str: add cut and cutn methods

[hotandcoldfever]

These methods just wrap replace/replacen and provide a more concise way to remove patterns from strs

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[jfager]

This isn’t what I’d expect a string op named cut to do.

[hotandcoldfever]

I don't think there's any general expectation for rust methods to have the same behaviour as similarly named unix commands, and I think the name cut does make sense for this since it effectively cuts content out of the string according to the provided pattern. But I'm down w/ considering other names. I originally was gonna use remove but decided against it when I remembered String's remove method

[leoyvens]

Is there any previous discussion on this? Seems too trivial to be in std.

[jfager]

There's no general expectation for rust methods to match unix commands, but they usually either have some precedent or near-match in other ecosystems, or, conversely, conform to Rust's naming conventions for the sorts of operations that are unique to the language.

Afaik 'cut' doesn't show up in many (any?) other languages' standard libraries, while the unix command is used widely in a similar enough context that I think it's reasonable to hold up as the prevailing prior art for the name in this particular case.

[clarfonthey]

IMO replace returning String instead of Cow<str> is a mistake, and I'd prefer that this method do that.

Also, acut_in_place would be nice, using &mut str.

[bors]

☔ The latest upstream changes (presumably #47813) made this pull request unmergeable. Please resolve the merge conflicts.

[hotandcoldfever]

@jfager Point taken. Maybe a name like purge, delete, snip, blank?
@clarcharr So somethin like

fn cut<'a, P: Pattern<'a>>(&'a self, pattern: P) -> Cow<'a, str> {
    let result = self.replace(pattern, "");

    match result == self {
        false => result.into(),
        true => self.into()
    }
}

? cut_in_place could be useful I guess and I could take a crack at it if cut and cutn get merged
@leodasvacas Yea this is pretty trivial but it'd just be nice to have a more concise way to remove things from strings, and I don't think it's any more trivial than having flatten when you can use flat_map(|x| x) or vec![a, b] when you can use let mut vec = Vec::new(); vec.push(a); vec.push(b); etc. As far as I'm aware there's no previous discussions about this

[clarfonthey]

@cool-cool-sweat yes, but please don't actually write that code; it's less efficient because it still allocates unconditionally.

As far as naming goes, I like remove_all and remove_n

[pietroalbini]

Thank you for this PR @cool-cool-sweat! The triage team will periodically check in to make sure the PR is properly reviewed.

Ping from triage @bluss! This PR needs your review.

[hotandcoldfever]

Gonna close this since there ain't much interest