X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FElement.java;h=27a3ee64edc3220951fd1bb88e3833bd9d46fefe;hp=33bfd8d7d08f5027e136aef1eaff959dfbf92ce7;hb=dc9bb3a45ed306e2e35549076842b3e74efecb48;hpb=5d18f5606c9296e6b0c5749f05fc68f358ace2f6

diff --git a/src/edu/berkeley/sbp/Element.java b/src/edu/berkeley/sbp/Element.java
index 33bfd8d..27a3ee6 100644
--- a/src/edu/berkeley/sbp/Element.java
+++ b/src/edu/berkeley/sbp/Element.java
@@ -1,18 +1,20 @@
+// (C) 2006-2007 all rights reserved; see LICENSE file for BSD-style license
+
 package edu.berkeley.sbp;
-import edu.berkeley.sbp.util.*;
-import edu.berkeley.sbp.*;
-import edu.berkeley.sbp.*;
-import java.io.*;
 import java.util.*;
-import java.lang.reflect.*;
-import java.lang.ref.*;
 
-/** the root superclass for all components of the grammar (terminals, nonterminals, literals, etc) */
-public abstract class Element {
+/**
+ *  <font color=green>
+ *  the root superclass for all components of the grammar (terminals,
+ *  nonterminals, literals, etc)
+ *  </font>
+ */
+public abstract class Element implements SequenceOrElement {
 
-    abstract StringBuffer toString(StringBuffer sb);
+    /** sorry, you can't make up new, custom elements */
+    Element() { }
 
-    /** if this element always matches exactly one token, return a topology covering exactly those possible tokens, otherwise <tt>null</tt> */
-    Forest epsilonForm() { return null; }
+    /** a more verbose version of toString() for displaying whole grammars */
+    abstract StringBuffer toString(StringBuffer sb);
 
 }