//
//   This file contains the C# code from Program 4.16 of
//   "Data Structures and Algorithms
//    with Object-Oriented Design Patterns in C#"
//   by Bruno R. Preiss.
//
//   Copyright (c) 2001--2002 by Bruno R. Preiss, P.Eng.  All rights reserved.
//
//   http://www.brpreiss.com/books/opus6/programs/pgm04_16.txt
//
public class LinkedList
{
    protected Element head;
    protected Element tail;

    public object First
    {
	get
	{
	    if (head == null)
		throw new ContainerEmptyException();
	    return head.datum;
	}
    }
    
    public object Last
    {
	get
	{
	    if (tail == null)
		throw new ContainerEmptyException();
	    return tail.datum;
	}
    }
    // ...
}