Re: yacc to BNF anyone (Virendra Kumar Mehta)
Fri, 23 Jul 1993 10:08:56 GMT

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yacc to BNF anyone (1993-07-22)
Re: yacc to BNF anyone (1993-07-23)
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Newsgroups: comp.compilers
From: (Virendra Kumar Mehta)
Keywords: yacc
Organization: Compilers Central
References: 93-07-069
Date: Fri, 23 Jul 1993 10:08:56 GMT

> Does anyone know of any tool/program/hack etc that given
> a yacc file will extract the bnf grammar ???

I guess you want the '.y' file with only the rules and not the actions.
John's solution of using the '.output' file with a script will be good
enough in that case.

In case you do not have Berkeley yacc, most yacc implementations store the
rules in the '.tab.c' file as an array of strings (which they use later to
print messages if YYDEBUG is set). You could extract this array and just
replace ':' to '::=' again, or whatever form you want it in.

(If nothing else works, use the brute force approach. A vi macro that
mathces a '{' and deletes till the matching '}' worked for me once.)


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