//
//   This file contains the C# code from Program 7.21 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/pgm07_21.txt
//
public class PolynomialAsOrderedList : Polynomial
{
    OrderedList list;

    public PolynomialAsOrderedList()
	{ list = new OrderedListAsLinkedList(); }

    public override void Add(Term term)
	{ list.Insert(term); }

    internal class DifferentiatingVisitor : AbstractVisitor
    {
	public override void Visit(object obj)
	{
	    Term term = obj as Term;
	    if (term != null)
		term.Differentiate();
	}
    }

    public override void Differentiate()
    {
	Visitor visitor = new DifferentiatingVisitor();
	list.Accept(visitor);
	ComparableObject zeroTerm = list.Find(new Term(0, 0));
	if (zeroTerm != null)
	    list.Withdraw(zeroTerm);
    }
    // ...
}