Article View: comp.lang.misc
Article #6377Re: Language Design, or: is C's Grammar Context Free
From: Rahul Dhesi
Date: Wed, 05 Apr 1989 16:41
Date: Wed, 05 Apr 1989 16:41
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In article <913@m10ux.ATT.COM> mnc@m10ux.ATT.COM (Michael Condict) writes:
>Consider the following in C, however:
>
> . . . { T (x); . . . }
>
>How should the construct be parsed?
The parsing is always the same, from the point of view of a
context-free grammer. It's the semantics that are different. That you
assign a different meaning to the language construct based on what has
come before has nothing to do with its context-free grammar.
Context-free grammars don't care about the declaration of type names.
If they could, they wouldn't be context-free.
The confusion here arises because real languages like Pascal and C
simply *cannot* be completely defined using context-free grammars. But
they are--because the definition we use is incomplete, and we fill in
the missing parts with a set of additional rules that are not part of
the context-free grammar. The size of this set of rules may or may not
be greater for C than for Pascal.
--
Rahul Dhesi UUCP: <backbones>!{iuvax,pur-ee}!bsu-cs!dhesi
ARPA: dhesi@bsu-cs.bsu.edu
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!bsu-cs!dhesi From: dhesi@bsu-cs.UUCP (Rahul Dhesi) Newsgroups: comp.lang.misc Subject: Re: Language Design, or: is C's Grammar Context Free Keywords: BNF, Grammars, Silliness Message-ID: <6541@bsu-cs.UUCP> Date: 5 Apr 89 16:41:06 GMT References: <5200040@m.cs.uiuc.edu> <12443@watdragon.waterloo.edu> <16559@mimsy.UUCP> <913@m10ux.ATT.COM> Reply-To: dhesi@bsu-cs.UUCP (Rahul Dhesi) Organization: CS Dept, Ball St U, Muncie, Indiana Lines: 24