Having fun with custom collections!

using System;
using System.Collections.Generic;
using System.Linq;

namespace Alphabet
{
	internal class WesternAlphabetEnumerator : IEnumerator<string>
	{

		private IEnumerable<string> _alphabet;
		private int _position;
		private int _max;

		public WesternAlphabetEnumerator(IEnumerable<string> alphabet)
		{
			_alphabet = alphabet;
			// The position start at -1 and represents the current index.
			// A foreach loop calls MoveNext and _position is set to 0.
			_position = -1;
			// Get the maximum number of items in the alphabet.
			// When the maximum index is reached we are at the end of the alphabet.
			_max = _alphabet.Count() - 1;
		}

		/// <summary>
		/// Returns the item at the current index in a foreach loop.
		/// </summary>
		/// <remarks>Is only called when MoveNext returned true.</remarks>
		public string Current
		{
			get { return _alphabet.ElementAt(_position); }
		}

		/// <summary>
		/// This is the non-generic version of Current.
		/// </summary>
		object System.Collections.IEnumerator.Current
		{
			get { return this.Current; }
		}

		/// <summary>
		/// Moves to the next item in a collection.
		/// If this returns true it means the index is not the last index
		/// in the collection yet. If true is returned the Current Property
		/// is called.
		/// </summary>
		/// <returns>True if the last index has not been reached yet.</returns>
		public bool MoveNext()
		{
			if (_position < _max)
			{
				_position += 1;
				return true;
			}
			return false;
		}

		/// <summary>
		/// For interoperability with COM. Not supported/implemented.
		/// </summary>
		void System.Collections.IEnumerator.Reset()
		{
			throw new NotImplementedException();
		}

		/// <summary>
		/// Not implemented. This is used in rare cases where the Enumerator
		/// opens up a database connection or files and needs to close them.
		/// </summary>
		public void Dispose()
		{
			// Do not throw an exception here.
			// This method is called after every loop!
		}

	}
}