OdfFileDom.java

/**
 * **********************************************************************
 *
 * <p>DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
 *
 * <p>Copyright 2008, 2010 Oracle and/or its affiliates. All rights reserved.
 *
 * <p>Use is subject to license terms.
 *
 * <p>Licensed 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. You can also obtain a copy of the License at
 * http://odftoolkit.org/docs/license.txt
 *
 * <p>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.
 *
 * <p>See the License for the specific language governing permissions and limitations under the
 * License.
 *
 * <p>**********************************************************************
 */
package org.odftoolkit.odfdom.pkg;

import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Field;
import java.util.HashMap;
import java.util.HashSet;
import java.util.IdentityHashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.xml.XMLConstants;
import javax.xml.namespace.NamespaceContext;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathFactory;
import org.apache.jena.rdf.model.Model;
import org.apache.xerces.dom.DocumentImpl;
import org.odftoolkit.odfdom.dom.OdfContentDom;
import org.odftoolkit.odfdom.dom.OdfMetaDom;
import org.odftoolkit.odfdom.dom.OdfSchemaDocument;
import org.odftoolkit.odfdom.dom.OdfSettingsDom;
import org.odftoolkit.odfdom.dom.OdfStylesDom;
import org.odftoolkit.odfdom.dom.rdfa.BookmarkRDFMetadataExtractor;
import org.odftoolkit.odfdom.pkg.manifest.OdfManifestDom;
import org.odftoolkit.odfdom.pkg.rdfa.DOMRDFaParser;
import org.odftoolkit.odfdom.pkg.rdfa.JenaSink;
import org.odftoolkit.odfdom.pkg.rdfa.MultiContentHandler;
import org.odftoolkit.odfdom.pkg.rdfa.SAXRDFaParser;
import org.odftoolkit.odfdom.pkg.rdfa.Util;
import org.w3c.dom.DOMException;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.DefaultHandler;

/** The DOM representation of an XML file within the ODF document. */
public class OdfFileDom extends DocumentImpl implements NamespaceContext {

  private static final long serialVersionUID = 766167617530147000L;
  protected String mPackagePath;
  protected OdfPackageDocument mPackageDocument;
  protected OdfPackage mPackage;
  protected XPath mXPath;
  protected Map<String, String> mUriByPrefix;
  protected Map<String, String> mPrefixByUri;
  /** Contains only the duplicate prefix. The primary hold by mPrefixByUri still have to be added */
  protected Map<String, Set<String>> mDuplicatePrefixesByUri;
  /**
   * The cache of in content metadata: key: a Node in the dom ; value: the Jena RDF model of triples
   * of the Node
   */
  protected Map<Node, Model> inCententMetadataCache;

  protected JenaSink sink;

  /**
   * Creates the DOM representation of an XML file of an ODF document.
   *
   * @param packageDocument the document the XML files belongs to
   * @param packagePath the internal package path to the XML file
   */
  protected OdfFileDom(OdfPackageDocument packageDocument, String packagePath) {
    super(false);
    if (packageDocument != null && packagePath != null) {
      mPackageDocument = packageDocument;
      mPackage = packageDocument.getPackage();
      mPackagePath = packagePath;
      mUriByPrefix = new HashMap<String, String>();
      mPrefixByUri = new HashMap<String, String>();
      mDuplicatePrefixesByUri = new HashMap<String, Set<String>>();
      inCententMetadataCache = new IdentityHashMap<Node, Model>();
      try {
        initialize();
      } catch (SAXException | IOException | ParserConfigurationException ex) {
        Logger.getLogger(OdfFileDom.class.getName()).log(Level.SEVERE, null, ex);
      }
      // Register every DOM to OdfPackage,
      // so a package close might save this DOM (similar as OdfDocumentPackage)
      this.addDomToCache(mPackage, packagePath);
    } else {
      throw new IllegalArgumentException(
          "Arguments are not allowed to be NULL for OdfFileDom constructor!");
    }
  }

