Re: [PATCH] userdiff: add built-in pattern for CSS

> CSS is widely used, motivating it being included as a built-in pattern.
>
> It must be noted that the word_regex for CSS (i.e. the regex defining
> what is a word in the language) does not consider '.' and '#' characters
> (in CSS selectors) to be part of the word. This behavior is documented
> by the test t/t4018/css-rule.
> The logic behind this behavior is the following: identifiers in CSS
> selectors are identifiers in a HTML/XML document. Therefore, the '.'/'#'
> character are not part of the identifier, but an indicator of the nature
> of the identifier in HTML/XML (class or id). Diffing ".class1" and
> ".class2" must show that the class name is changed, but we still are
> selecting a class.
>
> Logic behind the "pattern" regex is:
>      1. reject lines ending with a colon/semicolon (properties)
>      2. if a line begins with a name in column 1, pick the whole line
>
> Credits to Johannes Sixt (j6t@kdbg.org) for the pattern regex and most
> of the tests.
>
> Signed-off-by: William Duclot <william.duclot@ensimag.grenoble-inp.fr>
> Signed-off-by: Matthieu Moy <matthieu.moy@grenoble-inp.fr>
> ---
> Changes since V3:
>      - Add a few tests
>      - Remove a redondant test
>      - Handle trailing spaces
>      - Reword in doc
>      - Improvement of the pattern regex