package list.dl.algo;

import list.dl.DLList;

/**
 * Counts the number of elements to the left the host.
 */
public class LeftCount implements IAlgoLeft
{
	final public static LeftCount Singleton = new LeftCount();
	private LeftCount()
	{
	}

	/**
	 * @param hostList 
	 * @param inputParam 
	 * @return 
	 */
	public Object leftEndCase(DLList hostList, Object inputParam)
	{
		return new Integer (0);
	}

	/**
	 * @param hostList 
	 * @param inputParam 
	 * @return 
	 */
	public Object dataNodeCase(DLList hostList, Object inputParam)
	{
      Integer restCount = (Integer) hostList.getLeftRest ().executeLeft (this, null);
		return new Integer (1 + restCount.intValue ());
	}
}