lexInterpolation example

break;

                case self::STATE_VAR:
                    $this->lexVar();
                    break;

                case self::STATE_STRING:
                    $this->lexString();
                    break;

                case self::STATE_INTERPOLATION:
                    $this->lexInterpolation();
                    break;
            }
        }

        $this->pushToken(/* Token::EOF_TYPE */ -1);

        if (!empty($this->brackets)) {
            list($expect, $lineno) = array_pop($this->brackets);
            throw new SyntaxError(sprintf('Unclosed "%s".', $expect), $lineno, $this->source);
        }