Re: hierarchical_identifier

From: Dennis Marsa (drm@xilinx.com)
Date: Fri Jan 31 2003 - 08:28:52 PST

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Shalom.Bresticker@motorola.com wrote:
> 
> All you have done here is replace unsigned_number with constant_expression,
> correct? (And reminded me that . should be ".").
> 
> That is a separate change, which I deliberately did not add here.
> It seems to be orthogonal to my change.
> I will relate separately to the SV-BC issue.
> 
> The big question I had, and I deliberately did not ask it explicitly at first,
> is: Is there a problem with a syntax definition which looks like "{a} b", where
> the multiple optional a precedes the obligatory b?

    > > >         {identifier ["["unsigned_number"]"] .} identifier

    For the purposes of the BNF, I think this is OK.

    However, looking at this again, this definition requires that a
hierarchical_identifier end with an identifier.  That is, it cannot
end with an index operation: a.b[1].

    The current set of rules for hierarchical_identifier seem to allow it
to end with an index operation.

    I'm not sure if this is important or not.

    If hierarchical_identifier should be allowed to end with an index
operation, the rule could be:

      hierarchical_identifier ::=
      identifier [ "[" unsigned_number "]" ] { "." identifier [ "[" unsigned_number "]" ] }

    Dennis

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