  /**
   * Creates the DOM representation of an XML file of an Odf document.
   *
   * @param pkg the package the XML files belongs to
   * @param packagePath the internal package path to the XML file
   */
  protected OdfFileDom(OdfPackage pkg, String packagePath) {
    super(false);
    if (pkg != null && packagePath != null) {
      mPackageDocument = null;
      mPackage = pkg;
      mPackagePath = packagePath;
      mUriByPrefix = new HashMap<String, String>();
      mPrefixByUri = new HashMap<String, String>();
      mDuplicatePrefixesByUri = new HashMap<String, Set<String>>();
      inCententMetadataCache = new HashMap<Node, Model>();
      try {
        initialize();
      } catch (SAXException | IOException | ParserConfigurationException ex) {
        Logger.getLogger(OdfFileDom.class.getName()).log(Level.SEVERE, null, ex);
      }
      // Register every DOM to OdfPackage,
      // so a package close might save this DOM (similar as
      // OdfDocumentPackage)
      addDomToCache(mPackage, packagePath);
    } else {
      throw new IllegalArgumentException(
          "Arguments are not allowed to be NULL for OdfFileDom constructor!");
    }
  }

  /**
   * Adds the document to the pool of open documents of the package. A document of a certain path is
   * opened only once to avoid data duplication.
   */
  private void addDomToCache(OdfPackage pkg, String internalPath) {
    pkg.cacheDom(this, internalPath);
  }

  static OdfFileDom newFileDom(OdfPackageDocument packageDocument, String packagePath) {
    OdfFileDom newFileDom = null;
    // before creating a new dom, make sure that there no DOM opened for this file already
    Document existingDom = packageDocument.getPackage().getCachedDom(packagePath);
    if (existingDom == null) {
      // ToDo: bug 264 - register OdfFileDom to this class
      if (packagePath.equals("content.xml") || packagePath.endsWith("/content.xml")) {
        newFileDom = new OdfContentDom((OdfSchemaDocument) packageDocument, packagePath);
      } else if (packagePath.equals("styles.xml") || packagePath.endsWith("/styles.xml")) {
        newFileDom = new OdfStylesDom((OdfSchemaDocument) packageDocument, packagePath);
      } else if (packagePath.equals("meta.xml") || packagePath.endsWith("/meta.xml")) {
        newFileDom = new OdfMetaDom((OdfSchemaDocument) packageDocument, packagePath);
      } else if (packagePath.equals("settings.xml") || packagePath.endsWith("/settings.xml")) {
        newFileDom = new OdfSettingsDom((OdfSchemaDocument) packageDocument, packagePath);
      } else if (packagePath.equals("META-INF/manifest.xml")
          || packagePath.endsWith("/META-INF/manifest.xml")) {
        newFileDom = new OdfManifestDom((OdfSchemaDocument) packageDocument, packagePath);
      } else {
        newFileDom = new OdfFileDom(packageDocument, packagePath);
      }
    } else {
      if (existingDom instanceof OdfFileDom) {
        newFileDom = (OdfFileDom) existingDom;
        // ToDO: Issue 264 - Otherwise if NOT an OdfFileDom serialize old DOM AND CREATE A NEW ONE?!
        // Or shall we always reference to the dom, than we can not inherit from Document? Pro/Con?s
        //			}else{
        //				// Create an OdfFileDOM from an existing DOM
        //				newFileDom =
      }
    }
    return newFileDom;
  }

