Re: bison/flex grammar

"Pete Jinks" <pjj@cs.man.ac.uk>
8 Sep 2002 22:53:55 -0400

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Related articles
bison/flex grammar chvist@club-internet.fr (christian visticot) (2002-09-03)
Re: bison/flex grammar robert.f.monroe@verizon.net (Robert Monroe) (2002-09-08)
Re: bison/flex grammar pjj@cs.man.ac.uk (Pete Jinks) (2002-09-08)
Re: bison/flex grammar robert.f.monroe@verizon.net (Robert Monroe) (2002-09-11)
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From: "Pete Jinks" <pjj@cs.man.ac.uk>
Newsgroups: comp.compilers
Date: 8 Sep 2002 22:53:55 -0400
Organization: Computer Science Dept, University of Manchester
References: 02-09-020
Keywords: parse, lex
Posted-Date: 08 Sep 2002 22:53:55 EDT

christian visticot wrote:
>
> I try to parse a file like following:
>
> description=a super example keywords=value1 value2
>
> and the result would be:
>
> attribute:description
> values:a super example
>
> attribute keywords
> values: value1 value2


The flex:


[a-z]+"="[a-z0-9 ]+/[ \t\n] {char*c= strchr(yytext, '=');
                                                                  *c= 0; printf("attribute: %s\n", yytext);
                                                                  printf("values: %s\n\n", c+1);
                                                                }
[ \t\n] ;
. {printf("didn't recognise: %s\n", yytext);}


outputs:


attribute: description
values: a super example


attribute: keywords
values: value1 value2


which should give you some idea how to do it properly.
i.e. I wouldn't show this to my students, and what I would show them
would depend on the context in which I was solving this sub-problem.


--
Peter J. Jinks, Room 2.99, Department of Computer Science,
University of Manchester, Oxford Road, Manchester, M13 9PL, U.K.
(+44/0)161-275 6186 http://www.cs.man.ac.uk/~pjj


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