Efficient data entry through browser automation

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace NCrawler
{
	public abstract class Selector
	{
		protected abstract IEnumerable<HtmlElement> SelectCore(HtmlDocument document);

		public IEnumerable<HtmlElement> Select(HtmlDocument document)
		{
			var elements = SelectCore(document);
			if(selectChildren != null)
				return elements.SelectMany(e => e.Children.OfType<HtmlElement>()).Where(selectChildren);
			return elements;
		}

		Func<HtmlElement, bool> selectChildren;
		public Selector SelectChildren(Func<HtmlElement, bool> predicate)
		{
			selectChildren = predicate;
			return this;
		}

		public void ForEach(HtmlDocument document, Action<HtmlElement> action)
		{
			foreach(var element in Select(document))
				action(element);
		}


		public static implicit operator Selector(string id)
		{
			return new IdSelector(id);
		}
	}

	public class IdSelector : Selector
	{
		public IdSelector(string id)
		{
			_Id = id;
		}
		private readonly string _Id;
		public string Id
		{
			get
			{
				return _Id;
			}
		}


		protected override IEnumerable<HtmlElement> SelectCore(HtmlDocument document)
		{
			yield return document.GetElementById(Id);
		}
	}
	public class ClassSelector : Selector
	{
		public ClassSelector(string className)
		{
			_ClassName = className;
		}
		private readonly string _ClassName;
		public string ClassName
		{
			get
			{
				return _ClassName;
			}
		}

		protected override IEnumerable<HtmlElement> SelectCore(HtmlDocument document)
		{
			foreach(HtmlElement element in document.All)
			{
				dynamic dom = element.DomElement;
				string className = dom.className;
				if(className == ClassName)
					yield return element;
			}
		}
	}

}