Re: [gentoo-user] Query: any good venue for sample lex&yacc or flex&bison programs

[Etaoin Shrdlu]

On Tuesday 2 September 2008, 07:01, Kevin O'Gorman wrote:

> I've been teaching myself scanners over the summer, thinking to teach
> my students this fall.
>
> It was hard because just about all of the examples are inadequate for
> one of these reasons:
>    1 They are pure lex, or pure yacc, not a combination. Ditto flex
> and bison.  Most of such sample programs work okay, but they're not
> what's needed.  Getting the parser and scanner to work together is the
> key thing.
>    2 They are spotty in their coverage of features
>    3 They are incomplete and fail to compile as presented; the
> documentation is very old-style UNIX in general, and very hard to
> learn the necessary fixes from it.
>    4 They are old and fail on modern versions of the software
>    5 They are just plain broken
>
> This applies to examples in the texinfo pages, the 2003 O'Reilly book,
> and online manuals.
>
> This is a very serious problem for learning these tools in their
> combined form.  I'm relatively good at dealing with such stuff (having
> decades of practice), but I would not expect my undergrads to be able
> to learn with these materials.
>
> I was finally able to cobble together a working flex/bison parser from
> the bison-bridge example in an appendix to the flex info page.  I'd
> like to share it, and perhaps other _working_ sample programs to the
> web at large.  Does anyone know of a better venue for this than just
> some random page on my school's web server?  I would like other people
> to be able to find this stuff and perhaps add to it or otherwise
> improve on it.

When I had to study the subject, I found these documents (in addition to 
the dragon book, which was of course the primary source of information 
for the underlying theory):

http://epaperpress.com/lexandyacc/
http://www.kiv.zcu.cz/~lobaz/fjp/yacc/compiler_flex_bison.pdf
http://www.ibm.com/developerworks/linux/library/l-lexyac.html

The above documents all contain examples of using lex+yacc together to 
build an interpreter for simple languages, which is enough for an 
undergrad course imho. Also, I seem to remember that the flex and bison 
online manuals and the examples therein were quite accurate (but I might 
be wrong, it was some time ago).

I think a good place to discuss lex/yacc issues and get pointers to 
resources is the comp.compilers newsgroup, see 
http://compilers.iecc.com/index.phtml for more information, especially 
the FAQ section.

Another good place (maybe even better, since it's targeted to beginners) 
is the compilers 101 mailing list, see 
http://tech.groups.yahoo.com/group/compilers101/ for more information.