[antlr-interest] Predicate Syntax Problem

[Bill Venners]

Hello,

I am not sure how to add a predicate to one element of an OR  
expression in ANLTR 3.

passedDecl
     :    'not-null'? ('byte' | 'short' | 'int' | 'long' | 'boolean'  
| 'float' | 'double'
          | 'char' | ID_UP )^ { isTypeName($ID_UP.getText()) }?
          ID_DOWN { isVarName($ID_DOWN.getText()) }?
     ;

This is apparently valid grammar syntax, but the $ID_UP doesn't work.  
I get:

com/artima/view/ViewParser.java:497: cannot find symbol
symbol  : variable $ID_UP
location: class com.artima.view.ViewParser
             if ( !( isTypeName($ID_UP.getText()) ) ) {

I am unable to find any help in the documentation I can find. Can  
someone help me understand what I should do here? What I'd like to  
accomplish is to kill the parse if the ID_UP variable returns false  
when passed to isTypeName().

Thanks.

Bill
----
Bill Venners
President
Artima, Inc.
http://www.artima.com

P.S. I also tried the following, which are apparently not valid ANTLR  
3 grammar syntax:

passedDecl
     :    'not-null'? ('byte' | 'short' | 'int' | 'long' | 'boolean'  
| 'float' | 'double'
          | 'char' | ID_UP { isTypeName($ID_UP.getText()) }?)^  
ID_DOWN { isVarName($ID_DOWN.getText()) }?
     ;


passedDecl
     :    'not-null'? ('byte' | 'short' | 'int' | 'long' | 'boolean'  
| 'float' | 'double'
          | 'char' | ID_UP ){ isTypeName($ID_UP.getText()) }?^  
ID_DOWN { isVarName($ID_DOWN.getText()) }?
     ;