using System.Collections.Generic;

public class NullJournal : Journal {

	private static NullChangeListWriter NULL_WRITER = new NullChangeListWriter();
	private static NullChangeListReader NULL_READER = new NullChangeListReader();

	public ChangeListReader getReader() {
		return NULL_READER;
	}

	public ChangeListWriter getWriter() {
		return NULL_WRITER;
	}

	private class NullChangeListWriter : ChangeListWriter{
		public Result write(ChangeList operations){
			return Result.SUCCESS;
		}
	}

	private class NullChangeListReader : ChangeListReader { 
		public ChangeListReader newReader() {
			return this;
		}

		public ChangeList read() {
			return null;
		}

		public IEnumerator<ChangeList> iterator() {
			return null;
		}

	}

}