From:	"Christopher Nelson" <paradox AT gye DOT satnet DOT net>
To:	<djgpp AT delorie DOT com>
Subject:	Re: Bison Vs. Flex?
Date:	Wed, 9 Jun 1999 10:28:35 -0600
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Reply-To:	djgpp AT delorie DOT com

>What is the difference between Bison And Flex? (for djgpp).  I know That
>flex can make compilers for languages, but what about bison.  is it a
>parser?  Can I use one of these to parse thru a script language(that I
>made) without having to program the 'if', 'else', 'then', ect?  and
>without programming the variable interaction, like assign and make
>variables?



they're complimentary.  Flex is a lexical analysis tool, and Bison is a
parser generator.

Flex examines a stream of characters for a set that matches it's input
constraints, e.g., say you want a token that looks like this:  'if', Flex
would search the stream for that token.

Then, inside Bison, you could have a state that needs the token 'if', but
you call it tIF in Bison. in other words:

Flex's command would be:

if    return(tIF);

and Bison's would be:

ifstatement:    tIF '(' tEXPRESSION ')' block        { /* this is the action
that Bison performs if it matches all those tokens. */ }
        ;

    -={C}=-

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