Iteration without an iterator

Hi,
I'm interested in whether hashbrown can be used for implementing Lua tables for Luster. (Note: I'm not the owner, just someone interested in the project!)

The unusual requirements for Lua's tables are:

1. Lua's next(table, item) function returns the "next" item in the table, given another.
2. Iteration using next has to be stable when removing items during the iteration.

I've had a look and think that hashbrown can support this with not much modification, and prototyped it here (a few months ago, so I haven't yet caught up on recent changes; this was before it was moved to rust-lang):

https://github.com/jugglerchris/hashbrown/tree/hash_next

I added a fn next_after(&self, key: Option<&K>) -> Option<(&K, &V)> which simply steps through hash buckets via a RawIterRange constructed to point part way through to implement #1, and #2 happens for free by using tombstones when removing (which relies on there not being a resize when shrinking too far; I'm not confident I haven't missed any cases).

I would be interested to know if functionality like this would be considered for hashbrown itself (I could understand not; I can certainly see not wanting to guarantee no resize on removal), or if not whether I've missed any obvious issues if I (or someone else) were to maintain a fork with these changes.

Thanks! I've certainly enjoyed looking through and having a play either way. :-)

Review the linked hash_next prototype, especially next_after and its use of RawIterRange, then compare its behavior with current hashbrown removal and resizing semantics. Check whether Lua's next requirements remain stable after removals and whether hashbrown should guarantee them; done means reaching a clear decision about support or fork viability.