  public static OdfFileDom newFileDom(OdfPackage pkg, String packagePath) {
    OdfFileDom newFileDom = null;
    // before creating a new dom, make sure that there no DOM opened for this file already
    Document existingDom = pkg.getCachedDom(packagePath);
    if (existingDom == null) {
      if (packagePath.equals("META-INF/manifest.xml")
          || packagePath.endsWith("/META-INF/manifest.xml")) {
        newFileDom = new OdfManifestDom(pkg, packagePath);
      } else {
        newFileDom = new OdfFileDom(pkg, packagePath);
      }
    } else {
      if (existingDom instanceof OdfFileDom) {
        newFileDom = (OdfFileDom) existingDom;
        // ToDO: Issue 264 - Otherwise if NOT an OdfFileDom serialize old DOM AND CREATE A NEW ONE?!
        // Or shall we always reference to the dom, than we can not inherit from Document? Pro/Con?s
        //			}else{
        //				// Create an OdfFileDOM from an existing DOM
        //				newFileDom =
      }
    }
    return newFileDom;
  }

  protected void initialize() throws SAXException, IOException, ParserConfigurationException {
    initialize(new OdfFileSaxHandler(this), this);
  }

  protected void initialize(DefaultHandler handler, OdfFileDom dom)
      throws SAXException, IOException, ParserConfigurationException {
    InputStream fileStream = null;
    try {
      fileStream = mPackage.getInputStream(mPackagePath);
      if (fileStream != null) {
        XMLReader xmlReader = mPackage.getXMLReader();
        String baseUri = Util.getRDFBaseUri(mPackage.getBaseURI(), mPackagePath);
        if (handler instanceof OdfFileSaxHandler) {
          OdfFileSaxHandler odfSaxHandler = ((OdfFileSaxHandler) handler);
          sink = new JenaSink(this);
          odfSaxHandler.setSink(sink);
          SAXRDFaParser rdfa = SAXRDFaParser.createInstance(sink);
          rdfa.setBase(baseUri);
          // the file is parsed by ODF ContentHandler, and then RDFa ContentHandler
          MultiContentHandler multi = new MultiContentHandler(odfSaxHandler, rdfa);
          xmlReader.setContentHandler(multi);
        } else {
          xmlReader.setContentHandler(handler);
        }
        InputSource xmlSource = new InputSource(fileStream);
        xmlReader.parse(xmlSource);
      }
    } catch (IOException | ParserConfigurationException | SAXException ex) {
      Logger.getLogger(OdfFileDom.class.getName()).log(Level.SEVERE, null, ex);
      throw ex;
    } finally {
      try {
        if (fileStream != null) {
          fileStream.close();
        }
      } catch (IOException iex) {
        Logger.getLogger(OdfFileDom.class.getName()).log(Level.SEVERE, null, iex);
      }
    }
  }

  /**
   * Retrieves the <code>OdfPackageDocument</code> of the XML file. A package document is usually
   * represented as a directory with a media type.
   *
   * @return The document holding the XML file.
   */
  public OdfPackageDocument getDocument() {
    return mPackageDocument;
  }

  /**
   * Retrieves the <code>String</code> of Package Path
   *
   * @return The path of the XML file relative to the package root
   */
  public String getPackagePath() {
    return mPackagePath;
  }

  /**
   * Retrieves the ODF root element.
   *
   * @return The <code>OdfElement</code> being the root of the document.
   */
  public OdfElement getRootElement() {
    return (OdfElement) getDocumentElement();
  }

  /**
   * Create ODF element with namespace uri and qname
   *
   * @param name The element name
   */
  @Override
  public OdfElement createElement(String name) throws DOMException {
    return createElementNS(OdfName.newName(name));
  }

  /**
   * Create ODF element with namespace uri and qname
   *
   * @param nsuri The namespace uri
   * @param qname The element qname
   */
  @Override
  public OdfElement createElementNS(String nsuri, String qname) throws DOMException {
    return createElementNS(OdfName.newName(nsuri, qname));
  }

  /**
   * Create ODF element with ODF name
   *
   * @param name The <code>OdfName</code>
   * @return The <code>OdfElement</code>
   * @throws DOMException
   */
  public OdfElement createElementNS(OdfName name) throws DOMException {
    return OdfXMLFactory.newOdfElement(this, name);
  }

