Re: [PATCH] userdiff: expand detected chunk headers for css

[Junio C Hamano <gitster@pobox.com>]

"Sohom Datta via GitGitGadget" <gitgitgadget@gmail.com> writes:

> From: Sohom <sohom.datta@learner.manipal.edu>
>
> Added support for classes, ids, :root selectors
> as well as @-based statements (ex: @page, @media
> and @keyframes ).
>
> Also added tests for the same.
>
> Signed-off-by: Sohom Datta <sohom.datta@learner.manipal.edu>
> ---
>     userdiff: Expand detected chunk headers for css
>     
>     Currently, the regex used for the CSS builtin diff driver in git is only
>     able to show chunk headers for lines that start with a number, a letter
>     or an underscore.
>     
>     However, the regex fails to detect classes (starts with a .), ids
>     (starts with a #), :root and attribute-value based selectors (for
>     example [class*="col-"]), as well as @based block-level statements like 
>     @page,@keyframes and @media since all of them, start with a special
>     character.

The above two would be much better beginning of the log message for
this change modulo a few nits.

 - We first explain what the current system does in the present
   tense.  "Currently, " at the beginning is a pure noise.

 - And we point out what may be lacking (which you did a very good
   job in the second paragraph).

 - And finally, we write in imperative mood to give an order to the
   codebase to "become like so." or an order to the patch monkey to
   "make the codebase like so."

As the last paragraph to follow the two paragraphs, something like

    Allow the selectors to begin with these special characters.

would be sufficient.

> -	 "^[_a-z0-9].*$",
> +	 "^(([_a-z0-9]|[:[@.#][_a-z0-9]).*)$",

As we seem to allow ? (i.e. zero or one) in the patterns, it probably
makes it easier to read to spell the above like this instead?

-	"^[_a-z0-9].*$",
+	"^[:[@.#]?[_a-z0-9].*$"