From: Mike Gran <spk121@yahoo.com>
To: Mark H Weaver <mhw@netris.org>,
"guile-devel@gnu.org" <guile-devel@gnu.org>
Subject: Re: uc_tolower (uc_toupper (x))
Date: Thu, 10 Mar 2011 16:54:41 -0800 (PST) [thread overview]
Message-ID: <486722.32491.qm@web37905.mail.mud.yahoo.com> (raw)
> From:Mark H Weaver <mhw@netris.org>
> To:guile-devel@gnu.org
> Cc:
> Sent:Thursday, March 10, 2011 3:39 PM
> Subject:uc_tolower (uc_toupper (x))
>
> I've noticed that srfi-13.c very frequently does:
>
> uc_tolower (uc_toupper (x))
>
> Is there a good reason to do this instead of:
>
> uc_tolower (x)
Unicode defines a case folding algorithm as well as
a data table for case insensitive sorting. Setting
things to lowercase is a decent approximation of
case folding. But doing the upper->lower operation picks
up a few more of the corner cases, like U+03C2 GREEK
SMALL LETTER FINAL SIGMA and U+03C3 GREEK SMALL LETTER SIGMA
which are the same letter with different representations,
or U+00B5 MICRO SIGN and U+039C GREEK SMALL LETTER MU
which are supposed to have the same sort ordering.
Now that we've pulled in all of libunistring, it might
be a good idea to see if it has a complete implementation
of unicode case folding, because upper->lower is also not
completely correct.
-Mike
next reply other threads:[~2011-03-11 0:54 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-11 0:54 Mike Gran [this message]
2011-03-11 22:33 ` Using libunistring for string comparisons et al Mark H Weaver
2011-03-11 22:36 ` Mark H Weaver
2011-03-11 23:09 ` Mark H Weaver
2011-03-12 13:46 ` Ludovic Courtès
2011-03-12 17:28 ` Mark H Weaver
2011-03-13 21:30 ` Ludovic Courtès
2011-03-30 9:05 ` Andy Wingo
2011-03-13 4:05 ` O(1) accessors for UTF-8 backed strings Mark H Weaver
2011-03-13 4:42 ` Alex Shinn
2011-03-15 15:46 ` Mark H Weaver
2011-03-16 0:07 ` Alex Shinn
2011-03-19 13:02 ` Andy Wingo
2011-03-30 9:20 ` Andy Wingo
2011-03-30 9:03 ` Using libunistring for string comparisons et al Andy Wingo
2011-03-31 14:19 ` Ludovic Courtès
2011-03-12 13:36 ` Ludovic Courtès
-- strict thread matches above, loose matches on Subject: below --
2011-03-10 23:39 uc_tolower (uc_toupper (x)) Mark H Weaver
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