[cl-ppcre-devel] Re: An idea for ppcre::register-groups-bind

[Edi Weitz]

Hi!

Sorry for the delay, I was on vacation.

Oh, and please use the mailing list - see Cc.

On Sat, 3 Jun 2006 22:28:29 +0200, "Alexander Kjeldaas" <alexander.kjeldaas at gmail.com> wrote:

> I'm a big fan of register-groups-bind.  For some longer texts that
> I'm parsing, I have code that looks like this:
>
> The idiom is - you want to go through the text matching various
> regexps, but you want to keep on to the end-position in order to do
> incremental matching.  So I added an :end-holder keyword parameter
> that is the name of a variable that is set to the end-match (I also
> added :start-holder, but I don't use it).
>
> To me, this type of parsing is relatively simple to debug, but it is
> also not too sloppy in that we don't start from the beginning all
> the time.
>
> :end-place and :start-place might be better names, I don't know..

I think that the idea is basically OK, but I'm not sure if I like that
seemingly END-POS is supposed to be an existing variable which is set
- I think it'd be more Lisp-y to bind within the body of the form.
Admittedly, the indentation would get quite nasty then.

Cheers,
Edi.

> (defun parse-stuff (string)
>   "Parse various account information"
>   (let ((result nil)
>         end-pos)
>     (register-groups-bind (foo)
>         ("Kontoinformasjon for (.*)\\s+" string :end-holder end-pos)
>       (push `(:username ,foo) result))
>     (register-groups-bind (foo)
>         ("Navn:[ \\t]+(.*)\\s+" string :start end-pos :end-holder end-pos)
>       (push `(:name ,foo) result))
>     ;; Use (?=Telefon) to not affect the end-position.
>     (register-groups-bind (addr1 addr2 addr3)
>         ("Adresse:[
> \\t]+(.*)\\s+(?:(.*)\\s+)?(?:(.*)\\s+)?(?=Telefon)" string :start
> end-pos :end-holder end-pos)
>       (push (remove-if-not #'identity `(:address ,addr1 ,addr2 ,addr3)) result))
>     (register-groups-bind (foo)
>         ("Telefon:[ \\t]+(\\+?\\d+)" string :start end-pos :end-holder end-pos)
>       (push `(:phone ,foo) result))
>     (register-groups-bind (foo)
>         ("Mobil:[ \\t]+(\\+?\\d+)" string :start end-pos :end-holder end-pos)
>       (push `(:mobile-phone ,foo) result))
>     (register-groups-bind (foo)
>         ("Epost:[ \\t]+(.*)\\n" string :start end-pos :end-holder end-pos)
>       (push `(:email ,foo) result))
>     (register-groups-bind (foo)
>         ("Epost:[ \\t]+(.*)\\n" string :start end-pos :end-holder end-pos)
>       (push `(:email ,foo) result))
>     (nreverse result)))