WP_HTML_Processor::step_in_frameset(): bool

4518	private function step_in_frameset(): bool {4519		$tag_name   = $this->get_token_name();4520		$token_type = $this->get_token_type();4521		$op_sigil   = '#tag' === $token_type ? ( $this->is_tag_closer() ? '-' : '+' ) : '';4522		$op         = "{$op_sigil}{$tag_name}";4523 4524		switch ( $op ) {4525			/*4526			 * > A character token that is one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF),4527			 * >   U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE4528			 * >4529			 * > Insert the character.4530			 *4531			 * This algorithm effectively strips non-whitespace characters from text and inserts4532			 * them under HTML. This is not supported at this time.4533			 */4534			case '#text':4535				if ( parent::TEXT_IS_WHITESPACE === $this->text_node_classification ) {4536					return $this->step_in_body();4537				}4538				$this->bail( 'Non-whitespace characters cannot be handled in frameset.' );4539				break;4540 4541			/*4542			 * > A comment token4543			 */4544			case '#comment':4545			case '#funky-comment':4546			case '#presumptuous-tag':4547				$this->insert_html_element( $this->state->current_token );4548				return true;4549 4550			/*4551			 * > A DOCTYPE token4552			 */4553			case 'html':4554				// Parse error: ignore the token.4555				return $this->step();4556 4557			/*4558			 * > A start tag whose tag name is "html"4559			 */4560			case '+HTML':4561				return $this->step_in_body();4562 4563			/*4564			 * > A start tag whose tag name is "frameset"4565			 */4566			case '+FRAMESET':4567				$this->insert_html_element( $this->state->current_token );4568				return true;4569 4570			/*4571			 * > An end tag whose tag name is "frameset"4572			 */4573			case '-FRAMESET':4574				/*4575				 * > If the current node is the root html element, then this is a parse error;4576				 * > ignore the token. (fragment case)4577				 */4578				if ( $this->state->stack_of_open_elements->current_node_is( 'HTML' ) ) {4579					return $this->step();4580				}4581 4582				/*4583				 * > Otherwise, pop the current node from the stack of open elements.4584				 */4585				$this->state->stack_of_open_elements->pop();4586 4587				/*4588				 * > If the parser was not created as part of the HTML fragment parsing algorithm4589				 * > (fragment case), and the current node is no longer a frameset element, then4590				 * > switch the insertion mode to "after frameset".4591				 */4592				if ( ! isset( $this->context_node ) && ! $this->state->stack_of_open_elements->current_node_is( 'FRAMESET' ) ) {4593					$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_AFTER_FRAMESET;4594				}4595 4596				return true;4597