Delegate-Based XML Processor for Configuring Objects from XML

/*
 * Created by: Otto von Wachter
 * Created: Saturday, August 19, 2006
 */

using System.Collections;
using System.Xml;

namespace XmlProcessor
{
	public class XmlProcessor
	{
		XmlTextReader rdr;		
		ArrayList configs = new ArrayList();
		Stack elementStack = new Stack();

		public XmlProcessor(XmlTextReader rdr)
		{
			this.rdr = rdr;
		}

		public void RegisterElementHandler(string elementName, ElementHandler handler)
		{
			ElementHandlerConfig config = new ElementHandlerConfig(elementName, handler);
			configs.Add(config);
		}
		
		public void Start()
		{
			bool lastElementEmpty = false;
			while (rdr.Read())
			{
				if (!rdr.IsStartElement())
				{
					//pop off because we reached a closing tag
					elementStack.Pop();
					continue;
				}
				else if (lastElementEmpty)
				{
					//pop off because this is not a sub-element of last
					elementStack.Pop();
				}
				Element parent = elementStack.Count == 0? null : (Element) elementStack.Peek(); 
				Element el = new Element(rdr.Name, parent);
				LoadAttributes(el);
				elementStack.Push(el);
				ElementHandler handler = FindHandler(rdr.Name);
				if (handler != null)
					handler(el);
				
				lastElementEmpty = rdr.IsEmptyElement;
			}
		}
			
		private ElementHandler FindHandler(string name)
		{
			ElementHandlerConfig config = null;
			for (int i = 0; i < configs.Count; i++)
			{
				ElementHandlerConfig cfg = (ElementHandlerConfig) configs[i];
				if (cfg.ElementName == name)
				{
					config = cfg;
					break;					
				}
			}
			return config != null ? config.handler : null;
		}

		private void LoadAttributes(Element element)
		{
			rdr.MoveToFirstAttribute();
			for (int col=0;col<rdr.AttributeCount;col++)
			{
				element.Attributes[rdr.Name]=rdr.Value;
				rdr.MoveToNextAttribute();
			}
			rdr.MoveToElement();			
		}
	}
	
	public class Element
	{
		public string Name; 
		public IDictionary Attributes = new Hashtable();
		public Element Parent;
		public object Peer;  //arbitrary object to associate with this element

		public Element(string name, Element parent)
		{
			Name = name;
			Parent = parent;
		}
		
		public override string ToString()
		{
			if (Parent != null) 
				return Parent.ToString() + "/" + Name;
			else 
				return Name;
		}

		public Element FindAncestorByElementName(string name)
		{
			Element cur = this;
			while (cur.Parent != null)
			{
				cur = cur.Parent;
				if (cur.Name == name)
					return cur;
			}
			return null;
		}		
	}
	
	public class ElementHandlerConfig
	{		
		public string ElementName;
		public ElementHandler handler;

		public ElementHandlerConfig(string elementName, ElementHandler handler)
		{
			ElementName = elementName;
			this.handler = handler;
		}
	}
	
	public delegate void ElementHandler(Element element);
}