protected function isStringLiteral(&$length, &$content)
    {
        if ($this->substring(1) !== "'") {
            return false;
        }

        $offset = $this->offset;
        while (true) {
            $offset = $this->indexAfter("'", $offset + 1);
            if ($this->substring(1, true, $offset) !== "'") {
                break;
            }
        }
        $length = $offset - $this->offset;
        $content = strtr($this->substring($length - 2, true, $this->offset + 1), ["''" => "'"]);
        return true;
    }
protected function isStringLiteral(&$length, &$content)
    {
        if ($this->substring(1) !== "'") {
            return false;
        }

        $offset = $this->offset;
        while (true) {
            $offset = $this->indexAfter("'", $offset + 1);
            if ($this->substring(1, true, $offset) !== "'") {
                break;
            }
        }
        $length = $offset - $this->offset;
        $content = strtr($this->substring($length - 2, true, $this->offset + 1), ["''" => "'"]);
        return true;
    }
{@inheritdoc}