From: Nathan Trapuzzano <nbtrap@nbtrap.com>
To: Eli Zaretskii <eliz@gnu.org>
Cc: 17130@debbugs.gnu.org
Subject: bug#17130: 24.4.50; Deficient Unicode case folding
Date: Sat, 29 Mar 2014 10:03:32 -0400 [thread overview]
Message-ID: <87eh1lcdaj.fsf@nbtrap.com> (raw)
In-Reply-To: <83d2h5du2e.fsf@gnu.org> (Eli Zaretskii's message of "Sat, 29 Mar 2014 16:15:53 +0300")
Eli Zaretskii <eliz@gnu.org> writes:
>> Reading through the manual section on case tables, it seems that this
>> could be supported via the extra "canonicalize" slot:
>>
>> CANONICALIZE
>> The canonicalize table maps all of a set of case-related
>> characters into a particular member of that set.
>
> Not efficiently, no. E.g., how will you find ς from σ, using this
> method?
σ, ς, and Σ would all have σ in the CANONICALIZE slot, since they all
fold to σ. (By the way, ς should upcase to Σ--that much I know the case
tables can handle.)
> Besides, don't we also need to know that ς can only be present at the
> end of a word?
Don't think so. AFAIK, Unicode says nothing about ordering except when
it comes to combining characters. But even it did prescribe such a
rule, I don't think it would have anything to do with case folding.
>> If this isn't already used for Unicode case folding, what _is_ it used
>> for?
>
> It is used for case-insensitive regexp matching, see search.c.
Right, but what I'm asking is: if Emacs doesn't do Unicode case folding,
what is the purpose of the CANONICALIZE slot except as a kind of
placeholder that gets autofilled? Are there other kinds of case
folding--other than traditional upper/lower and Unicode--that I'm not
aware of? I understand that Emacs autofills the CANONICALIZE slot from
the other slots, but only when the CANONICALIZE slot is not already set
to non-nil. What if the CANONICALIZE slot on ς were set to σ? I think
that's all that would have to happen for the Unicode folding to work.
It seems the machinery is already in place.
next prev parent reply other threads:[~2014-03-29 14:03 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-28 12:07 bug#17130: 24.4.50; Deficient Unicode case folding Nathan Trapuzzano
2014-03-28 15:51 ` Eli Zaretskii
2014-03-28 19:31 ` nbtrap
2014-03-29 6:45 ` Eli Zaretskii
[not found] ` <87ob0pnptc.fsf@nbtrap.com>
2014-03-29 13:15 ` Eli Zaretskii
2014-03-29 14:03 ` Nathan Trapuzzano [this message]
2014-03-29 14:45 ` Eli Zaretskii
2014-03-29 15:29 ` Nathan Trapuzzano
2014-03-29 17:37 ` Eli Zaretskii
2014-03-29 18:31 ` Nathan Trapuzzano
2014-03-29 18:36 ` Nathan Trapuzzano
2014-03-29 19:51 ` Eli Zaretskii
2014-03-29 20:15 ` Nathan Trapuzzano
2014-03-30 2:45 ` Eli Zaretskii
2014-03-29 19:50 ` Eli Zaretskii
2014-03-29 20:01 ` Nathan Trapuzzano
2019-09-29 14:23 ` Lars Ingebrigtsen
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