1 package edu.berkeley.sbp;
2 import edu.berkeley.sbp.util.*;
3 import edu.berkeley.sbp.*;
4 import edu.berkeley.sbp.*;
7 import java.lang.reflect.*;
8 import java.lang.ref.*;
10 /** <font color=green>the root superclass for all components of the grammar (terminals, nonterminals, literals, etc)</font> */
11 public abstract class Element {
13 /** sorry, you can't make up new, custom elements */
16 abstract StringBuffer toString(StringBuffer sb);
18 /** returns the Forest resulting from matching this element against the empty string */
19 Forest epsilonForm() { throw new Error("element " + this + " has no epsilon form"); }