[antlr-interest] Syntactic predicate ignored?

[Ken Williams]

I am surprised that the following grammar matches "xli" as a STATE rather
than as a ROMAN.  It's like it's completely ignoring the syntactic predicate
on STATE.  Anyone have any insight into what's going on?

I'm using:

  ANTLRWorks   1.4 
  ANTLR   3.2 Sep 23, 2009 12:02:23
  StringTemplate   3.2.1
  Java   1.6.0_20 (Apple Inc.)


------------------------
grammar testg;
options { output=AST; }

cite    : token+ EOF ;
token    :  ROMAN | STATE ;

fragment LETTER : 'a'..'z' ;
STATE: (('mi'|'dc') (EOF | ~LETTER)) => LETTER+
       {System.err.println("Found state");};

// From Perl 6 Exegesis on pattern matching
//http://search.cpan.org/~lichtkind/Perl6-Doc-0.36/lib/Perl6/Doc/Design/E05.
pod

fragment ROMANPAT
    :    'm'* ('d'?('c'('c'('c')?)?)?|'c'('d'|'m'))
              ('l'?('x'('x'('x')?)?)?|'x'('l'|'c'))
              ('v'?('i'('i'('i')?)?)?|'i'('v'|'x'))
    ;

ROMAN : (ROMANPAT (EOF | ~LETTER)) => ROMANPAT
        {System.err.println("Found roman");};
------------------------




-- 
Ken Williams
Sr. Research Scientist
Thomson Reuters
Phone: 651-848-7712
ken.williams at thomsonreuters.com