WP_HTML_Active_Formatting_Elements

37class WP_HTML_Active_Formatting_Elements {38	/**39	 * Holds the stack of active formatting element references.40	 *41	 * @since 6.4.042	 *43	 * @var WP_HTML_Token[]44	 */45	private $stack = array();46 47	/**48	 * Reports if a specific node is in the stack of active formatting elements.49	 *50	 * @since 6.4.051	 *52	 * @param WP_HTML_Token $token Look for this node in the stack.53	 * @return bool Whether the referenced node is in the stack of active formatting elements.54	 */55	public function contains_node( WP_HTML_Token $token ) {56		foreach ( $this->walk_up() as $item ) {57			if ( $token->bookmark_name === $item->bookmark_name ) {58				return true;59			}60		}61 62		return false;63	}64 65	/**66	 * Returns how many nodes are currently in the stack of active formatting elements.67	 *68	 * @since 6.4.069	 *70	 * @return int How many node are in the stack of active formatting elements.71	 */72	public function count() {73		return count( $this->stack );74	}75 76	/**77	 * Returns the node at the end of the stack of active formatting elements,78	 * if one exists. If the stack is empty, returns null.79	 *80	 * @since 6.4.081	 *82	 * @return WP_HTML_Token|null Last node in the stack of active formatting elements, if one exists, otherwise null.83	 */84	public function current_node() {85		$current_node = end( $this->stack );86 87		return $current_node ? $current_node : null;88	}89 90	/**91	 * Inserts a "marker" at the end of the list of active formatting elements.92	 *93	 * > The markers are inserted when entering applet, object, marquee,94	 * > template, td, th, and caption elements, and are used to prevent95	 * > formatting from "leaking" into applet, object, marquee, template,96	 * > td, th, and caption elements.97	 *98	 * @see https://html.spec.whatwg.org/#concept-parser-marker99	 *100	 * @since 6.7.0101	 */102	public function insert_marker(): void {103		$this->push( new WP_HTML_Token( null, 'marker', false ) );104	}105 106	/**107	 * Pushes a node onto the stack of active formatting elements.108	 *109	 * @since 6.4.0110	 *111	 * @see https://html.spec.whatwg.org/#push-onto-the-list-of-active-formatting-elements112	 *113	 * @param WP_HTML_Token $token Push this node onto the stack.114	 */115	public function push( WP_HTML_Token $token ) {116		/*