  /**
   * Create the ODF attribute with its name
   *
   * @param name the attribute qname
   * @return The <code>OdfAttribute</code>
   * @throws DOMException
   */
  @Override
  public OdfAttribute createAttribute(String name) throws DOMException {
    return createAttributeNS(OdfName.newName(name));
  }

  /**
   * Create the ODF attribute with namespace uri and qname
   *
   * @param nsuri The namespace uri
   * @param qname the attribute qname
   * @return The <code>OdfAttribute</code>
   * @throws DOMException
   */
  @Override
  public OdfAttribute createAttributeNS(String nsuri, String qname) throws DOMException {
    return createAttributeNS(OdfName.newName(nsuri, qname));
  }

  /**
   * Create the ODF attribute with ODF name
   *
   * @param name The <code>OdfName</code>
   * @return The <code>OdfAttribute</code>
   * @throws DOMException
   */
  public OdfAttribute createAttributeNS(OdfName name) throws DOMException {
    return OdfXMLFactory.newOdfAttribute(this, name);
  }

  @SuppressWarnings("unchecked")
  /**
   * @return an ODF element of the given subclass, defined by its ELEMENT_NAME field. Returns null
   *     for none ODF elements, as they are of type OdfAlienElement without such field, as their XML
   *     name varies.
   */
  public <T extends OdfElement> T newOdfElement(Class<T> clazz) {
    //        return (T) OdfXMLFactory.getNodeFromClass(this, clazz);
    try {
      Field fname = clazz.getField("ELEMENT_NAME");
      OdfName name = (OdfName) fname.get(null);
      return (T) createElementNS(name);
    } catch (Exception ex) {
      if (ex instanceof RuntimeException) {
        throw (RuntimeException) ex;
      }
      return null;
    }
  }

  @Override
  public String toString() {
    return ((OdfElement) this.getDocumentElement()).toString();
  }

  // JDK Namespace handling
  /**
   * Create an XPath instance to select one or more nodes from an ODF document. Therefore the
   * namespace context is set to the OdfNamespace
   *
   * @return an XPath instance with namespace context set to include the standard ODFDOM prefixes.
   */
  public XPath getXPath() {
    if (mXPath == null) {
      mXPath = XPathFactory.newInstance().newXPath();
    }
    return mXPath;
  }

  /**
   * Get Namespace URI bound to a prefix in the current scope (the XML file).
   *
   * <p>When requesting a Namespace URI by prefix, the following table describes the returned
   * Namespace URI value for all possible prefix values:
   *
   * <table border="2" rules="all" cellpadding="4">
   * <thead>
   * <tr>
   * <td align="center" colspan="2">
   * <code>getNamespaceURI(prefix)</code> return value for specified prefixes
   * </td>
   * </tr>
   * <tr>
   * <td>prefix parameter</td>
   * <td>Namespace URI return value</td>
   * </tr>
   * </thead>
   * <tbody>
   * <tr>
   * <td><code>DEFAULT_NS_PREFIX</code> ("")</td>
   * <td>default Namespace URI in the current scope or      <code>{@link
   *         javax.xml.XMLConstants#NULL_NS_URI XMLConstants.NULL_NS_URI("")}
   * </code> when there is no default Namespace URI in the current scope</td>
   * </tr>
   * <tr>
   * <td>bound prefix</td>
   * <td>Namespace URI bound to prefix in current scope</td>
   * </tr>
   * <tr>
   * <td>unbound prefix</td>
   * <td>
   * <code>{@link
   *         javax.xml.XMLConstants#NULL_NS_URI XMLConstants.NULL_NS_URI("")}
   * </code>
   * </td>
   * </tr>
   * <tr>
   * <td><code>XMLConstants.XML_NS_PREFIX</code> ("xml")</td>
   * <td><code>XMLConstants.XML_NS_URI</code>
   * ("http://www.w3.org/XML/1998/namespace")</td>
   * </tr>
   * <tr>
   * <td><code>XMLConstants.XMLNS_ATTRIBUTE</code> ("xmlns")</td>
   * <td><code>XMLConstants.XMLNS_ATTRIBUTE_NS_URI</code>
   * ("http://www.w3.org/2000/xmlns/")</td>
   * </tr>
   * <tr>
   * <td><code>null</code></td>
   * <td><code>IllegalArgumentException</code> is thrown</td>
   * </tr>
   * </tbody>
   * </table>
   *
   * @param prefix prefix to look up
   * @return Namespace URI bound to prefix in the current scope
   * @throws IllegalArgumentException When <code>prefix</code> is <code>null</code>
   */
  public String getNamespaceURI(String prefix) {
    String nsURI = null;
    nsURI = mUriByPrefix.get(prefix);
    if (nsURI == null) {
      // look in Duplicate URI prefixes
      Set<String> urisWithDuplicatePrefixes = this.mDuplicatePrefixesByUri.keySet();
      for (String aURI : urisWithDuplicatePrefixes) {
        Set<String> prefixes = this.mDuplicatePrefixesByUri.get(aURI);
        // check if requested prefix exists in hashset
        if (prefixes.contains(prefix)) {
          nsURI = aURI;
          break;
        }
      }
    }
    // there is a possibility it still may be null - so we check
    if (nsURI == null) {
      nsURI = XMLConstants.NULL_NS_URI;
    }
    return nsURI;
  }

