lement, meaning that
				 *       when SVG and MathML support is added, this needs to differentiate between an
				 *       HTML element of the given name, such as `<center>`, and a foreign element of
				 *       the same given name.
				 */
				if ( ! $this->state->stack_of_open_elements->current_node_is( $tag_name ) ) {
					// @todo Indicate a parse error once it's possible.
				}

				$this->state->stack_of_open_elements->pop_until( $tag_name );
				$this->state->active_formatting_elements->clear_up_to_last_marker();
				$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_ROW;
				return true;

			/*
			 * > A start tag whose tag name is one of: "caption", "col", "colgroup", "tbody", "td",
			 * > "tfoot", "th", "thead", "tr"
			 */
			case '+CAPTION':
			case '+COL':
			case '+COLGROUP':
			case '+TBODY':
			case '+TD':
			case '+TFOOT':
			case '+TH':
			case '+THEAD':
			case '+TR':
				/*
				 * > Assert: The stack of open elements has a td or th element in table scope.
				 *
				 * Nothing to do here, except to verify in tests that this never appears.
				 */

				$this->close_cell();
				return $this->step( self::REPROCESS_CURRENT_NODE );

			/*
			 * > An end tag whose tag name is one of: "body", "caption", "col", "colgroup", "html"
			 */
			case '-BODY':
			case '-CAPTION':
			case '-COL':
			case '-COLGROUP':
			case '-HTML':
				// Parse error: ignore the token.
				return $this->step();

			/*
			 * > An end tag whose tag name is one of: "table", "tbody", "tfoot", "thead", "tr"
			 */
			case '-TABLE':
			case '-TBODY':
			case '-TFOOT':
			case '-THEAD':
			case '-TR':
				if ( ! $this->state->stack_of_open_elements->has_element_in_table_scope( $tag_name ) ) {
					// Parse error: ignore the token.
					return $this->step();
				}
				$this->close_cell();
				return $this->step( self::REPROCESS_CURRENT_NODE );
		}

		/*
		 * > Anything else
		 * >   Process the token using the rules for the "in body" insertion mode.
		 */
		return $this->step_in_body();
	}

	/**
	 * Parses next element in the 'in select' insertion mode.
	 *
	 * This internal function performs the 'in select' insertion mode
	 * logic for the generalized WP_HTML_Processor::step() function.
	 *
	 * @since 6.7.0
	 *
	 * @throws WP_HTML_Unsupported_Exception When encountering unsupported HTML input.
	 *
	 * @see https://html.spec.whatwg.org/multipage/parsing.html#parsing-main-inselect
	 * @see WP_HTML_Processor::step
	 *
	 * @return bool Whether an element was found.
	 */
	private function step_in_select(): bool {
		$token_name = $this->get_token_name();
		$token_type = $this->get_token_type();
		$op_sigil   = '#tag' === $token_type ? ( parent::is_tag_closer() ? '-' : '+' ) : '';
		$op         = "{$op_sigil}{$token_name}";

		switch ( $op ) {
			/*
			 * > Any other character token
			 */
			case '#text':
				/*
				 * > A character token that is U+0000 NULL
				 *
				 * If a text node only comprises null bytes then it should be
				 * entirely ignored and should not return to calling code.
				 */
				if ( parent::TEXT_IS_NULL_SEQUENCE === $this->text_node_classification ) {
					// Parse error: ignore the token.
					return $this->step();
				}

				$this->insert_html_element( $this->state->current_token );
				return true;

			/*
			 * > A comment token
			 */
			case '#comment':
			case '#funky-comment':
			case '#presumptuous-tag':
				$this->insert_html_element( $this->state->current_token );
				return true;

			/*
			 * > A DOCTYPE token
			 */
			case 'html':
				// Parse error: ignore the token.
				return $this->step();

			/*
			 * > A start tag whose tag name is "html"
			 */
			case '+HTML':
				return $this->step_in_body();

			/*
			 * > A start tag whose tag name is "option"
			 */
			case '+OPTION':
				if ( $this->state->stack_of_open_elements->current_node_is( 'OPTION' ) ) {
					$this->state->stack_of_open_elements->pop();
				}
				$this->insert_html_element( $this->state->current_token );
				return true;

			/*
			 * > A start tag whose tag name is "optgroup"
			 * > A start tag whose tag name is "hr"
			 *
			 * These rules are identical except for the treatment of the self-closing flag and
			 * the subsequent pop of the HR void element, all of which is handled elsewhere in the processor.
			 */
			case '+OPTGROUP':
			case '+HR':
				if ( $this->state->stack_of_open_elements->current_node_is( 'OPTION' ) ) {
					$this->state->stack_of_open_elements->pop();
				}

				if ( $this->state->stack_of_open_elements->current_node_is( 'OPTGROUP' ) ) {
					$this->state->stack_of_open_elements->pop();
				}

