MIME-Version: 1.0
References: <55D6114D.4050100@clear.net.nz>
Content-Type: text/plain; charset=UTF-8
Message-ID:  <CANQYN6xYw_n5htc4OdhstpqNfLm3V4=cUEgaHYutz-KiSxAReg@mail.gmail.com>
Date:         Thu, 20 Aug 2015 02:05:00 +0200
Reply-To: Mailing list for the LaTeX3 project
              <LATEX-L@LISTSERV.UNI-HEIDELBERG.DE>
Sender: Mailing list for the LaTeX3 project <LATEX-L@LISTSERV.UNI-HEIDELBERG.DE>
From: Bruno Le Floch <blflatex@GMAIL.COM>
Subject: Re: peek functions
To: LATEX-L@LISTSERV.UNI-HEIDELBERG.DE
In-Reply-To:  <55D6114D.4050100@clear.net.nz>
Precedence: list
Envelope-To: <rainer.schoepf@GMX.NET>
Status: R

Hello,

> Can someone show me or point me to some code where the peek functions
> have been used (preferably in a straightforward way)? I'm thinking in
> particular of functions like \peek_charcode:NTF.

Two packages seem to use these peek functions a lot: mhchem and
pkgloader.  One thing I note is that both packages involve
constructions reminiscent of a case statement:

    \peek_charcode:NTF M
      {
        \mypkg_grab_M_and_do_something:n
      }
      {
        \peek_charcode:NTF C
          {
            \mypkg_grab_C_and_do_something:n
          }
          {
            \mypkg_something_else:
          }
      }

Such code may be simplified (and sped up a bit) if we provided a
\peek_case_charcode:NnTF function.  Is there interest for such an
additional function?

Actually, looking at mhchem a bit more, it seems that there is
probably room for simplification if we provided better tools for
parsing.  I'll think.

Regards,

Bruno