implementato nodeposition con to string e reverse. aggiunto copyright

position/PositionList.java

@@ -0,0 +1,40 @@
+package position;
+import java.util.Iterator;
+import  exceptions.*;
+
+/**
+ * An interface for positional lists.
+ * @author Roberto Tamassia, Michael Goodrich
+ */
+//Copyright (c) 2003 Brown University, Providence, RI
+//Additional modifications and methods by xgiovio
+public interface PositionList<E>  {
+
+
+  public int size();
+
+  public boolean isEmpty();
+
+  public Position<E> first();
+
+  public Position<E> last();
+
+  public Position<E> next(Position<E> p)      throws InvalidPositionException, BoundaryViolationException;
+
+  public Position<E> prev(Position<E> p)      throws InvalidPositionException, BoundaryViolationException;
+
+  public void addFirst(E e);
+
+  public void addLast(E e);
+
+  public void addAfter(Position<E> p, E e)         throws InvalidPositionException;
+
+  public void addBefore(Position<E> p, E e)       throws InvalidPositionException;
+
+  public E remove(Position<E> p) throws InvalidPositionException;
+
+  public E set(Position<E> p, E e) throws InvalidPositionException;
+
+
+}
+