X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FElement.java;h=35678abfb3cba74d48b7f3eaf830373804a98e76;hb=a82ff8c049dd265ecf1d115d60e1be8ecb81a4c1;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..35678ab 100644
--- a/src/edu/berkeley/sbp/Element.java
+++ b/src/edu/berkeley/sbp/Element.java
@@ -1,3 +1,5 @@
+// Copyright 2006 all rights reserved; see LICENSE file for BSD-style license
+
 package edu.berkeley.sbp;
 import edu.berkeley.sbp.util.*;
 import edu.berkeley.sbp.*;
@@ -7,12 +9,16 @@ 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 {
+
+    /** sorry, you can't make up new, custom elements */
+    Element() { }
 
+    /** a more verbose version of toString() which should show the entire grammar */
     abstract StringBuffer toString(StringBuffer sb);
 
     /** returns the Forest resulting from matching this element against the empty string */
-    Forest epsilonForm() { throw new Error("element " + this + " has no epsilon form"); }
+    Forest<?> epsilonForm(Input.Region loc) { throw new Error("element " + this + " has no epsilon form"); }
 
 }