Fix the conversion of private names to public names

[nex3]

This handles cases where the private names start with multiple dashes or underscores or are even composed entirely of dashes and underscores. It also fixes bugs where names starting with underscores weren't considered private.

Closes #273

[Tofandel]

In this case maybe it's better to only run substring(1), otherwise multiple dashes will get replaced to 1 dash still

[nex3]

Why? _privateToPublic() should handle multiple dashes gracefully.

[Tofandel]

Suggested change

	return (isPrivate ? '-' : '') + withoutPrefix;
	return (isPrivate ? name.substring(0, 1) : '') + withoutPrefix;

[nex3]

Generally I'm okay with leaning towards encouraging -, since that's definitely the more CSS-style prefix.

[Tofandel]

Yes it's just for the sake of avoiding unecessary changes during a migration, but I definitely don't understand everything that's happening after this runs, because some tests that look like they should fail returning a dash, don't 🤷

<==> arguments
--migrate-deps --remove-prefix=app
<==> input/entrypoint.scss
@import "library";
a {
  color: $app-var;
}

<==> input/_library.scss
$_app-red: red;
$app-var: $_app-red;

<==> output/entrypoint.scss
@use "library";
a {
  color: library.$var;
}

<==> output/_library.scss
$_red: red;
$var: $_red;

Ok, that one fails

<==> arguments
--migrate-deps --remove-prefix=app
<==> input/entrypoint.scss
@import "library";
a {
  color: $app-var;
}

<==> input/_library.scss
$__app-red: red;
$app-var: $__app-red;

<==> output/entrypoint.scss
@use "library";
a {
  color: library.$var;
}

<==> output/_library.scss
$__red: red;
$var: $__red;

So now it's just a question of do we want to preserve the original number of dashes/underscore or not? (My previous implementation did)

[Tofandel]

I added suggested tests and fixed the reported behaviors of remove-prefix in #276

So you can merge that in this branch

[pamelalozano16]

Why are you iterating through the identifier? Shouldn't returning the substring without the initial - or _ should be enough?

[Tofandel]

There can be multiple dashes or underscore, removing only one if there is multiple would lead to the variable still being private, see linked issue.

It's just iterating each char until it finds a character that's not an underscore or dash, then returns the string without the iterated part

This is more performant than regex

[pamelalozano16]

What about identifier.replace(Regex(r"^-|^_"),"") ?

[Tofandel]

The correct one would be identifier.replace(Regex(r"^[-_]+"),"")

[Tofandel]

And if the returned string is empty then return a generated var

[nex3]

I habitually avoid regular expressions because they're somewhat more expensive than explicit parsing. If you'd prefer it, I can make the change, but I think the current way does work.

[Tofandel]

I thought because of this line, here we return '-' but we should return the original private prefix.

But from testing, it seems there is some magic running after that already and it keeps the original private prefix somehow

[pamelalozano16]

LGTM