Clamp isize values returned by signed_difference

[Dr-Emann]

Since the difference of two usizes may not fit in an isize, clamp the
values to isize::MIN/MAX when the difference cannot be represented.

Also, be careful to avoid subtracting with overflow when computing the
diff

I couldn't think of a more succinct way to perform a clamping difference,
I'd be happy if there's a way to do it cleaner.

[codecov]

Codecov Report

Merging #11 (a6e84ee) into main (e1cc2ee) will increase coverage by 0.9%.
The diff coverage is 100.0%.

Impacted Files	Coverage Δ
src/lib.rs	96.1% <100.0%> (+1.1%)	⬆️

[jonhoo]

I think you can do:

if a > b {
  isize::try_from(a - b).unwrap_or(isize::MAX)
} else {
  isize::try_from(b - a).map(isize::saturaing_neg).unwrap_or(isize::MIN)
}

It would be a lot nicer with rust-lang/rust#87840, but for now I think you need ^.

[Dr-Emann]

Ah, yeah. I think even map(|i| -i) would work, the value will always be positive, so there's no need for saturating_neg, which only acts differently for isize::MIN

[jonhoo]

Thanks!

[jonhoo]

Released as 0.1.9 🎉