interface EditorXssFilterInterface

interface EditorXssFilterInterface {
    
    /**
     * Filters HTML to prevent XSS attacks when a user edits it in a text editor.
     *
     * Should filter as minimally as possible, only to remove XSS attack vectors.
     *
     * Is only called when:
     * - loading a non-XSS-safe text editor for a $format that contains a filter
     *   preventing XSS attacks (a FilterInterface::TYPE_HTML_RESTRICTOR filter):
     *   if the output is safe, it should also be safe to edit.
     * - loading a non-XSS-safe text editor for a $format that doesn't contain a
     *   filter preventing XSS attacks, but we're switching from a previous text
     *   format ($original_format is not NULL) that did prevent XSS attacks: if
     *   the output was previously safe, it should be safe to switch to another
     *   text format and edit.
     *
     * @param string $html
     *   The HTML to be filtered.
     * @param \Drupal\filter\FilterFormatInterface $format
     *   The text format configuration entity. Provides context based upon which
     *   one may want to adjust the filtering.
     * @param \Drupal\filter\FilterFormatInterface|null $original_format
     *   (optional) The original text format configuration entity (when switching
     *   text formats/editors). Also provides context based upon which one may
     *   want to adjust the filtering.
     *
     * @return string
     *   The filtered HTML that cannot cause any XSSes anymore.
     */
    public static function filterXss($html, FilterFormatInterface $format, FilterFormatInterface $original_format = NULL);

}