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[Emacs-peg-devel] Re: Experimenting with peg.el

From: Sebastian Tennant
Subject: [Emacs-peg-devel] Re: Experimenting with peg.el
Date: Mon, 26 Jan 2009 20:29:44 +0000
User-agent: Gnus/5.110011 (No Gnus v0.11) Emacs/22.2 (gnu/linux)

Quoth Helmut Eller <address@hidden>:
> Sebastian Tennant [2009-01-19 15:25+0100] writes:
>> This returns nil, but point does at least advance to the end of the
>> alias definition.
> nil as return value means that some rule failed to match.  In the
> example, command will consume everything so that nothing is left for the
> closing quot-mark.  You could use something like this:
> (defun peg-parse-alias ()
>   (peg-parse 
>    (definition 
>      (substring keyword)
>      ws name equals-sign quot-mark 
>      (substring command)
>      quot-mark)
>    (keyword "alias")
>    (ws (* (or " " "\t")))
>    (name (+ [a-z]))
>    (equals-sign "=")
>    (quot-mark (or "\"" "'"))
>    (command (+ (not quot-mark) (any)))
>    ))
> Note the new rule for command.  The (not quot-mark) ensures that
> quote-mark can match afterwards.  This (+ (not FOO) (any)) is the
> typical idiom for consuming everything upto the first FOO.

Thanks a lot Helmut.  It's quite clear to me now.  I hadn't grasped the
use of 'substring' either.  I'll work on the stack action soon (and I'm
bound to have some questions when I do).

> If you don't mind you can post questions [to the mailing list] to
> preserve them for the public.

Of course.  I subscribed (using the link you provided) about 20 mins ago
and still hadn't received a confirmation email.  Then it occurred to me
that you might have decided to dispense with confirmation emails


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