package edu.rice.cs.dxn.QFList;

/**
 * Mutable quasi-functional linear recursive structure.
 * @author Dung X. Nguyen  Copyright 1999 - All rights reserved.
 * @since 10/21/99
 */
public class QFList
{
	/** @SBGen Variable (,head,,128)   */
	private IState _head;

	/** @SBGen Constructor   */
	 public QFList ()
	{
		_head = NullNode.singleton;
   }

	/**
	 * @param dat data to insert at this node
	 */
	public final void insertFront (Object dat)
	{
		_head.insertFront (dat, this);
	}

	/**
	 * @return Returns this node's first
	 */
	public final Object removeFront ()
	{
		return _head.removeFront (this);
	}

	/**
	 * @return Gets the data from this node
	 */
	public final Object getFirst()
	{
		return _head.getFirst (this);
	}

	/**
	 * @param dat new data for this node
	 */
	public final void setFirst (Object dat)
	{
		_head.setFirst (dat, this);
	}

	/**
	 * @return gets the rest of the structure
	 */
	public final QFList getRest ()
	{
		return _head.getRest (this);
	}

	/**
	 * @param tail sets a new tail for this node
	 */
	public final void setRest (QFList tail)
	{
		_head.setRest (tail, this);
	}

	public final Object execute (IAlgo visitor, Object input)
	{
	    return _head.execute (visitor, input, this);
	}

// Package access only:

   /**
   * Initiazes this QFList with a given head node.
   * @param node null != node.
   */
   QFList (IState node)
   {
      _head = node;
   }

	/**
	 * @param head
	 */
	final void setHead (IState head)
	{
		_head = head;
	}

	/**
	 * @return
	 */
	final IState getHead ()
	{
		return (_head);
	}

}