package jp.ac.u_ryukyu.ie.cr.shoshi.jungle.persistent;

public class NullJournal implements Journal
{
	private static final NullChangeListWriter NULL_WRITER = new NullChangeListWriter();
	private static final NullChangeListReader NULL_READER = new NullChangeListReader();
	
	@Override
	public ChangeListReader getReader()
	{
		return NULL_READER;
	}

	@Override
	public ChangeListWriter getWriter()
	{
		return NULL_WRITER;
	}
	
	private static class NullChangeListWriter implements ChangeListWriter
	{
		@Override
		public Result write()
		{
			return Result.SUCCESS;
		}
	}
	
	private static class NullChangeListReader implements ChangeListReader
	{
		@Override
		public ChangeListReader newReader()
		{
			return this;
		}

		@Override
		public ChangeList read()
		{
			return null;
		}
	}
}