ROT13XML

import java.io.IOException;
import nu.xom.*;

public class ROT13XML {

    // note use of recursion
    public static void encode(Node node) {
    
        if (node instanceof Text) {
          Text text = (Text) node;
          String data = text.getValue();
          text.setValue(rot13(data));
        }
        
        // recurse the children
        for (int i = 0; i < node.getChildCount(); i++) {
            encode(node.getChild(i));
        } 
    
    }
  
    public static String rot13(String s) {
    
        StringBuffer out = new StringBuffer(s.length());
        for (int i = 0; i < s.length(); i++) {
          int c = s.charAt(i);
          if (c >= 'A' && c <= 'M') out.append((char) (c+13));
          else if (c >= 'N' && c <= 'Z') out.append((char) (c-13));
          else if (c >= 'a' && c <= 'm') out.append((char) (c+13));
          else if (c >= 'n' && c <= 'z') out.append((char) (c-13));
          else out.append((char) c);
        } 
        return out.toString();
    
    }

  public static void main(String[] args) {

    if (args.length <= 0) {
      System.out.println("Usage: java ROT13XML URL");
      return;
    }
    
    String url = args[0];
    
    try {
      Builder parser = new Builder();
      
      // Read the document
      Document document = parser.build(url); 
      
      // Modify the document
      ROT13XML.encode(document);

      // Write it out again
      System.out.println(document.toXML());

    }
    catch (IOException ex) { 
      System.out.println(
      "Due to an IOException, the parser could not encode " + url
      ); 
    }
    catch (ParsingException ex) { 
      System.out.println(ex);
    }
     
  } // end main

}