XmlLocationAnnotator.java example

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hapi-fhir-master
package org.hl7.fhir.dstu3.utils;

import java.util.Stack;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.UserDataHandler;
import org.w3c.dom.events.Event;
import org.w3c.dom.events.EventListener;
import org.w3c.dom.events.EventTarget;
import org.w3c.dom.events.MutationEvent;
import org.xml.sax.Attributes;
import org.xml.sax.Locator;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.LocatorImpl;
import org.xml.sax.helpers.XMLFilterImpl;

// http://javacoalface.blogspot.com.au/2011/04/line-and-column-numbers-in-xml-dom.html

public class XmlLocationAnnotator extends XMLFilterImpl  {

  private Locator locator;
  private Stack<Locator> locatorStack = new Stack<Locator>();
  private Stack<Element> elementStack = new Stack<Element>();
  private UserDataHandler dataHandler = new LocationDataHandler();

  public XmlLocationAnnotator(XMLReader xmlReader, Document dom) {
      super(xmlReader);

      // Add listener to DOM, so we know which node was added.
      EventListener modListener = new EventListener() {
          @Override
          public void handleEvent(Event e) {
              EventTarget target = ((MutationEvent) e).getTarget();
              elementStack.push((Element) target);
          }
      };
      ((EventTarget) dom).addEventListener("DOMNodeInserted", modListener, true);
  }

  @Override
  public void setDocumentLocator(Locator locator) {
      super.setDocumentLocator(locator);
      this.locator = locator;
  }

  @Override
  public void startElement(String uri, String localName,
          String qName, Attributes atts) throws SAXException {
      super.startElement(uri, localName, qName, atts);

      // Keep snapshot of start location,
      // for later when end of element is found.
      locatorStack.push(new LocatorImpl(locator));
  }

  @Override
  public void endElement(String uri, String localName, String qName)
          throws SAXException {

      // Mutation event fired by the adding of element end,
      // and so lastAddedElement will be set.
      super.endElement(uri, localName, qName);
     
      if (locatorStack.size() > 0) {
          Locator startLocator = locatorStack.pop();
         
          XmlLocationData location = new XmlLocationData(
                  startLocator.getSystemId(),
                  startLocator.getLineNumber(),
                  startLocator.getColumnNumber(),
                  locator.getLineNumber(),
                  locator.getColumnNumber());
         Element lastAddedElement = elementStack.pop();
         
          lastAddedElement.setUserData(
                  XmlLocationData.LOCATION_DATA_KEY, location,
                  dataHandler);
      }
  }

  // Ensure location data copied to any new DOM node.
  private class LocationDataHandler implements UserDataHandler {

      @Override
      public void handle(short operation, String key, Object data,
              Node src, Node dst) {
         
          if (src != null && dst != null) {
              XmlLocationData locatonData = (XmlLocationData)
                      src.getUserData(XmlLocationData.LOCATION_DATA_KEY);
             
              if (locatonData != null) {
                  dst.setUserData(XmlLocationData.LOCATION_DATA_KEY,
                          locatonData, dataHandler);
              }
          }
      }
  }
}