From mboxrd@z Thu Jan  1 00:00:00 1970
From: Neil Jerram <neiljerram@gmail.com>
Subject: Re: [RFC] Fixing link encoding once and for all
Date: Tue, 5 Mar 2019 16:27:31 +0000
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To: Neil Jerram <neiljerram@gmail.com>, Org Mode List <emacs-orgmode@gnu.org>

Hi Nicolas,

On Tue, 5 Mar 2019 at 00:23, Nicolas Goaziou <mail@nicolasgoaziou.fr> wrote:
[...]
> So, the new challenger is:
>
>     "\\[\\[\\(\\(?:.\\|\n\\)*?[^\\]\\(\\\\\\\\\\)*\\)\\]\\(?:\\[\\(\\(?:.\\|\n\\)+?\\)\\]\\)?\\]"
>
> Beautiful.
>
> The commented rx equivalent would be:
>
> (seq "["
>      ;; URI part: match group 1.
>      "["
>      (group
>       (*? anything)
>       ;; Allow an even number of backslashes before the closing bracket.
>       (not (any "\\"))
>       (zero-or-more (group "\\\\")))
>      "]"
>      ;; Description (optional): match group 2.
>      (opt "[" (group (+? anything)) "]")
>      "]")
>
> > \(        # begin group 3
> > ?         # don't understand
> > :\[       # literal :[
>
> [...]
>
> > but there's at least a ? that I don't understand, and I'm afraid I'm
> > not seeing how it's useful.
>
> \(?: ... \) is a shy group.

Thanks for explaining that.  It's not mentioned in the manual though
(https://www.gnu.org/software/emacs/manual/html_node/emacs/Regexps.html);
are you sure that it's supported in Emacs regexps?

> > If you think it works, I'm happy to defer to your judgement on that!
> > Although I suggested the idea, I don't know Org nearly well enough to
> > be sure that I haven't missed problems;
>
> We are solving the problem with a regexp. What bad things could happen? ;)

Well hopefully the fallout is limited to destroying all of the text in
one Org buffer. :-)

More seriously, though, I don't understand when and how the regexp is
used.  Presumably you loop through the buffer looking for matches, but
what do you do after each match?

Regards,
    Neil