220 26391 <7f783407-0c3c-4381-a852-dfd12bc450d1@isocpp.org> article Path: news.gmane.org!not-for-mail From: Nicol Bolas Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: iswalpha and locales Date: Sat, 25 Jun 2016 12:09:46 -0700 (PDT) Lines: 106 Approved: news@gmane.org Message-ID: <7f783407-0c3c-4381-a852-dfd12bc450d1@isocpp.org> References: <5057e854-b2ea-4c39-81c7-367bc3e54080@isocpp.org> <5458114.SXJFP9uSZR@tjmaciei-mobl1> <7091420.GCog6ZeHg6@tjmaciei-mobl1> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_740_642100542.1466881786831" X-Trace: ger.gmane.org 1466881797 11648 80.91.229.3 (25 Jun 2016 19:09:57 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 25 Jun 2016 19:09:57 +0000 (UTC) Cc: asorenji@gmail.com To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCEKFTV6ZUMBB65NXO5QKGQEBYY4VQY@isocpp.org Sat Jun 25 21:09:53 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-oi0-f72.google.com ([209.85.218.72]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1bGsxh-0005Qy-K5 for gclcip-std-proposals@m.gmane.org; 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Sat, 25 Jun 2016 12:09:48 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.107.14.6 with SMTP id 6ls3465303ioo.14.gmail; Sat, 25 Jun 2016 12:09:47 -0700 (PDT) X-Received: by 10.36.242.65 with SMTP id j62mr113163ith.8.1466881787723; Sat, 25 Jun 2016 12:09:47 -0700 (PDT) In-Reply-To: X-Original-Sender: jmckesson@gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:26391 Archived-At: ------=_Part_740_642100542.1466881786831 Content-Type: multipart/alternative; boundary="----=_Part_741_1977422704.1466881786836" ------=_Part_741_1977422704.1466881786836 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Saturday, June 25, 2016 at 2:50:32 PM UTC-4, Aso Renji wrote: > > Thiago Macieira > =D0=BF=D0=B8=D1=81=D0= =B0=D0=BB(=D0=B0) =D0=B2 =D1=81=D0=B2=D0=BE=D1=91=D0=BC=20 > =D0=BF=D0=B8=D1=81=D1=8C=D0=BC=D0=B5 Sat, 25 Jun =20 > 2016 21:39:10 +0300:=20 > > > You should use char16_t and char32_t to be sure to have Unicode.=20 > But iswalpha with char16_t argument don't exist. In this case I'm change = =20 > proposal to adding isalpha version for utf16/utf32 characters. For exampl= e=20 > =20 > - isu16alpha.=20 > Here's the problem with that. Unicode has very complex rules about what=20 constitutes an "alphabetic" character. Indeed, it has a large list; for=20 every codepoint it defines, it says if that codepoint is alphabetic or not.= =20 So too for many other questions like `isupper` and so forth. That's a lot of tables to be including. I believe that the table can be=20 compacted via clever programming to be of reasonable length. But that would= =20 require a good implementation to prove it. Also, such functions cannot be applied to a `char16_t`, becuase a=20 `char16_t` is not a Unicode codepoint. It is only a UTF-16 code unit, which= =20 may be a valid codepoint or it may be a surrogate pair for a valid=20 codepoint, in accord with the UTF-16 encoding rules. --=20 You received this message because you are subscribed to the Google Groups "= ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. To view this discussion on the web visit https://groups.google.com/a/isocpp= ..org/d/msgid/std-proposals/7f783407-0c3c-4381-a852-dfd12bc450d1%40isocpp.or= g. ------=_Part_741_1977422704.1466881786836 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable


On Saturday, June 25, 2016 at 2:50:32 PM UTC-4, As= o Renji wrote:
Thiago Macieira = <t= hi...@macieira.org> =D0=BF=D0=B8=D1=81=D0=B0=D0=BB(=D0=B0) =D0=B2 = =D1=81=D0=B2=D0=BE=D1=91=D0=BC =D0=BF=D0=B8=D1=81=D1=8C=D0=BC=D0=B5 Sat, 25= Jun =C2=A0
2016 21:39:10 +0300:

> You should use char16_t and char32_t to be sure to have Unicode.
But iswalpha with char16_t argument don't exist. In this case I'= ;m change =C2=A0
proposal to adding isalpha version for utf16/utf32 characters. For exam= ple =C2=A0
- isu16alpha.

Here's the problem with that. Unicode has ver= y complex rules about what constitutes an "alphabetic" character.= Indeed, it has a large list; for every codepoint it defines, it says if th= at codepoint is alphabetic or not. So too for many other questions like `is= upper` and so forth.

That's a lot of tables to be including. I b= elieve that the table can be compacted via clever programming to be of reas= onable length. But that would require a good implementation to prove it.
Also, such functions cannot be applied to a `char16_t`, becuase a `cha= r16_t` is not a Unicode codepoint. It is only a UTF-16 code unit, which may= be a valid codepoint or it may be a surrogate pair for a valid codepoint, = in accord with the UTF-16 encoding rules.

--
You received this message because you are subscribed to the Google Groups &= quot;ISO C++ Standard - Future Proposals" group.
To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposa= ls+unsubscribe@isocpp.org.
To post to this group, send email to std-proposals@isocpp.org.
To view this discussion on the web visit https://groups.google.= com/a/isocpp.org/d/msgid/std-proposals/7f783407-0c3c-4381-a852-dfd12bc450d1= %40isocpp.org.
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