X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FElement.java;h=27a3ee64edc3220951fd1bb88e3833bd9d46fefe;hb=6e0ac72335464f3151c0621cc02433800d13c18a;hp=5f55be697e74ed325aa9cc2d4c83b3f2aefc7ecc;hpb=2690f6c749f117a103c57d651d89f1b4fbf1316d;p=sbp.git
diff --git a/src/edu/berkeley/sbp/Element.java b/src/edu/berkeley/sbp/Element.java
index 5f55be6..27a3ee6 100644
--- a/src/edu/berkeley/sbp/Element.java
+++ b/src/edu/berkeley/sbp/Element.java
@@ -1,25 +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 {
+/**
+ *
+ * the root superclass for all components of the grammar (terminals,
+ * nonterminals, literals, etc)
+ *
+ */
+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 rp);
+ /** a more verbose version of toString() for displaying whole grammars */
+ abstract StringBuffer toString(StringBuffer sb);
- abstract Topology toAtom();
- 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;
- }
}