From: Charles Mills <cmills@...>
Date: 2005-03-17T00:34:48+09:00
Subject: Re: Examples for racc?


Ben Giddings wrote:
> Hey all,
>
> I was trying to use racc the other day, and couldn't get even the
most
> basic sample started.  Does anybody know of any fully working sample
> grammar files for it?

See below.
>
> The calculator that is mentioned in the docs would be fine, if it had

> the next_token, on_error and parse implemented.  My main problem is
that
> I'm not sure what legal values next_token can return.
>
Depends on your grammer, but a token should be a two element array,
whose first element describes the type of the token (usually a symbol -
like :IDENTIFIER) and the second element is the value of the token
(usually a string - like 'x').  Any token whose type (first element) is
false signals end of input.
You should write next_token() so it always returns [false, false]
(second element could be anything) when end of input is reached.  (If
next_token() returns nil you will cause RACC to raise an error.)

> It would be great if there was some fully-working sample code along
with
> the docs, instead of just the example snippets.  I even tried
> understanding some of the japanese results that google found, but to
no
> avail.
>
There is a link on my website (http://cmills.freeshell.org/) to a
presentation I gave at the PDX user group on RACC.  It includes a power
point presentation on RACC and a bunch of small working example
programs - the grammer for some is only a few lines long.

-Charlie