// This is code fragment 5.7 from the textbook.
// Instead of documentation, Goodrich & Tamassia wrote chapter 5.

public interface List {

  public int size();

  public boolean isEmpty();

  public boolean isFirst(Position p) throws InvalidPositionException;

  public boolean isLast(Position p) throws InvalidPositionException;

  public Position first() throws EmptyContainerException;

  public Position last() throws EmptyContainerException;

  public Position before (Position p)
    throws InvalidPositionException, BoundaryViolationException;

  public Position after (Position p)
    throws InvalidPositionException, BoundaryViolationException;

  public Position insertBefore (Position p, Object element)
    throws InvalidPositionException;

  public Position insertAfter (Position p, Object element)
    throws InvalidPositionException;

  public Position insertFirst(Object element);

  public Position insertLast(Object element);

  public Object remove(Position p) throws InvalidPositionException;

  public Object replaceElement (Position p, Object element)
    throws InvalidPositionException;

  public void swapElements (Position a, Position b)
    throws InvalidPositionException;

}