class XMLSerializer

class XMLSerializer {
    
    /** @var \XMLWriter */
    private $writer;
    
    /** @var Token */
    private $previousToken;
    
    /** @var NamespaceUri */
    private $xmlns;
    
    /**
     * XMLSerializer constructor.
     *
     * @param NamespaceUri $xmlns
     */
    public function __construct(?NamespaceUri $xmlns = null) {
        if ($xmlns === null) {
            $xmlns = new NamespaceUri('https://github.com/theseer/tokenizer');
        }
        $this->xmlns = $xmlns;
    }
    public function toDom(TokenCollection $tokens) : DOMDocument {
        $dom = new DOMDocument();
        $dom->preserveWhiteSpace = false;
        $dom->loadXML($this->toXML($tokens));
        return $dom;
    }
    public function toXML(TokenCollection $tokens) : string {
        $this->writer = new \XMLWriter();
        $this->writer
            ->openMemory();
        $this->writer
            ->setIndent(true);
        $this->writer
            ->startDocument();
        $this->writer
            ->startElement('source');
        $this->writer
            ->writeAttribute('xmlns', $this->xmlns
            ->asString());
        if (\count($tokens) > 0) {
            $this->writer
                ->startElement('line');
            $this->writer
                ->writeAttribute('no', '1');
            $this->previousToken = $tokens[0];
            foreach ($tokens as $token) {
                $this->addToken($token);
            }
        }
        $this->writer
            ->endElement();
        $this->writer
            ->endElement();
        $this->writer
            ->endDocument();
        return $this->writer
            ->outputMemory();
    }
    private function addToken(Token $token) : void {
        if ($this->previousToken
            ->getLine() < $token->getLine()) {
            $this->writer
                ->endElement();
            $this->writer
                ->startElement('line');
            $this->writer
                ->writeAttribute('no', (string) $token->getLine());
            $this->previousToken = $token;
        }
        if ($token->getValue() !== '') {
            $this->writer
                ->startElement('token');
            $this->writer
                ->writeAttribute('name', $token->getName());
            $this->writer
                ->writeRaw(\htmlspecialchars($token->getValue(), \ENT_NOQUOTES | \ENT_DISALLOWED | \ENT_XML1));
            $this->writer
                ->endElement();
        }
    }

}