Re: [PATCH 3/3] gitweb: Link to "git describe"'d commits in log messages

From: Jakub Narębski <jnareb@gmail.com>
Date: Sep 21, 2016, 19:13 UTC
Message-ID: <f6cceb0a-9224-70ef-4592-ce34fe8704fd@gmail.com>
In-Reply-To: <CACBZZX5QF7FztmU-mqOEx40kC-PpQ9SqcL8+3HtuntcRZ1tWzA@mail.gmail.com>

W dniu 21.09.2016 o 19:58, Ævar Arnfjörð Bjarmason pisze:

> On Wed, Sep 21, 2016 at 7:09 PM, Jakub Narębski <jnareb@gmail.com> wrote:
>> W dniu 21.09.2016 o 13:44, Ævar Arnfjörð Bjarmason napisał:

Show 20 quoted lines

>>> +            (?<!-) # see strbuf_check_tag_ref(). Tags can't start with -
>>> +            [A-Za-z0-9.-]+
>>> +            (?!\.) # refs can't end with ".", see check_refname_format()
>>
>> If we can assume that tag name is at least two characters (instead of
>> at least one character), we could get rid of those extended regexp
>> lookaround assertions:
>>
>>   (?<!pattern) - zero-width negative lookbehind assertion
>>   (?!pattern)  - zero-width negative lookahead  assertion
>>
>> That is:
>>
>>   +            [A-Za-z0-9.]   # see strbuf_check_tag_ref(). Tags can't start with -
>>   +            [A-Za-z0-9.-]*
>>   +            [A-Za-z0-9-]   # refs can't end with ".", see check_refname_format()
> 
> Why get rid of them? I'm all for improving the regex, there's bound to
> be lots of bugs in it, but since it's perl we can freely use its
> extended features.

Ah, all right. I was wondering how zero width assertions / patterns interact with each other, but zero-width negative lookaround assertions are really quite simple.

Show 6 quoted lines

> 
>> Also, the canonical documentation for what is allowed in refnames
>> is git-check-ref-format(1)... though it does not look like it includes
>> "tags cannot start with '-'".
> 
> Yeah, looks like that manpage needs to be patched.

Right.

> 
>> Anyway, perhaps 'is it valid refname' could be passed to a subroutine,
>> or a named regexp (which might be more involved, like disallowing two
>> consecutive dots, e.g. "(?!.*\.{2})" at beginning).

I wonder if rules for valid tag name can be described in extended regexp, and if it is, how readable would it be.

Regards,

-- 
Jakub Narębski