Implement in place sorting of OrderMap and OrderSet

[vitiral]

Feature request: Add in-place sorting methods to OrderMap (and OrderSet). Similar to the existing .sorted_by, these methods can allow the user to sort by either keys or values or both by supplying all of those to the closure.

For example:

fn sort_by<F>(&mut self, cmp: F)
    where F: FnMut(&K, &V, &K, &V) -> Ordering;

Original issue:

---

Feature request: add sort_keys<K:Ord+Hash>(&mut self) to do an inplace sort.

This library is INCREDIBLE when assertions need to be made because I can do an inplace sort and the diffs look good (when combined with pretty_assertions of course).

I did a naive implementation like this:

pub fn sort_ordermap<K:Ord+Hash, V>(m: &mut OrderMap<K, V>) {
    let mut ordered: Vec<_> = m.drain(..).collect();
    ordered.sort_by(|left, right| left.0.cmp(&right.0));
    m.extend(ordered.drain(..));
}

pub fn sort_orderset<K:Ord+Hash>(m: &mut OrderSet<K>) {
    let mut ordered: Vec<_> = m.drain(..).collect();
    ordered.sort_by(|left, right| left.cmp(&right));
    m.extend(ordered.drain(..));
}

I'm sure a better one can be done with full access to the underlying data structure.

[clarfonthey]

You could also use sort_by_key(|elem| elem.0) for the map and just sort for the orderset.

[vitiral]

@clarcharr do you mean it could be named that? I suggested sort for OrderSet in the title of the issue. I'm not sure what sort_by_key means -- you could implement sort_by in addition to sort_keys -- both could be useful!

[clarfonthey]

Sorry; to clarify, you could replace the code in the post with:

pub fn sort_ordermap<K:Ord+Hash, V>(m: &mut OrderMap<K, V>) {
    let mut ordered: Vec<_> = m.drain(..).collect();
    ordered.sort_by_key(|x| x.0);
    m.extend(ordered);
}

pub fn sort_orderset<K:Ord+Hash>(m: &mut OrderSet<K>) {
    let mut ordered: Vec<_> = m.drain(..).collect();
    ordered.sort();
    m.extend(ordered);
}

[vitiral]

Oh, I didn't realize that sort_by_key was a thing! Thanks!

[bluss]

I agree with this feature request. No comment on whether it is possible easily

[bluss]

A side note about sort_by_key, is that the key version sometimes will need to clone the keys when the _by version does not.

[bluss]

I have taken the liberty to edit the original post to better reflect what I think we are seeking. It's your post, so you are free to edit it too, it's a collaboration..

[vitiral]

sort_by would be a good first start. Additional methods (like sort_keys) can be added later at other's requests.

[bluss]

Implemented as an experiment in #57, (building upon the retain in place PR, so that one needs to merge first).

Yes, instead of Vec's .sort() ordermap should probably have .sort_keys(), that sounds nice