns:foo = ""
              }
              continue;
            } else { // xmlns
              // empty prefix is always bound ("" or some string)

              value = fSymbolTable.addSymbol(value);
              fNSBinder.declarePrefix(XMLSymbols.EMPTY_STRING, value);
              continue;
            }
          } // end-else: valid declaration
        } // end-if: namespace declaration
      } // end-for

      // -----------------------
      // get element uri/prefix
      // -----------------------
      uri = elem.getNamespaceURI();
      prefix = elem.getPrefix();

      // ----------------------
      // output element name
      // ----------------------
      // REVISIT: this could be removed if we always convert empty string to null
      //          for the namespaces.
      if ((uri != null && prefix != null) && uri.length() == 0 && prefix.length() != 0) {
        // uri is an empty string and element has some prefix
        // the namespace alg later will fix up the namespace attributes
        // remove element prefix
        prefix = null;
        _printer.printText('<');
        _printer.printText(elem.getLocalName());
        _printer.indent();
      } else {
        _printer.printText('<');
        _printer.printText(tagName);
        _printer.indent();
      }

      // ---------------------------------------------------------
      // Fix up namespaces for element: per DOM L3
      // Need to consider the following cases:
      //
      // case 1: <foo:elem xmlns:ns1="myURI" xmlns="default"/>
      // Assume "foo", "ns1" are declared on the parent. We should not miss
      // redeclaration for both "ns1" and default namespace. To solve this
      // we add a local binder that stores declaration only for current element.
      // This way we avoid outputing duplicate declarations for the same element
      // as well as we are not omitting redeclarations.
      //
      // case 2: <elem xmlns="" xmlns="default"/>
      // We need to bind default namespace to empty string, to be able to
      // omit duplicate declarations for the same element
      //
      // case 3: <xsl:stylesheet xmlns:xsl="http://xsl">
      // We create another element body bound to the "http://xsl" namespace
      // as well as namespace attribute rebounding xsl to another namespace.
      // <xsl:body xmlns:xsl="http://another">
      // Need to make sure that the new namespace decl value is changed to
      // "http://xsl"
      //
      // ---------------------------------------------------------
      // check if prefix/namespace is correct for current element
      // ---------------------------------------------------------

      if (uri != null) { // Element has a namespace
        uri = fSymbolTable.addSymbol(uri);
        prefix =
            (prefix == null || prefix.length() == 0)
                ? XMLSymbols.EMPTY_STRING
                : fSymbolTable.addSymbol(prefix);
        if (fNSBinder.getURI(prefix) == uri) {
          // The xmlns:prefix=namespace or xmlns="default" was declared at parent.
          // The binder always stores mapping of empty prefix to "".
          // (NOTE: local binder does not store this kind of binding!)
          // Thus the case where element was declared with uri="" (with or without a prefix)
          // will be covered here.

        } else {
          // the prefix is either undeclared
          // or
          // conflict: the prefix is bound to another URI
          if (fNamespacePrefixes) {
            printNamespaceAttr(prefix, uri);
          }
          fLocalNSBinder.declarePrefix(prefix, uri);
          fNSBinder.declarePrefix(prefix, uri);
        }
      } else { // Element has no namespace
        if (elem.getLocalName() == null) {
          //  DOM Level 1 node!
          if (fDOMErrorHandler != null) {
            String msg =
                DOMMessageFormatter.formatMessage(
                    DOMMessageFormatter.DOM_DOMAIN,
                    "NullLocalElementName",
                    new Object[] {elem.getNodeName()});
            modifyDOMError(msg, DOMError.SEVERITY_ERROR, null, elem);
            boolean continueProcess = fDOMErrorHandler.handleError(fDOMError);
            // REVISIT: should we terminate upon request?
            if (!continueProcess) {
              throw new RuntimeException(
                  DOMMessageFormatter.formatMessage(
                      DOMMessageFormatter.SERIALIZER_DOMAIN, "SerializationStopped", null));
            }
          }
        } else { // uri=null and no colon (DOM L2 node)
          uri = fNSBinder.getURI(XMLSymbols.EMPTY_STRING);

