private function getControlStructureTokens()
    {
        static $tokens = null;

        if (null === $tokens) {
            $tokens = [
                T_IF,
                T_ELSEIF,
                T_FOR,
                T_FOREACH,
                T_WHILE,
                T_DO,
                T_CATCH,
                T_SWITCH,
                T_DECLARE,
            ];
        }

        return $tokens;
    }