				$this->insert_html_element( $this->state->current_token );
				return true;

			/*
			 * > An end tag whose tag name is "optgroup"
			 */
			case '-OPTGROUP':
				$current_node = $this->state->stack_of_open_elements->current_node();
				if ( $current_node && 'OPTION' === $current_node->node_name ) {
					foreach ( $this->state->stack_of_open_elements->walk_up( $current_node ) as $parent ) {
						break;
					}
					if ( $parent && 'OPTGROUP' === $parent->node_name ) {
						$this->state->stack_of_open_elements->pop();
					}
				}

				if ( $this->state->stack_of_open_elements->current_node_is( 'OPTGROUP' ) ) {
					$this->state->stack_of_open_elements->pop();
					return true;
				}

				// Parse error: ignore the token.
				return $this->step();

			/*
			 * > An end tag whose tag name is "option"
			 */
			case '-OPTION':
				if ( $this->state->stack_of_open_elements->current_node_is( 'OPTION' ) ) {
					$this->state->stack_of_open_elements->pop();
					return true;
				}

				// Parse error: ignore the token.
				return $this->step();

			/*
			 * > An end tag whose tag name is "select"
			 * > A start tag whose tag name is "select"
			 *
			 * > It just gets treated like an end tag.
			 */
			case '-SELECT':
			case '+SELECT':
				if ( ! $this->state->stack_of_open_elements->has_element_in_select_scope( 'SELECT' ) ) {
					// Parse error: ignore the token.
					return $this->step();
				}
				$this->state->stack_of_open_elements->pop_until( 'SELECT' );
				$this->reset_insertion_mode_appropriately();
				return true;

			/*
			 * > A start tag whose tag name is one of: "input", "keygen", "textarea"
			 *
			 * All three of these tags are considered a parse error when found in this insertion mode.
			 */
			case '+INPUT':
			case '+KEYGEN':
			case '+TEXTAREA':
				if ( ! $this->state->stack_of_open_elements->has_element_in_select_scope( 'SELECT' ) ) {
					// Ignore the token.
					return $this->step();
				}
				$this->state->stack_of_open_elements->pop_until( 'SELECT' );
				$this->reset_insertion_mode_appropriately();
				return $this->step( self::REPROCESS_CURRENT_NODE );

			/*
			 * > A start tag whose tag name is one of: "script", "template"
			 * > An end tag whose tag name is "template"
			 */
			case '+SCRIPT':
			case '+TEMPLATE':
			case '-TEMPLATE':
				return $this->step_in_head();
		}

		/*
		 * > Anything else
		 * >   Parse error: ignore the token.
		 */
		return $this->step();
	}

	/**
	 * Parses next element in the 'in select in table' insertion mode.
	 *
	 * This internal function performs the 'in select in table' insertion mode
	 * logic for the generalized WP_HTML_Processor::step() function.
	 *
	 * @since 6.7.0
	 *
	 * @throws WP_HTML_Unsupported_Exception When encountering unsupported HTML input.
	 *
	 * @see https://html.spec.whatwg.org/#parsing-main-inselectintable
	 * @see WP_HTML_Processor::step
	 *
	 * @return bool Whether an element was found.
	 */
	private function step_in_select_in_table(): bool {
		$token_name = $this->get_token_name();
		$token_type = $this->get_token_type();
		$op_sigil   = '#tag' === $token_type ? ( parent::is_tag_closer() ? '-' : '+' ) : '';
		$op         = "{$op_sigil}{$token_name}";

		switch ( $op ) {
			/*
			 * > A start tag whose tag name is one of: "caption", "table", "tbody", "tfoot", "thead", "tr", "td", "th"
			 */
			case '+CAPTION':
			case '+TABLE':
			case '+TBODY':
			case '+TFOOT':
			case '+THEAD':
			case '+TR':
			case '+TD':
			case '+TH':
				// @todo Indicate a parse error once it's possible.
				$this->state->stack_of_open_elements->pop_until( 'SELECT' );
				$this->reset_insertion_mode_appropriately();
				return $this->step( self::REPROCESS_CURRENT_NODE );

			/*
			 * > An end tag whose tag name is one of: "caption", "table", "tbody", "tfoot", "thead", "tr", "td", "th"
			 */
			case '-CAPTION':
			case '-TABLE':
			case '-TBODY':
			case '-TFOOT':
			case '-THEAD':
			case '-TR':
			case '-TD':
			case '-TH':
				// @todo Indicate a parse error once it's possible.
				if ( ! $this->state->stack_of_open_elements->has_element_in_table_scope( $token_name ) ) {
					return $this->step();
				}
				$this->state->stack_of_open_elements->pop_until( 'SELECT' );
				$this->reset_insertion_mode_appropriately();
				return $this->step( self::REPROCESS_CURRENT_NODE );
		}

