Use "\/\*(.|\n)*?\*\/" with replace-regexp-in-string
reddit / emacs

----------------------------------------------------------------------
ShadowRylander · 2022-02-08 22:02

Hello!

I'd like to remove comments in a [minified css stylesheet](https://git
hub.com/shadowrylander/settings/blob/main/src/styles/highlight/gruvbox
-dark-hard.css), and to do so, I'm curling the stylesheet and trying
to regex replace the comments with `\/\*(.|\n)*?\*\/`; however, while
it works with a regex tester, it doesn't work in `replace-regexp-in-
string`. I've noticed that I have to escape the `\*`, the brackets,
and the newline character, but is there any way to escape whatever is
needed, without me having to remember to translate a regular regexp to
an elisp regexp?

Thank you kindly for the help!

----------------------------------------------------------------------
SlowValue · 2022-02-09 07:47

It is possible.

I would use `M-x re-builder` to do that.
In re-builder, first switch it to `string` syntax mode (`M-x reb-
change-syntax <RET> string <RET>`. Then paste your regexp between
those `"`. Next switch to `read` syntax mode.

A good thing with `re-builder` is, that you can see if your regexp
matches in the buffer.

`re-builder` is also able to handle Perl style regexps and `rx` style
regexps, if you install some packages.

----------------------------------------------------------------------
7890yuiop · 2022-02-09 09:06

> ... a regex tester

What regexp tester?  Did it use the Emacs dialect of regexps?  [No, we
can see that it did not.]  You can't use any arbitrary regexp tool
with any arbitrary implementation of regular expressions; they need to
speak the same language.

https://www.gnu.org/software/emacs/manual/html_node/emacs/Regexps.html

https://emacs.stackexchange.com/q/55601 might help too.

> trying to regex replace the comments with

    \/\*(.|\n)*?\*\/

I'm guessing you want this:

    "/\\*\\(.\\|\n\\)*?\\*/"

Interactively that would be:

    /\*\(.\|
    \)*?\*/

----------------------------------------------------------------------
7890yuiop · 2022-02-09 09:06

> `M-x reb-change-syntax <RET> string <RET>`

`C-c TAB`

> `re-builder` is also able to handle ... `rx` style regexps, if you
install some packages.

Also if you don't.

----------------------------------------------------------------------
ShadowRylander · 2022-02-09 10:08

Thanks for pointing me in the direction of `re-builder`; I'll be sure
to check it out!

----------------------------------------------------------------------
ShadowRylander · 2022-02-09 10:13

I was using [regexer](https://regexr.com/), but yep; that did the
trick! I'll be sure to use `re-builder` in the future, then, and
thanks for the links as well!

----------------------------------------------------------------------
w08r · 2022-02-09 20:24

I really like visual-regexp [1] and the steroids add on [2] for an
alternative way to visually try regex replacements and for choosing
different regex interpreters respectively.

[1] https://github.com/benma/visual-regexp.el
[2] https://github.com/benma/visual-regexp-steroids.el/

----------------------------------------------------------------------
ShadowRylander · 2022-02-09 20:28

Thanks for the packages; I'll be sure to use them the next time I work
with regexps, especially the second one!

----------------------------------------------------------------------
SlowValue · 2022-02-11 20:30

>>     M-x reb-change-syntax <RET> string <RET>
>
> C-c TAB

Your shortcut isn't complete, right? Also sometimes I prefer to give
function names.