HTML-DOM/lib/DOM/Element.php

<?php
declare(strict_types=1);
namespace dW\HTML5;

class Element extends \DOMElement {
    use Ancestor, Descendant {
        Ancestor::compare insteadof Descendant;
    }

    // Used for template elements
    public $content = null;

    public function __construct(string $name, string $value = '', string $namespaceURI = '') {
        parent::__construct($name, $value, $namespaceURI);

        if ($name === 'template' && $namespaceURI === '') {
            $this->content = $this->ownerDocument->createDocumentFragment();
        }
    }

    public function isMathMLTextIntegrationPoint(): bool {
        return (
            $this->namespaceURI === Parser::MATHML_NAMESPACE && (
                $this->nodeName === 'mi' || $this->nodeName === 'mo' || $this->nodeName === 'mn' || $this->nodeName === 'ms' || $this->nodeName === 'mtext'
            )
        );
    }

    public function isHTMLIntegrationPoint(): bool {
        $encoding = strtolower($this->getAttribute('encoding'));

        return ((
                $this->namespaceURI === Parser::MATHML_NAMESPACE &&
                $this->nodeName === 'annotation-xml' && (
                    $encoding === 'text/html' || $encoding === 'application/xhtml+xml'
                )
            ) || (
                $this->namespaceURI === Parser::SVG_NAMESPACE && (
                    $this->nodeName === 'foreignObject' || $this->nodeName === 'desc' || $this->nodeName === 'title'
                )
            )
        );
    }
}