[jdom-interest] XML "diff"

[Kenneth Ellefsen]

Hi.

Heres something I made a while ago to create diffs.

Works fine in my case where el2 is the root of a document that is a
subset of the full document that el1 is the root of.



/**
 * This method is recursive.
 * @param el1 Root of the full "document"
 * @param el2 Root of the subset "document"
 * @return The root of the diff "document"
 */
private Element diff(Element el1, Element el2){
   Element el = null;
   
   if(!equals(el1, el2)){
      el = new Element(el2.getName());
      java.util.List a = el2.getAttributes();
      int size = a.size();
      for(int i=0; i<size; i++)
         el.setAttribute( (Attribute) ( (Attribute)a.get(i) ).clone());
   }

   java.util.List l1 = el1.getChildren();
   java.util.List l2 = el2.getChildren();
   Iterator li1 = l1.iterator();
   Iterator li2 = l2.iterator();
   while(li1.hasNext()){
      Element e = diff((Element)li1.next(),   (Element)li2.next());
      if(e != null){
         if(el == null){
            el = new Element(el2.getName());
            java.util.List a = el2.getAttributes();
            int size = a.size();
            for(int i=0; i<size; i++)
              el.setAttribute((Attribute)((Attribute)a.get(i)).clone());
            }
            el.addContent(e);
         }  
      }
   return el;
}

private boolean equals(Element el1, Element el2){
      
   java.util.List l1 = el1.getAttributes();
   java.util.List l2 = el2.getAttributes();
   Iterator li1 = l1.iterator();
   while(li1.hasNext()){
      Iterator li2 = l2.iterator();
      Attribute at1 = (Attribute)li1.next();
      Attribute at2 = (Attribute)li2.next();
      while(!at1.getName().equals(at2.getName())&&li2.hasNext())
         at2 = (Attribute)li2.next();
        
      if(!at1.getValue().equals(at2.getValue())){
         return false;
      }
   }
   return true;
}