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bug#17130: 24.4.50; Deficient Unicode case folding
From: |
Nathan Trapuzzano |
Subject: |
bug#17130: 24.4.50; Deficient Unicode case folding |
Date: |
Sat, 29 Mar 2014 10:03:32 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.4.50 (gnu/linux) |
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.
- bug#17130: 24.4.50; Deficient Unicode case folding, Nathan Trapuzzano, 2014/03/28
- bug#17130: 24.4.50; Deficient Unicode case folding, Eli Zaretskii, 2014/03/28
- bug#17130: 24.4.50; Deficient Unicode case folding, nbtrap, 2014/03/28
- bug#17130: 24.4.50; Deficient Unicode case folding, Eli Zaretskii, 2014/03/29
- bug#17130: 24.4.50; Deficient Unicode case folding, Nathan Trapuzzano, 2014/03/29
- bug#17130: 24.4.50; Deficient Unicode case folding, Eli Zaretskii, 2014/03/29
- bug#17130: 24.4.50; Deficient Unicode case folding,
Nathan Trapuzzano <=
- bug#17130: 24.4.50; Deficient Unicode case folding, Eli Zaretskii, 2014/03/29
- bug#17130: 24.4.50; Deficient Unicode case folding, Nathan Trapuzzano, 2014/03/29
- bug#17130: 24.4.50; Deficient Unicode case folding, Eli Zaretskii, 2014/03/29
- bug#17130: 24.4.50; Deficient Unicode case folding, Nathan Trapuzzano, 2014/03/29
- bug#17130: 24.4.50; Deficient Unicode case folding, Nathan Trapuzzano, 2014/03/29
- bug#17130: 24.4.50; Deficient Unicode case folding, Eli Zaretskii, 2014/03/29
- bug#17130: 24.4.50; Deficient Unicode case folding, Nathan Trapuzzano, 2014/03/29
- bug#17130: 24.4.50; Deficient Unicode case folding, Eli Zaretskii, 2014/03/29
- bug#17130: 24.4.50; Deficient Unicode case folding, Eli Zaretskii, 2014/03/29
- bug#17130: 24.4.50; Deficient Unicode case folding, Nathan Trapuzzano, 2014/03/29