X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FElement.java;h=27a3ee64edc3220951fd1bb88e3833bd9d46fefe;hp=b199a23ca52f943964a5afb2a9002e94f42a54d4;hb=dc9bb3a45ed306e2e35549076842b3e74efecb48;hpb=0a0227b9180534d2a431f3d6e08a398bde2244c4

diff --git a/src/edu/berkeley/sbp/Element.java b/src/edu/berkeley/sbp/Element.java
index b199a23..27a3ee6 100644
--- a/src/edu/berkeley/sbp/Element.java
+++ b/src/edu/berkeley/sbp/Element.java
@@ -1,24 +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 {
+
+    /** sorry, you can't make up new, custom elements */
+    Element() { }
 
-    /** add all positions reachable from the start of this Element to @rp */
-    abstract void reachable(HashSet<Sequence.Position> rp);
+    /** a more verbose version of toString() for displaying whole grammars */
+    abstract StringBuffer toString(StringBuffer sb);
 
-    Forest epsilonForm() { throw new Error("no epsilon form: " + this); }
-    final boolean possiblyEpsilon(Walk.Cache cache)   {
-        Boolean ret = cache==null ? null : cache.possiblyEpsilon.get(this);
-        if (ret != null) return ret.booleanValue();
-        ret = new Walk.PossiblyEpsilon().walk(this) ? Boolean.TRUE : Boolean.FALSE;
-        if (cache != null) cache.possiblyEpsilon.put(this, ret);
-        return ret;
-    }
 }