I have been using the development version of grammatica (1.5 alpha 2) and it looks to me like there is a bug in the parser generation.
The attached grammar should do as a test case, by passing to it :
{start a b c}
i get:
net.percederberg.grammatica.parser.ParserLogException: unexpected token "b" <IDENT>, expected "}", on line 1 column: 10 at net.percederberg.grammatica.parser.Parser.reset
(Parser.java:271) at net.percederberg.grammatica.parser.Parser.parse(Parser.java:303) ... A workaround for this simple case is to eliminate the Sentence production by inlining it.
Unfortunately I have a grammar file that is much bigger where it is difficult to use such a workaround
without increasing the complexity.