  /**
   * Get prefix bound to Namespace URI in the current scope (the XML file).
   *
   * <p>Multiple prefixes bound to Namespace URI will be normalized to the first prefix defined.
   *
   * <p>When requesting a prefix by Namespace URI, the following table describes the returned prefix
   * value for all Namespace URI values:
   *
   * <table border="2" rules="all" cellpadding="4">
   * <thead>
   * <tr>
   * <th align="center" colspan="2">
   * <code>getPrefix(namespaceURI)</code> return value for specified Namespace
   * URIs
   * </th>
   * </tr>
   * <tr>
   * <th>Namespace URI parameter</th>
   * <th>prefix value returned</th>
   * </tr>
   * </thead>
   * <tbody>
   * <tr>
   * <td>&lt;default Namespace URI&gt;</td>
   * <td><code>XMLConstants.DEFAULT_NS_PREFIX</code> ("")
   * </td>
   * </tr>
   * <tr>
   * <td>bound Namespace URI</td>
   * <td>prefix bound to Namespace URI in the current scope, if multiple
   * prefixes are bound to the Namespace URI in the current scope, a single
   * arbitrary prefix, whose choice is implementation dependent, is
   * returned</td>
   * </tr>
   * <tr>
   * <td>unbound Namespace URI</td>
   * <td><code>null</code></td>
   * </tr>
   * <tr>
   * <td><code>XMLConstants.XML_NS_URI</code>
   * ("http://www.w3.org/XML/1998/namespace")</td>
   * <td><code>XMLConstants.XML_NS_PREFIX</code> ("xml")</td>
   * </tr>
   * <tr>
   * <td><code>XMLConstants.XMLNS_ATTRIBUTE_NS_URI</code>
   * ("http://www.w3.org/2000/xmlns/")</td>
   * <td><code>XMLConstants.XMLNS_ATTRIBUTE</code> ("xmlns")</td>
   * </tr>
   * <tr>
   * <td><code>null</code></td>
   * <td><code>IllegalArgumentException</code> is thrown</td>
   * </tr>
   * </tbody>
   * </table>
   *
   * @param namespaceURI URI of Namespace to lookup
   * @return prefix bound to Namespace URI in current context
   * @throws IllegalArgumentException When <code>namespaceURI</code> is <code>null</code>
   */
  public String getPrefix(String namespaceURI) {
    return mPrefixByUri.get(namespaceURI);
  }

