checkpoint

[sbp.git] / src / edu / berkeley / sbp / meta / MetaGrammarBindings.java

diff --git a/src/edu/berkeley/sbp/meta/MetaGrammarBindings.java b/src/edu/berkeley/sbp/meta/MetaGrammarBindings.java
index 8f322a5..0d9052c 100644 (file)
--- a/src/edu/berkeley/sbp/meta/MetaGrammarBindings.java
+++ b/src/edu/berkeley/sbp/meta/MetaGrammarBindings.java
@@ -265,7 +265,10 @@ public class MetaGrammarBindings extends AnnotationGrammarBindings {
     public static @bind.as        Seq  psx(Seq s)                        { return s; }
     public static @bind.as(":")   ElementNode   colon(String s, ElementNode e)             { return new Label(s, e); }
     public static @bind.as(")")   void close(String foo)                 { throw new Error("not supported"); }
-    public static @bind.as("()")  ElementNode   epsilon()                         { return new Constant(Union.epsilon); }
+    public static @bind.as("()")  ElementNode   epsilon()                         { return new Constant(epsilon); }
+
+    private static Union epsilon = new Union("()");
+    static { epsilon.add(Sequence.empty); }
 
     public static class NonTerminalReferenceNode extends ElementNode {
         public String nonTerminal;