public static function getCaptureNames($regexp)
	{
		$map        = [''];
		$regexpInfo = self::parse($regexp);
		foreach ($regexpInfo['tokens'] as $tok)
		{
			if ($tok['type'] === 'capturingSubpatternStart')
			{
				$map[] = (isset($tok['name'])) ? $tok['name'] : '';
			}
		}

		return $map;
	}