private class ArrayMapKeys[K, E]
	super RemovableCollection[K]
	# The original map
	var map: ArrayMap[K, E]
	redef fun count(k) do if self.has(k) then return 1 else return 0
	redef fun first do return self.map._items.first.first
	redef fun has(k) do return self.map.index(k) >= 0
	redef fun has_only(k) do return (self.has(k) and self.length == 1) or self.is_empty
	redef fun is_empty do return self.map.is_empty
	redef fun length do return self.map.length
	redef fun iterator do return new MapKeysIterator[K, E](self.map.iterator)
	redef fun clear do self.map.clear
	redef fun remove(key)
	do
		var i = self.map.index(key)
		if i >= 0 then self.map.remove_at_index(i)
	end
	redef fun remove_all(key) do self.remove(key)
end