X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FElement.java;h=27a3ee64edc3220951fd1bb88e3833bd9d46fefe;hb=5c4157c1118401c4223ff485e9531fc3ba851be2;hp=0d7fb84f583ea0ba9594a9b23cf88d83998afafc;hpb=6b24a8ff6410a47d7290c2b42587fd8a8c5341e8;p=sbp.git

diff --git a/src/edu/berkeley/sbp/Element.java b/src/edu/berkeley/sbp/Element.java
index 0d7fb84..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() { }
 
-    /** returns the Forest resulting from matching this element against the empty string */
-    Forest epsilonForm() { throw new Error("element " + this + " has no epsilon form"); }
+    /** a more verbose version of toString() for displaying whole grammars */
+    abstract StringBuffer toString(StringBuffer sb);
 
 }