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From: Lars Schneider <larsxschneider@gmail.com>
To: Eric Sunshine <sunshine@sunshineco.com>
Cc: "Lars Schneider" <lars.schneider@autodesk.com>,
	"Git List" <git@vger.kernel.org>,
	"Junio C Hamano" <gitster@pobox.com>,
	"Torsten Bögershausen" <tboegi@web.de>,
	"Johannes Sixt" <j6t@kdbg.org>, "Jeff King" <peff@peff.net>,
	"Ramsay Jones" <ramsay@ramsayjones.plus.com>,
	"Johannes Schindelin" <Johannes.Schindelin@gmx.de>,
	"Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>
Subject: Re: [PATCH v12 04/10] utf8: teach same_encoding() alternative UTF encoding names
Date: Fri, 16 Mar 2018 00:35:03 +0100	[thread overview]
Message-ID: <328BE614-1927-450A-85D1-7391D0BB5C47@gmail.com> (raw)
In-Reply-To: <CAPig+cSvBi1pJYC-DND1_x9rHhmoAPs90B_3Fg53-X5FjtCQhA@mail.gmail.com>


> On 16 Mar 2018, at 00:25, Eric Sunshine <sunshine@sunshineco.com> wrote:
> 
> On Thu, Mar 15, 2018 at 6:57 PM,  <lars.schneider@autodesk.com> wrote:
>> The function same_encoding() checked only for alternative UTF-8 encoding
>> names. Teach it to check for all kinds of alternative UTF encoding
>> names.
>> 
>> Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
>> ---
>> diff --git a/utf8.c b/utf8.c
>> @@ -401,11 +401,27 @@ void strbuf_utf8_replace(struct strbuf *sb_src, int pos, int width,
>> +static int same_utf_encoding(const char *src, const char *dst)
>> +{
>> +       if (istarts_with(src, "utf") && istarts_with(dst, "utf")) {
>> +               /* src[3] or dst[3] might be '\0' */
>> +               int i = (src[3] == '-' ? 4 : 3);
>> +               int j = (dst[3] == '-' ? 4 : 3);
>> +               return !strcasecmp(src+i, dst+j);
>> +       }
>> +       return 0;
>> +}
> 
> Alternate implementation without magic numbers:
> 
>    if (iskip_prefix(src, "utf", &src) &&
>        iskip_prefix(dst, "utf", &dst)) {
>        if (*src == '-')
>            src++;
>        if (*dst == '-')
>            dst++;
>        return !strcasecmp(src, dst);
>    }
>    return 0;
> 
> ... assuming you add an iskip_prefix() function (patterned after skip_prefix()).

If a reroll is necessary, then I can do this.


>> int is_encoding_utf8(const char *name)
>> {
>>        if (!name)
>>                return 1;
>> -       if (!strcasecmp(name, "utf-8") || !strcasecmp(name, "utf8"))
>> +       if (same_utf_encoding("utf-8", name))
>>                return 1;
>>        return 0;
>> }
>> @@ -414,6 +430,8 @@ int same_encoding(const char *src, const char *dst)
>> {
>>        if (is_encoding_utf8(src) && is_encoding_utf8(dst))
>>                return 1;
>> +       if (same_utf_encoding(src, dst))
>> +               return 1;
>>        return !strcasecmp(src, dst);
>> }
> 
> This seems odd. I would have expected the newly-added generalized
> conditional to replace the original UTF-8-specific conditional, not
> supplement it. That is, shouldn't the entire function body be:
> 
>    if (same_utf_encoding(src, dst))
>        return 1;
>    return !strcasecmp(src, dst);

No, because is_encoding_utf8() returns "true" (=1) if the encoding
is NULL. That is not the case for UTF-16 et al. The caller of
same_encoding() might expect that behavior.

I could have moved the "UTF-8" == NULL assumption into 
same_utf_encoding() but that did not feel right.

Does this make sense?

- Lars

  reply	other threads:[~2018-03-15 23:35 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-15 22:57 [PATCH v12 00/10] convert: add support for different encodings lars.schneider
2018-03-15 22:57 ` [PATCH v12 01/10] strbuf: remove unnecessary NUL assignment in xstrdup_tolower() lars.schneider
2018-03-15 22:57 ` [PATCH v12 02/10] strbuf: add xstrdup_toupper() lars.schneider
2018-03-15 22:57 ` [PATCH v12 03/10] strbuf: add a case insensitive starts_with() lars.schneider
2018-03-16 17:33   ` Morten Welinder
2018-03-16 17:39     ` Junio C Hamano
2018-03-15 22:57 ` [PATCH v12 04/10] utf8: teach same_encoding() alternative UTF encoding names lars.schneider
2018-03-15 23:25   ` Eric Sunshine
2018-03-15 23:35     ` Lars Schneider [this message]
2018-03-15 23:54       ` Eric Sunshine
2018-03-16 17:50         ` Junio C Hamano
2018-03-16 18:19           ` Eric Sunshine
2018-04-01 14:18             ` Lars Schneider
2018-03-15 22:57 ` [PATCH v12 05/10] utf8: add function to detect prohibited UTF-16/32 BOM lars.schneider
2018-03-15 22:57 ` [PATCH v12 06/10] utf8: add function to detect a missing " lars.schneider
2018-03-15 22:57 ` [PATCH v12 07/10] convert: add 'working-tree-encoding' attribute lars.schneider
2018-03-15 22:57 ` [PATCH v12 08/10] convert: check for detectable errors in UTF encodings lars.schneider
2018-03-15 22:57 ` [PATCH v12 09/10] convert: add tracing for 'working-tree-encoding' attribute lars.schneider
2018-03-15 22:57 ` [PATCH v12 10/10] convert: add round trip check based on 'core.checkRoundtripEncoding' lars.schneider
2018-03-29 18:37 ` [PATCH v12 00/10] convert: add support for different encodings Junio C Hamano
2018-04-02 18:31   ` Lars Schneider
2018-04-03  8:37     ` Lars Schneider

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