Registry::filter

public function filter(callable $predicate): self
{
	$newCollection = clone $this;
	$keyToUnset = [];

	foreach ($newCollection as $key => $item)
	{
		if (!$predicate($item))
		{
			$keyToUnset[] = $key;
		}
	}

	foreach ($keyToUnset as $key)
	{
		unset($newCollection[$key]);
	}

	return $newCollection;
}