Extended DOMElement for generate HTML tags

Tag.php

<?php

/**
 * HTML tag.
 */
class Tag extends DOMElement implements TagInterface
{
    public function __construct(string $name, string $value = '')
    {
        parent::__construct($name, $value);
    }

    /**
     * @param iterable $attributes the attributes, attribute name/value pairs.
     */
    public function setAttributes(iterable $attributes): self
    {
        if ($this->hasAttributes()) {
            $this->resetAttributes();
        }
        foreach ($attributes as $name => $value) {
            $this->setAttribute($name, $value);
        }

        return $this;
    }

    /**
     * 
     */
    public function setAttribute($name, $value): DOMAttr
    {
        // @todo support passing arrays in $value to set `data-*` and `aria-*` attributes
        return parent::setAttribute($name, $this->normalizeAttribute($name, $value));
    }

    /**
     * Returns encoded value.
     *
     * @param mixed $value the value to encode
     */
    protected function encodeValue($value): string
    {
        return (string) json_encode(
            $value,
            JSON_FORCE_OBJECT
            | JSON_NUMERIC_CHECK
            | JSON_PARTIAL_OUTPUT_ON_ERROR
            | JSON_PRESERVE_ZERO_FRACTION
            | JSON_UNESCAPED_SLASHES
            | JSON_UNESCAPED_UNICODE
            | JSON_THROW_ON_ERROR
        );
    }
    
    /**
     * Returns normalized value of attribute.
     *
     * @param string $name the attribute name
     * @param mixed $value the attribute value
     */
    protected function normalizeAttribute(string $name, $value): string
    {
        if (is_object($value)) {
            if (method_exists($value, '__toString')) {
                $value = (string) $value;
            } else {
                $value = (array) $value;
            }
        }
        if (is_array($value)) {
            if (empty($value)) {
                $value = '';
            } elseif ($name === 'style') {
                if (!isset($value[0])) {
                    foreach ($value as $key => $val) {
                        $value[$key] = $key . ': ' . str_replace('"', "'", $this->encodeValue($val));
                    }
                }
                $value = implode('; ', $value);
            } else {
                $value = implode(' ', array_filter($value));
            }
        }

        return is_string($value) ? $value : $this->encodeValue($value);
    }

    /**
     * Removes all attributes of tag.
     */
    public function resetAttributes(): self
    {
        foreach ($this->attributes as $attribute) {
            $this->removeAttributeNode($attribute);
        }

        return $this;
    }

    /**
     * Sets inner content(text or HTML) of tag.
     */
    public function setContent(...$values): self
    {
        $this->removeContent();
        
        foreach ($values as $value) {
            if (is_callable($value)) {
                $value = call_user_func($value, $this, $this->ownerDocument);
            }
            if ($value instanceof DOMElement) {
                $this->appendChild($value);
            } elseif ($value instanceof SimpleXMLElement) {
                $this->appendChild(dom_import_simplexml($value));
            } else {
                $value = (string) $value;
                // Dirty, but fast solution to detect HTML tags
                if (strpos($value, '<') !== false && strpos($value, '>') !== false) {
                    // HTML:
                    $fragment = $this->ownerDocument->createDocumentFragment();
                    $fragment->appendXML($value);
                    $this->appendChild($fragment);
                } else {
                    // Text:
                    $this->appendChild($this->ownerDocument->createTextNode($value));
                }
            }
        }

        return $this;
    }

    public function removeContent(): self
    {
        foreach ($this->childNodes as $child) {
            $this->removeChild($child);
        }

        return $this;
    }

    public function __toString(): string
    {
        return (string) $this->ownerDocument->saveHTML($this);
    }
}

TagFactory.php

<?php

/**
 * HTML tag factory.
 */
class TagFactory
{
    /**
     * @var DOMDocument the HTML document
     */
    protected $document;

    /**
     * @param bool $html5 if `TRUE`, then generate HTML 5 document, else, HTML 4 document
     */
    public function __construct(bool $html5 = true)
    {
        $dom = new DOMImplementation();
        if ($html5) {
            $docType = $dom->createDocumentType('html');
        } else {
            $docType = $dom->createDocumentType(
                'HTML',
                '-//W3C//DTD HTML 4.01 Transitional//EN',
                'http://www.w3.org/TR/html4/loose.dtd'
            );
        }
        $this->document = $dom->createDocument('', 'html', $docType);
        $this->document->registerNodeClass(DOMElement::class, Tag::class);
        // @todo
        // $this->document->registerNodeClass(DOMAttr::class, TagAttribute::class);
    }

    /**
     * Creates new `TagInterface` instance.
     *
     * @param string $name the tag name
     * @param iterable $attributes the tag attributes
     * @param string|DOMElement|SimpleXMLElement|TagInterface|callable|null $content the inner text/HTML, callback syntax:
     * `function (TagInterface $tag, DOMDocument $document): TagInterface|string`
     * @return TagInterface
     */
    public function createTag(string $name, iterable $attributes = [], $content = null): TagInterface
    {
        // @todo remove tag from document instead cloning
        $document = $this->document->cloneNode();
        $tag = $document->documentElement->appendChild($document->createElement($name));
        $tag->setAttributes($attributes);
        if ($content !== null) {
            $tag->setContent($content);
        }

        return $tag;
    }
}

TagInterface.php

<?php

/**
 * Interface of HTML tags.
 */
interface TagInterface
{
    public function setAttributes(iterable $attributes);
    /**
     * @sstring|DOMElement|SimpleXMLElement|TagInterface|callable|null
     */
    public function setContent($content);
    public function __toString(): string;
    
}