		/*
		 * > Anything else
		 */
		return $this->step_in_select();
	}

	/**
	 * Parses next element in the 'in template' insertion mode.
	 *
	 * This internal function performs the 'in template' insertion mode
	 * logic for the generalized WP_HTML_Processor::step() function.
	 *
	 * @since 6.7.0 Stub implementation.
	 *
	 * @throws WP_HTML_Unsupported_Exception When encountering unsupported HTML input.
	 *
	 * @see https://html.spec.whatwg.org/#parsing-main-intemplate
	 * @see WP_HTML_Processor::step
	 *
	 * @return bool Whether an element was found.
	 */
	private function step_in_template(): bool {
		$token_name = $this->get_token_name();
		$token_type = $this->get_token_type();
		$is_closer  = $this->is_tag_closer();
		$op_sigil   = '#tag' === $token_type ? ( $is_closer ? '-' : '+' ) : '';
		$op         = "{$op_sigil}{$token_name}";

		switch ( $op ) {
			/*
			 * > A character token
			 * > A comment token
			 * > A DOCTYPE token
			 */
			case '#text':
			case '#comment':
			case '#funky-comment':
			case '#presumptuous-tag':
			case 'html':
				return $this->step_in_body();

			/*
			 * > A start tag whose tag name is one of: "base", "basefont", "bgsound", "link",
			 * > "meta", "noframes", "script", "style", "template", "title"
			 * > An end tag whose tag name is "template"
			 */
			case '+BASE':
			case '+BASEFONT':
			case '+BGSOUND':
			case '+LINK':
			case '+META':
			case '+NOFRAMES':
			case '+SCRIPT':
			case '+STYLE':
			case '+TEMPLATE':
			case '+TITLE':
			case '-TEMPLATE':
				return $this->step_in_head();

			/*
			 * > A start tag whose tag name is one of: "caption", "colgroup", "tbody", "tfoot", "thead"
			 */
			case '+CAPTION':
			case '+COLGROUP':
			case '+TBODY':
			case '+TFOOT':
			case '+THEAD':
				array_pop( $this->state->stack_of_template_insertion_modes );
				$this->state->stack_of_template_insertion_modes[] = WP_HTML_Processor_State::INSERTION_MODE_IN_TABLE;
				$this->state->insertion_mode                      = WP_HTML_Processor_State::INSERTION_MODE_IN_TABLE;
				return $this->step( self::REPROCESS_CURRENT_NODE );

			/*
			 * > A start tag whose tag name is "col"
			 */
			case '+COL':
				array_pop( $this->state->stack_of_template_insertion_modes );
				$this->state->stack_of_template_insertion_modes[] = WP_HTML_Processor_State::INSERTION_MODE_IN_COLUMN_GROUP;
				$this->state->insertion_mode                      = WP_HTML_Processor_State::INSERTION_MODE_IN_COLUMN_GROUP;
				return $this->step( self::REPROCESS_CURRENT_NODE );

			/*
			 * > A start tag whose tag name is "tr"
			 */
			case '+TR':
				array_pop( $this->state->stack_of_template_insertion_modes );
				$this->state->stack_of_template_insertion_modes[] = WP_HTML_Processor_State::INSERTION_MODE_IN_TABLE_BODY;
				$this->state->insertion_mode                      = WP_HTML_Processor_State::INSERTION_MODE_IN_TABLE_BODY;
				return $this->step( self::REPROCESS_CURRENT_NODE );

			/*
			 * > A start tag whose tag name is one of: "td", "th"
			 */
			case '+TD':
			case '+TH':
				array_pop( $this->state->stack_of_template_insertion_modes );
				$this->state->stack_of_template_insertion_modes[] = WP_HTML_Processor_State::INSERTION_MODE_IN_ROW;
				$this->state->insertion_mode                      = WP_HTML_Processor_State::INSERTION_MODE_IN_ROW;
				return $this->step( self::REPROCESS_CURRENT_NODE );
		}

		/*
		 * > Any other start tag
		 */
		if ( ! $is_closer ) {
			array_pop( $this->state->stack_of_template_insertion_modes );
			$this->state->stack_of_template_insertion_modes[] = WP_HTML_Processor_State::INSERTION_MODE_IN_BODY;
			$this->state->insertion_mode                      = WP_HTML_Processor_State::INSERTION_MODE_IN_BODY;
			return $this->step( self::REPROCESS_CURRENT_NODE );
		}