          if (uri != null && uri.length() > 0) {
            // there is a default namespace decl that is bound to
            // non-zero length uri, output xmlns=""
            if (fNamespacePrefixes) {
              printNamespaceAttr(XMLSymbols.EMPTY_STRING, XMLSymbols.EMPTY_STRING);
            }
            fLocalNSBinder.declarePrefix(XMLSymbols.EMPTY_STRING, XMLSymbols.EMPTY_STRING);
            fNSBinder.declarePrefix(XMLSymbols.EMPTY_STRING, XMLSymbols.EMPTY_STRING);
          }
        }
      }

      // -----------------------------------------
      // Fix up namespaces for attributes: per DOM L3
      // check if prefix/namespace is correct the attributes
      // -----------------------------------------

      for (i = 0; i < length; i++) {

        attr = (Attr) attrMap.item(i);
        value = attr.getValue();
        name = attr.getNodeName();

        uri = attr.getNamespaceURI();

        // Fix attribute that was declared with a prefix and namespace=""
        if (uri != null && uri.length() == 0) {
          uri = null;
          // we must remove prefix for this attribute
          name = attr.getLocalName();
        }

        if (DEBUG) {
          System.out.println("==>process attribute: " + attr.getNodeName());
        }
        // make sure that value is never null.
        if (value == null) {
          value = XMLSymbols.EMPTY_STRING;
        }

        if (uri != null) { // attribute has namespace !=null
          prefix = attr.getPrefix();
          prefix = prefix == null ? XMLSymbols.EMPTY_STRING : fSymbolTable.addSymbol(prefix);
          String localpart = fSymbolTable.addSymbol(attr.getLocalName());

          // ---------------------------------------------------
          // print namespace declarations namespace declarations
          // ---------------------------------------------------
          if (uri != null && uri.equals(NamespaceContext.XMLNS_URI)) {
            // check if we need to output this declaration
            prefix = attr.getPrefix();
            prefix =
                (prefix == null || prefix.length() == 0)
                    ? XMLSymbols.EMPTY_STRING
                    : fSymbolTable.addSymbol(prefix);
            localpart = fSymbolTable.addSymbol(attr.getLocalName());
            if (prefix == XMLSymbols.PREFIX_XMLNS) { // xmlns:prefix
              localUri = fLocalNSBinder.getURI(localpart); // local prefix mapping
              value = fSymbolTable.addSymbol(value);
              if (value.length() != 0) {
                if (localUri == null) {
                  // declaration was not printed while fixing element namespace binding

                  // If the DOM Level 3 namespace-prefixes feature is set to false
                  // do not print xmlns attributes
                  if (fNamespacePrefixes) {
                    printNamespaceAttr(localpart, value);
                  }

                  // case 4: <elem xmlns:xx="foo" xx:attr=""/>
                  // where attribute is bound to "bar".
                  // If the xmlns:xx is output here first, later we should not
                  // redeclare "xx" prefix. Instead we would pick up different prefix
                  // for the attribute.
                  // final: <elem xmlns:xx="foo" NS1:attr="" xmlns:NS1="bar"/>
                  fLocalNSBinder.declarePrefix(localpart, value);
                }
              } else {
                // REVISIT: issue error on invalid declarations
                //          xmlns:foo = ""
              }
              continue;
            } else { // xmlns
              // empty prefix is always bound ("" or some string)

              uri = fNSBinder.getURI(XMLSymbols.EMPTY_STRING);
              localUri = fLocalNSBinder.getURI(XMLSymbols.EMPTY_STRING);
              value = fSymbolTable.addSymbol(value);
              if (localUri == null) {
                // declaration was not printed while fixing element namespace binding
                if (fNamespacePrefixes) {
                  printNamespaceAttr(XMLSymbols.EMPTY_STRING, value);
                }
                // case 4 does not apply here since attributes can't use
                // default namespace
              }
              continue;
            }
          }
          uri = fSymbolTable.addSymbol(uri);

