Is it necessary to store and check `keys`? For collisions?

[RoDmitry]

I want to try out mphf, but I don't understand how it handles collisions. Are collisions for never seen keys can happen? Maybe add this info to the mphf docs somewhere.

entropy-map/src/map_with_dict.rs

Lines 114 to 120 in 0943c6d

	if self.keys.get_unchecked(idx) == key {
	// SAFETY: `idx` and `value_idx` are always within bounds (ensure during construction)
	let value_idx = *self.values_index.get_unchecked(idx);
	Some(self.values_dict.get_unchecked(value_idx))
	} else {
	None
	}

What is this keys check for?

[austinhartzheim]

If the entire set of keys you will ever query also exist the MPHF, you will not encounter collisions. The MPHF will fail to be constructed if there is an unresolvable collision (e.g., due to poor choice of hash function).

If you query with keys that are unknown at the time of construction, this additional check prevents collisions.

[RoDmitry]

If you query with keys that are unknown at the time of construction, this additional check prevents collisions.

That's what I thought. Then it better be added to docs.