Re: Compilers construction tools questions

collins@cs.wm.edu (Bob Collins)
24 Jun 1998 10:56:40 -0400

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Compilers construction tools questions scavadini@hotmail.com (Salvador Valerio Cavadini) (1998-06-24)
Re: Compilers construction tools questions collins@cs.wm.edu (1998-06-24)
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From: collins@cs.wm.edu (Bob Collins)
Newsgroups: comp.compilers
Date: 24 Jun 1998 10:56:40 -0400
Organization: College of William & Mary
References: 98-06-138
Keywords: syntax, comment

"Salvador Valerio Cavadini" <scavadini@hotmail.com> wrote:
> 3- I downloaded the Ada grammar from comp.compilers file repository.
> This grammar uses a notation that I didn't see before.
> Example:
> NT : /* empty */
> | ..NT.. NT
> ;
>
> What means the two point ("..") before and after NT? The grammar
> documentation sais that is a "Yacckeable" version of EBNF. It is? The
> original Yacc accept EBNF? I compiled the grammar with diferent Yacc
> versions, most returned an error, others (included original Yacc)
> compiles but I noted that they not "understand" ..NT.. like EBNF.

An entry like
            NT1 : ..NT2.. NT3;
means zero or more instances of NT2.

An entry (with three dots) like
            NT1 : NT2 ...NT3..;
means zero or more instances of
            , NT3

--
Bob Collins <mailto:collins@cs.wm.edu> <http://ratbert.cs.wm.edu>
[Why did they invent yet another EBNF? -John]
--

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