FilterHtmlEscape.php

<?php

namespace Drupal\filter\Plugin\Filter;

use Drupal\filter\FilterProcessResult;
use Drupal\filter\Plugin\FilterBase;

/**
 * Provides a filter to display any HTML as plain text.
 *
 * @Filter(
 *   id = "filter_html_escape",
 *   title = @Translation("Display any HTML as plain text"),
 *   type = Drupal\filter\Plugin\FilterInterface::TYPE_HTML_RESTRICTOR,
 *   weight = -10
 * )
 */
class FilterHtmlEscape extends FilterBase {
    
    /**
     * {@inheritdoc}
     */
    public function process($text, $langcode) {
        return new FilterProcessResult(_filter_html_escape($text));
    }
    
    /**
     * {@inheritdoc}
     */
    public function getHTMLRestrictions() {
        // Nothing is allowed.
        return [
            'allowed' => [],
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function tips($long = FALSE) {
        return $this->t('No HTML tags allowed.');
    }

}