BNF questions and comments

[Jascha Wetzel]

0ffh wrote:
> BLS wrote:
>> What is the meaning of : epsilon ?
> 
> Usually this means nothing, erm, "nothing" in such a context.
> 
> Something like "a <- b / epsilon" is equivalent to "a <- b?".
> 
> Regards, Frank

yep, epsilon means, the production rule may produce nothing. in the 
seatd grammar, in most cases, non-terminals that have an epsilon rule, 
also have a name with suffix "Opt" for "optional".
note that epsilon rules are just a convenient shortcut:
EnumDeclaration -> "enum" EnumBaseTypeOpt EnumBody
may be rewritten as:
EnumDeclaration -> "enum" EnumBaseType EnumBody
EnumDeclaration -> "enum" EnumBody