  /**
   * Get all prefixes bound to a Namespace URI in the current scope. (the XML file)
   *
   * <p>NOTE: Multiple prefixes bound to a similar Namespace URI will be normalized to the first
   * prefix defined. Still the namespace attributes exist in the XML as inner value prefixes might
   * be used.
   *
   * <p><strong>The <code>Iterator</code> is <em>not</em> modifiable. e.g. the <code>remove()</code>
   * method will throw <code>UnsupportedOperationException</code>.</strong>
   *
   * <p>When requesting prefixes by Namespace URI, the following table describes the returned
   * prefixes value for all Namespace URI values:
   *
   * <table border="2" rules="all" cellpadding="4">
   * <thead>
   * <tr>
   * <th align="center" colspan="2"><code>
   *         getPrefixes(namespaceURI)</code> return value for specified Namespace
   * URIs</th>
   * </tr>
   * <tr>
   * <th>Namespace URI parameter</th>
   * <th>prefixes value returned</th>
   * </tr>
   * </thead>
   * <tbody>
   * <tr>
   * <td>bound Namespace URI, including the &lt;default Namespace URI&gt;</td>
   * <td>
   * <code>Iterator</code> over prefixes bound to Namespace URI in the current
   * scope in an arbitrary,
   * <strong>implementation dependent</strong>, order
   * </td>
   * </tr>
   * <tr>
   * <td>unbound Namespace URI</td>
   * <td>empty <code>Iterator</code></td>
   * </tr>
   * <tr>
   * <td><code>XMLConstants.XML_NS_URI</code>
   * ("http://www.w3.org/XML/1998/namespace")</td>
   * <td><code>Iterator</code> with one element set to
   * <code>XMLConstants.XML_NS_PREFIX</code> ("xml")</td>
   * </tr>
   * <tr>
   * <td><code>XMLConstants.XMLNS_ATTRIBUTE_NS_URI</code>
   * ("http://www.w3.org/2000/xmlns/")</td>
   * <td><code>Iterator</code> with one element set to
   * <code>XMLConstants.XMLNS_ATTRIBUTE</code> ("xmlns")</td>
   * </tr>
   * <tr>
   * <td><code>null</code></td>
   * <td><code>IllegalArgumentException</code> is thrown</td>
   * </tr>
   * </tbody>
   * </table>
   *
   * @param namespaceURI URI of Namespace to lookup
   * @return <code>Iterator</code> for all prefixes bound to the Namespace URI in the current scope
   * @throws IllegalArgumentException When <code>namespaceURI</code> is <code>null</code>
   */
  public Iterator<String> getPrefixes(String namespaceURI) {
    Set<String> prefixes = mDuplicatePrefixesByUri.get(namespaceURI);
    if (prefixes == null) {
      prefixes = new HashSet<String>();
    }
    String givenPrefix = mPrefixByUri.get(namespaceURI);
    if (givenPrefix != null) {
      prefixes.add(givenPrefix);
    }
    return prefixes.iterator();
  }

  /** @return a map of namespaces, where the URI is the key and the prefix is the value */
  Map<String, String> getMapNamespacePrefixByUri() {
    return mPrefixByUri;
  }

  /**
   * Adds a new Namespace to the DOM. Making the prefix usable with JDK <code>XPath</code>. All
   * namespace attributes will be written to the root element during later serialization of the DOM
   * by the <code>OdfPackage</code>.
   *
   * @param prefix of the namespace to be set to this DOM
   * @param uri of the namespace to be set to this DOM
   * @return the namespace that was set. If an URI was registered before to the DOM, the previous
   *     prefix will be taken. In case of a given prefix that was already registered, but related to
   *     a new URI, the prefix will be adapted. The new prefix receives the suffix '__' plus
   *     integer, e.g. "__1" for the first duplicate and "__2" for the second.
   */
  public OdfNamespace setNamespace(String prefix, String uri) {
    // collision detection, when a new prefix/URI pair exists
    OdfNamespace newNamespace = null;
    // Scenario a) the URI already registered, use existing prefix
    // but save all others for the getPrefixes function. There might be still some
    // in attribute values using prefixes, that were not exchanged.
    String existingPrefix = mPrefixByUri.get(uri);
    if (existingPrefix != null) {
      // Use the existing prefix of the used URL, neglect the given
      newNamespace = OdfNamespace.newNamespace(existingPrefix, uri);

