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From: rfg@ics.uci.edu (Ronald Guilmette)
Newsgroups: comp.lang.c++
Subject: Re: zortech problem with lex
Message-ID: <25F8C92A.9349@paris.ics.uci.edu>
Date: 10 Mar 90 09:30:18 GMT
References: <6300008@ux1.cso.uiuc.edu> <24800002@sunb6> <25ECE752.29589@paris.ics.uci.edu> <10541@alice.UUCP> <6553@cadillac.CAD.MCC.COM>
Reply-To: rfg@ics.uci.edu (Ronald Guilmette)
Organization: UC Irvine Department of ICS
Lines: 26

In article <6553@cadillac.CAD.MCC.COM> ned@MCC.COM (Ned Nowotny) writes:
>
>Given the imprecise nature of the C++ specification, I am more than a
>little disappointed that the language does not have a grammar expressible
>in BNF form that will accept all legal strings and reject all illegal
>strings.

As Joe English also points out, this is utter nonsense.  In all of the
useful languages that I know of, the correctness of statements is based
upon both syntax *and* semantics.  Neither one can be used in isolation
to decide on the correctness of statements.

>... While it may be
>true that some LALR(1) grammar will accept all legal C++ strings, the fact
>that the grammar must also accept illegal strings makes the claim that
>C++ is somehow a LALR(1) language something less than useful.

I agree that in practice, nobody actually is stupid enough to use V* as their
LALR(1) grammar for parsing C++ or other languages, but just because the
statement "C++ is LALR(1)" may not be "useful" does not mean that it is
not 100% accurate.  In fact, I believe that it is.


// Ron Guilmette (rfg@ics.uci.edu)
// C++ Entomologist
// Motto:  If it sticks, force it.  If it breaks, it needed replacing anyway.