[Grammatica-users] JML Parser

[Brandon Silverstein]

Hello,

I am new to Grammatica and I am trying to develop a JML parser in C#.  
I am converting the grammar found at 
http://www.cs.iastate.edu/~leavens/JML/jmlrefman/jmlrefman_20.html to a 
format that Grammatica can understand and parse.  After creating a 
whole bunch of tokens and reformatting the file, I am getting 
individual errors saying:

production 'myProduction' is invalid, as zero elements can be matched 
(minimum is one)

I've tried to figure out what the problem is, and I think it has 
something to do with reformatting the "optional" text in the original 
JML file.  Anytime a ... appears, I surround the optional text with { 
brackets }.  Anyway, I made a test file with the example production 
shown in the Grammatica reference manual.

Prod = "1"? | "2"* ...... and so on.  When I try to parse this file, I 
get the same error message.  I am intrigued by the statement right 
below the yellow box where this production is located in the manual.  
It states that Grammatica does not allow null production alternatives, 
but "the same result can be obtained by making all references to the 
production optional."  I still can't figure out how to solve this 
problem.

Any help is appreciated.

Thanks,
Brandon