      // Add the new prefix to the duplicate prefix map for getPrefixes(String uri)
      Set<String> prefixes = mDuplicatePrefixesByUri.get(uri);
      if (prefixes == null) {
        prefixes = new HashSet<String>();
        mDuplicatePrefixesByUri.put(uri, prefixes);
      }
      prefixes.add(prefix);
    } else {
      // Scenario b) the prefix already exists and the URI does not exist
      String existingURI = mUriByPrefix.get(prefix);
      if (existingURI != null && !existingURI.equals(uri)) {
        // Change the prefix appending "__" plus counter.
        int i = 1;
        do {
          int suffixStart = prefix.lastIndexOf("__");
          if (suffixStart != -1) {
            prefix = prefix.substring(0, suffixStart);
          }
          // users have to take care for their attribute values using namespace prefixes.
          prefix = prefix + "__" + i;
          i++;
          existingURI = mUriByPrefix.get(prefix);
        } while (existingURI != null && !existingURI.equals(uri));
      }
      newNamespace = OdfNamespace.newNamespace(prefix, uri);
      mPrefixByUri.put(uri, prefix);
      mUriByPrefix.put(prefix, uri);
    }
    // if the file Dom is already associated to parsed XML add the new namespace to the root element
    Element root = getRootElement();
    if (root != null) {
      root.setAttributeNS("http://www.w3.org/2000/xmlns/", "xmlns:" + prefix, uri);
    }
    return newNamespace;
  }

  /**
   * Adds a new Namespace to the DOM. Making the prefix usable with JDK <code>XPath</code>. All
   * namespace attributes will be written to the root element during later serialization of the DOM
   * by the <code>OdfPackage</code>.
   *
   * @param name the namespace to be set
   * @return the namespace that was set. If an URI was registered before to the DOM, the previous
   *     prefix will be taken. In case of a given prefix that was already registered, but related to
   *     a new URI, the prefix will be adapted. The new prefix receives the suffix '__' plus
   *     integer, e.g. "__1" for the first duplicate and "__2" for the second.
   */
  public OdfNamespace setNamespace(NamespaceName name) {
    return setNamespace(name.getPrefix(), name.getUri());
  }

  /**
   * Get in-content metadata cache model
   *
   * @return in-content metadata cache model
   */
  public Map<Node, Model> getInContentMetadataCache() {
    return this.inCententMetadataCache;
  }

  /**
   * Update the in content metadata of the node. It should be called whenever the xhtml:xxx
   * attributes values of the node are changed.
   *
   * @param the node, whose in content metadata will be updated
   */
  public void updateInContentMetadataCache(Node node) {
    this.getInContentMetadataCache().remove(node);
    DOMRDFaParser parser = DOMRDFaParser.createInstance(this.sink);
    String baseUri = Util.getRDFBaseUri(mPackage.getBaseURI(), mPackagePath);
    parser.setBase(baseUri);
    parser.parse(node);
  }

  /** @return the RDF metadata of all the bookmarks within the dom */
  public Model getBookmarkRDFMetadata() {
    return BookmarkRDFMetadataExtractor.newBookmarkTextExtractor().getBookmarkRDFMetadata(this);
  }

  /**
   * The end users needn't to care of this method, which is used by BookmarkRDFMetadataExtractor
   *
   * @return the JenaSink
   */
  public JenaSink getSink() {
    return sink;
  }

  /**
   * @return counter for ids that are not allowed to be saved (otherwise it is not guaranteed that
   *     this id is unique)
   */
  public String getNextMarkupId() {
    return getDocument().getPackage().getNextMarkupId();
  }
}