/*****************************************************/
/*          This java file is a part of the          */
/*                                                   */
/*           -  Plouf's Java IRC Client  -           */
/*                                                   */
/*   Copyright (C)  2002 - 2004 Philippe Detournay   */
/*                                                   */
/*         All contacts : theplouf@yahoo.com         */
/*                                                   */
/*  PJIRC is free software; you can redistribute     */
/*  it and/or modify it under the terms of the GNU   */
/*  General Public License as published by the       */
/*  Free Software Foundation; version 2 or later of  */
/*  the License.                                     */
/*                                                   */
/*  PJIRC is distributed in the hope that it will    */
/*  be useful, but WITHOUT ANY WARRANTY; without     */
/*  even the implied warranty of MERCHANTABILITY or  */
/*  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU   */
/*  General Public License for more details.         */
/*                                                   */
/*  You should have received a copy of the GNU       */
/*  General Public License along with PJIRC; if      */
/*  not, write to the Free Software Foundation,      */
/*  Inc., 59 Temple Place, Suite 330, Boston,        */
/*  MA  02111-1307  USA                              */
/*                                                   */
/*****************************************************/

package irc;

/**
 * LinkedListNode.
 */
class LinkedListNode {
	/**
	 * Next node.
	 */
	public LinkedListNode next = null;
	/**
	 * Previous node.
	 */
	public LinkedListNode prev = null;
	/**
	 * Node content.
	 */
	public Object item = null;
}

/**
 * A very simple linked list.
 */
public class LinkedList {
	private int _size;
	private LinkedListNode _head;
	private LinkedListNode _tail;

	/**
	 * Create a new, empty linked list.
	 */
	public LinkedList() {
		_head = new LinkedListNode();
		_tail = new LinkedListNode();
		_head.next = _tail;
		_tail.prev = _head;
		_size = 0;
	}

	/**
	 * Get the size of the list.
	 * 
	 * @return list size.
	 */
	public int size() {
		return _size;
	}

	/**
	 * Add the given object at the end of the list.
	 * 
	 * @param obj
	 *          object to add.
	 */
	public void addLast(Object obj) {
		LinkedListNode node = new LinkedListNode();
		node.item = obj;
		node.next = _tail;
		node.prev = _tail.prev;
		node.prev.next = node;
		node.next.prev = node;
		_size++;
	}

	/**
	 * Remove and return the first object of the list.
	 * 
	 * @return removed object.
	 * @throws RuntimeException
	 *           if list is empty.
	 */
	public Object removeFirst() {
		if (_size == 0)
			throw new RuntimeException("List empty");
		LinkedListNode node = _head.next;

		node.next.prev = _head;
		_head.next = node.next;
		_size--;
		return node.item;
	}

}