protected function getMatch($expr)
	{
		if (preg_match($this->regexp, $expr, $m))
		{
			foreach ($m as $name => $match)
			{
				if ($match !== '' && isset($this->callbacks[$name]))
				{
					return [$name, $this->getArguments($m, $name)];
				}
			}
		}

		return null;
	}