+ /**
+ * <b>Optional:</b> <i>If possible</i>, this method will return a
+ * rendering of the input region (for example, if the input is a
+ * region of characters, it would be those characters) --
+ * otherwise, returns null. In any case, the string returned
+ * will be no more than <tt>maxLength</tt> characters long;
+ * typically ellipses will be inserted to perform truncation.
+ */
+ public abstract String showRegion(Region<Token> r, int maxLength);
+
+ /** <font color=purple>a location (position) in the input stream <i>between tokens</i></font> */
+ public static interface Location<Token> extends Comparable<Location> {
+
+ /** return the region between this location and <tt>loc</tt> */
+ public Region<Token> createRegion(Location<Token> loc);