          // find if for this prefix a URI was already declared
          String declaredURI = fNSBinder.getURI(prefix);

          if (prefix == XMLSymbols.EMPTY_STRING || declaredURI != uri) {
            // attribute has no prefix (default namespace decl does not apply to attributes)
            // OR
            // attribute prefix is not declared
            // OR
            // conflict: attr URI does not match the prefix in scope

            name = attr.getNodeName();
            // Find if any prefix for attributes namespace URI is available
            // in the scope
            String declaredPrefix = fNSBinder.getPrefix(uri);

            if (declaredPrefix != null && declaredPrefix != XMLSymbols.EMPTY_STRING) {
              // use the prefix that was found
              prefix = declaredPrefix;
              name = prefix + ":" + localpart;
            } else {
              if (DEBUG) {
                System.out.println("==> cound not find prefix for the attribute: " + prefix);
              }

              if (prefix != XMLSymbols.EMPTY_STRING && fLocalNSBinder.getURI(prefix) == null) {
                // the current prefix is not null and it has no in scope declaration

                // use this prefix
              } else {
                // find a prefix following the pattern "NS" +index (starting at 1)
                // make sure this prefix is not declared in the current scope.
                int counter = 1;
                prefix = fSymbolTable.addSymbol(PREFIX + counter++);
                while (fLocalNSBinder.getURI(prefix) != null) {
                  prefix = fSymbolTable.addSymbol(PREFIX + counter++);
                }
                name = prefix + ":" + localpart;
              }
              // add declaration for the new prefix
              if (fNamespacePrefixes) {
                printNamespaceAttr(prefix, uri);
              }
              value = fSymbolTable.addSymbol(value);
              fLocalNSBinder.declarePrefix(prefix, value);
              fNSBinder.declarePrefix(prefix, uri);
            }

            // change prefix for this attribute
          }

          printAttribute(
              name, (value == null) ? XMLSymbols.EMPTY_STRING : value, attr.getSpecified(), attr);
        } else { // attribute uri == null
          if (attr.getLocalName() == null) {
            if (fDOMErrorHandler != null) {
              String msg =
                  DOMMessageFormatter.formatMessage(
                      DOMMessageFormatter.DOM_DOMAIN,
                      "NullLocalAttrName",
                      new Object[] {attr.getNodeName()});
              modifyDOMError(msg, DOMError.SEVERITY_ERROR, null, attr);
              boolean continueProcess = fDOMErrorHandler.handleError(fDOMError);
              if (!continueProcess) {
                // stop the namespace fixup and validation
                throw new RuntimeException(
                    DOMMessageFormatter.formatMessage(
                        DOMMessageFormatter.SERIALIZER_DOMAIN, "SerializationStopped", null));
              }
            }
            printAttribute(name, value, attr.getSpecified(), attr);
          } else { // uri=null and no colon

            // no fix up is needed: default namespace decl does not
            // apply to attributes
            printAttribute(name, value, attr.getSpecified(), attr);
          }
        }
      } // end loop for attributes
    } // end namespace fixup algorithm

    // If element has children, then serialize them, otherwise
    // serialize en empty tag.
    if (elem.hasChildNodes()) {
      // Enter an element state, and serialize the children
      // one by one. Finally, end the element.
      state = enterElementState(null, null, tagName, fPreserveSpace);
      state.doCData = _format.isCDataElement(tagName);
      state.unescaped = _format.isNonEscapingElement(tagName);
      child = elem.getFirstChild();
      while (child != null) {
        serializeNode(child);
        child = child.getNextSibling();
      }
      if (fNamespaces) {
        fNSBinder.popContext();
      }
      endElementIO(null, null, tagName);
    } else {
      if (DEBUG) {
        System.out.println("==>endElement: " + elem.getNodeName());
      }
      if (fNamespaces) {
        fNSBinder.popContext();
      }
      _printer.unindent();
      _printer.printText("/>");
      // After element but parent element is no longer empty.
      state.afterElement = true;
      state.afterComment = false;
      state.empty = false;
      if (isDocumentState()) _printer.flush();
    }
  }