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From: Atharva Raykar <raykar.ath@gmail.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: git@vger.kernel.org
Subject: Re: [GSOC][PATCH] userdiff: add support for Scheme
Date: Mon, 29 Mar 2021 13:42:22 +0530	[thread overview]
Message-ID: <562DCDA0-EAE6-408F-97D7-127689DE5559@gmail.com> (raw)
In-Reply-To: <xmqqft0fm9uu.fsf@gitster.g>

On 28-Mar-2021, at 23:36, Junio C Hamano <gitster@pobox.com> wrote:
> 
> Atharva Raykar <raykar.ath@gmail.com> writes:
> 
>>>> +         "(\\.|[^][)(\\}\\{ ])+"),
>>> 
>>> One or more "dot or anything other than SP or parentheses"?  But
>>> a dot "." is neither a space or any {bra-ce} letter, so would the
>>> above be equivalent to
>>> 
>>> 	"[^][()\\{\\} \t]+"
>>> 
>>> I wonder...
>> 
>> A backslash is allowed in scheme identifiers, and I erroneously thought that
>> the first part handles the case for identifiers such as `component\new` or 
>> `\"id-with-quotes\"`. (I tested it with a regex engine that behaves differently
>> than the one git is using, my bad.)
> 
> Ah, perhaps you didn't have enough backslashes.  A half of the
> doubled one before the dot is eaten by the C compiler, so the regexp
> engine is seeing only a single backslash before the dot, which means
> "literally a single dot".  If you meant "literally a single
> backslash, followed by any single char", you probably would write 4
> backslashes and a dot---half of the backslashes would be eaten by
> the compiler, so you'd be passing two backslashes and a dot, which
> is probably what you meant.
> 
> Having said that, two further points.
> 
> - the "anything but whitespaces and various forms of parentheses"
>   set would include backslash, so 'component\new' would be taken as
>   a single word with "[^][()\\{\\} \t]+", wouldn't it?
> 
> - how common is the use of backslashes in identifiers?  I am trying
>   to see if the additional complexity needed to support them is
>   worth the benefit.

I have refined the regex, and now it is much simpler and does all of what
I want it to:

	"([^][)(}{[:space:]])+"

I did not have to escape the various parentheses, so I avoided the need to
handle backslashes separately. The "\\t" was causing problems as well because
it took it as a '\' followed by a 't' (Thanks to j416 on #git-devel for
helping me out on this).

>> Yes, this is exactly what I was trying to express. All words should be
>> delimited by either whitespace or a parenthesis, and all other special
>> characters should be accepted as part of the word.
> 
> That sentence after "All words should be..." would be a good comment
> to replace what you wrote in the original, then ;-).

Yes, that should make it a lot more clear.


  reply	other threads:[~2021-03-29  8:14 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-27 17:39 [GSOC][PATCH] userdiff: add support for Scheme Atharva Raykar
2021-03-27 22:50 ` Junio C Hamano
2021-03-27 23:09   ` Junio C Hamano
2021-03-28  3:16     ` Ævar Arnfjörð Bjarmason
2021-03-28  5:37       ` Junio C Hamano
2021-03-28 12:40       ` Atharva Raykar
2021-03-29 10:08         ` Phillip Wood
2021-03-30  6:41           ` Atharva Raykar
2021-03-30 12:56             ` Ævar Arnfjörð Bjarmason
2021-03-30 13:48               ` Atharva Raykar
2021-03-28 12:45     ` Atharva Raykar
2021-03-28 11:51   ` Atharva Raykar
2021-03-28 18:06     ` Junio C Hamano
2021-03-29  8:12       ` Atharva Raykar [this message]
2021-03-29 20:47         ` Junio C Hamano
2021-03-29 10:12     ` Phillip Wood
2021-03-27 23:46 ` Johannes Sixt
2021-03-28 12:23   ` Atharva Raykar
2021-03-29 10:18     ` Phillip Wood
2021-03-29 10:48       ` Johannes Sixt
2021-03-29 13:12         ` Ævar Arnfjörð Bjarmason
2021-03-29 14:06           ` Phillip Wood
2021-03-30  7:04       ` Atharva Raykar
2021-03-30 10:22         ` Atharva Raykar
2021-04-05 10:04           ` Phillip Wood
2021-04-05 17:58             ` Johannes Sixt
2021-04-06 12:29             ` Atharva Raykar
2021-04-06 19:10               ` Phillip Wood
2021-04-03 13:16 ` [GSoC][PATCH v2 0/1] userdiff: add support for scheme Atharva Raykar
2021-04-03 13:16   ` [GSoC][PATCH v2 1/1] " Atharva Raykar
2021-04-05 10:21     ` Phillip Wood
2021-04-06 10:32       ` Atharva Raykar
2021-04-08  9:14   ` [GSoC][PATCH v3 0/1] " Atharva Raykar
2021-04-08  9:14   ` [GSoC][PATCH v3 1/1] userdiff: add support for Scheme Atharva Raykar
2021-04-12 23:04     ` Junio C Hamano

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