WP_HTML_Processor::seek( string $bookmark_name ): bool

5468	public function seek( $bookmark_name ): bool {5469		// Flush any pending updates to the document before beginning.5470		$this->get_updated_html();5471 5472		$actual_bookmark_name = "_{$bookmark_name}";5473		$processor_started_at = $this->state->current_token5474			? $this->bookmarks[ $this->state->current_token->bookmark_name ]->start5475			: 0;5476		$bookmark_starts_at   = $this->bookmarks[ $actual_bookmark_name ]->start;5477		$direction            = $bookmark_starts_at > $processor_started_at ? 'forward' : 'backward';5478 5479		/*5480		 * If seeking backwards, it's possible that the sought-after bookmark exists within an element5481		 * which has been closed before the current cursor; in other words, it has already been removed5482		 * from the stack of open elements. This means that it's insufficient to simply pop off elements5483		 * from the stack of open elements which appear after the bookmarked location and then jump to5484		 * that location, as the elements which were open before won't be re-opened.5485		 *5486		 * In order to maintain consistency, the HTML Processor rewinds to the start of the document5487		 * and reparses everything until it finds the sought-after bookmark.5488		 *5489		 * There are potentially better ways to do this: cache the parser state for each bookmark and5490		 * restore it when seeking; store an immutable and idempotent register of where elements open5491		 * and close.5492		 *5493		 * If caching the parser state it will be essential to properly maintain the cached stack of5494		 * open elements and active formatting elements when modifying the document. This could be a5495		 * tedious and time-consuming process as well, and so for now will not be performed.5496		 *5497		 * It may be possible to track bookmarks for where elements open and close, and in doing so5498		 * be able to quickly recalculate breadcrumbs for any element in the document. It may even5499		 * be possible to remove the stack of open elements and compute it on the fly this way.5500		 * If doing this, the parser would need to track the opening and closing locations for all5501		 * tokens in the breadcrumb path for any and all bookmarks. By utilizing bookmarks themselves5502		 * this list could be automatically maintained while modifying the document. Finding the5503		 * breadcrumbs would then amount to traversing that list from the start until the token5504		 * being inspected. Once an element closes, if there are no bookmarks pointing to locations5505		 * within that element, then all of these locations may be forgotten to save on memory use5506		 * and computation time.5507		 */5508		if ( 'backward' === $direction ) {5509 5510			/*5511			 * When moving backward, stateful stacks should be cleared.5512			 */5513			foreach ( $this->state->stack_of_open_elements->walk_up() as $item ) {5514				$this->state->stack_of_open_elements->remove_node( $item );5515			}5516 5517			foreach ( $this->state->active_formatting_elements->walk_up() as $item ) {5518				$this->state->active_formatting_elements->remove_node( $item );5519			}5520 5521			/*5522			 * **After** clearing stacks, more processor state can be reset.5523			 * This must be done after clearing the stack because those stacks generate events that5524			 * would appear on a subsequent call to `next_token()`.5525			 */5526			$this->state->frameset_ok                       = true;5527			$this->state->stack_of_template_insertion_modes = array();5528			$this->state->head_element                      = null;5529			$this->state->form_element                      = null;5530			$this->state->current_token                     = null;5531			$this->current_element                          = null;5532			$this->element_queue                            = array();5533 5534			/*5535			 * The absence of a context node indicates a full parse.5536			 * The presence of a context node indicates a fragment parser.5537			 */5538			if ( null === $this->context_node ) {5539				$this->change_parsing_namespace( 'html' );5540				$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_INITIAL;5541				$this->breadcrumbs           = array();5542 5543				$this->bookmarks['initial'] = new WP_HTML_Span( 0, 0 );5544				parent::seek( 'initial' );5545				unset( $this->bookmarks['initial'] );5546			} else {5547