Re: epsilon productions in Java CUP?

I'm not sure the following lines will help, but if we have the following:
non terminal EndOrElse, SeqCmds
terminal END, ELSE


Consider the following production:


EndOrElse ::= END {: RESULT = null; :}
                          | ELSE SeqCmds:cmd END {: RESULT = cmd; :};


the null or epsilon production is achieved in CUP by assigning the value
"null" to the Result.
The above production is intended to avoid the dangling if -then - else
problem.


        -- lee
.:*~*:._.:*~*:._.:*~*:._.:*~*:._.:*~*:._.:*~*:.


"Smith, Doug" <smith@sjfc.edu> wrote in message news:01-12-071...
> I'm looking for information on how to specify epsilon productions in Java
> CUP. For example if one wanted to specify the grammar of valid balanced
> parenthesis they would use the production:
>
> S -> (S)S | p
>
> where "|" means alternation and p is an epsilon or null production.
>
> In CUP one would specify the terminals and non-terminals, the precedence and
> then the grammar as above. But how does CUP understand the concept or
> meaning of a null production?

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