		/*
		 * > Any other end tag
		 */
		if ( $is_closer ) {
			// Parse error: ignore the token.
			return $this->step();
		}

		/*
		 * > An end-of-file token
		 */
		if ( ! $this->state->stack_of_open_elements->contains( 'TEMPLATE' ) ) {
			// Stop parsing.
			return false;
		}

		// @todo Indicate a parse error once it's possible.
		$this->state->stack_of_open_elements->pop_until( 'TEMPLATE' );
		$this->state->active_formatting_elements->clear_up_to_last_marker();
		array_pop( $this->state->stack_of_template_insertion_modes );
		$this->reset_insertion_mode_appropriately();
		return $this->step( self::REPROCESS_CURRENT_NODE );
	}

	/**
	 * Parses next element in the 'after body' insertion mode.
	 *
	 * This internal function performs the 'after body' insertion mode
	 * logic for the generalized WP_HTML_Processor::step() function.
	 *
	 * @since 6.7.0 Stub implementation.
	 *
	 * @throws WP_HTML_Unsupported_Exception When encountering unsupported HTML input.
	 *
	 * @see https://html.spec.whatwg.org/#parsing-main-afterbody
	 * @see WP_HTML_Processor::step
	 *
	 * @return bool Whether an element was found.
	 */
	private function step_after_body(): bool {
		$tag_name   = $this->get_token_name();
		$token_type = $this->get_token_type();
		$op_sigil   = '#tag' === $token_type ? ( $this->is_tag_closer() ? '-' : '+' ) : '';
		$op         = "{$op_sigil}{$tag_name}";

		switch ( $op ) {
			/*
			 * > A character token that is one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF),
			 * >   U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE
			 *
			 * > Process the token using the rules for the "in body" insertion mode.
			 */
			case '#text':
				if ( parent::TEXT_IS_WHITESPACE === $this->text_node_classification ) {
					return $this->step_in_body();
				}
				goto after_body_anything_else;
				break;

			/*
			 * > A comment token
			 */
			case '#comment':
			case '#funky-comment':
			case '#presumptuous-tag':
				$this->bail( 'Content outside of BODY is unsupported.' );
				break;

			/*
			 * > A DOCTYPE token
			 */
			case 'html':
				// Parse error: ignore the token.
				return $this->step();

			/*
			 * > A start tag whose tag name is "html"
			 */
			case '+HTML':
				return $this->step_in_body();

			/*
			 * > An end tag whose tag name is "html"
			 *
			 * > If the parser was created as part of the HTML fragment parsing algorithm,
			 * > this is a parse error; ignore the token. (fragment case)
			 * >
			 * > Otherwise, switch the insertion mode to "after after body".
			 */
			case '-HTML':
				if ( isset( $this->context_node ) ) {
					return $this->step();
				}

				$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_AFTER_AFTER_BODY;
				return true;
		}

		/*
		 * > Parse error. Switch the insertion mode to "in body" and reprocess the token.
		 */
		after_body_anything_else:
		$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_BODY;
		return $this->step( self::REPROCESS_CURRENT_NODE );
	}

	/**
	 * Parses next element in the 'in frameset' insertion mode.
	 *
	 * This internal function performs the 'in frameset' insertion mode
	 * logic for the generalized WP_HTML_Processor::step() function.
	 *
	 * @since 6.7.0 Stub implementation.
	 *
	 * @throws WP_HTML_Unsupported_Exception When encountering unsupported HTML input.
	 *
	 * @see https://html.spec.whatwg.org/#parsing-main-inframeset
	 * @see WP_HTML_Processor::step
	 *
	 * @return bool Whether an element was found.
	 */
	private function step_in_frameset(): bool {
		$tag_name   = $this->get_token_name();
		$token_type = $this->get_token_type();
		$op_sigil   = '#tag' === $token_type ? ( $this->is_tag_closer() ? '-' : '+' ) : '';
		$op         = "{$op_sigil}{$tag_name}";

		switch ( $op ) {
			/*
			 * > A character token that is one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF),
			 * >   U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE
			 * >
			 * > Insert the character.
			 *
			 * This algorithm effectively strips non-whitespace characters from text and inserts
			 * them under HTML. This is not supported at this time.
			 */
			case '#text':
				if ( parent::TEXT_IS_WHITESPACE === $this->text_node_classification ) {
					return $this->step_in_body();
				}
				$this->bail( 'Non-whitespace characters cannot be handled in frameset.' );
				break;

			/*
			 * > A comment token
			 */
			case '#comment':
			case '#funky-comment':
			case '#presumptuous-tag':
				$this->insert_html_element( $this->state->current_token );
				return true;

			/*
			 * > A DOCTYPE token
			 */
			case 'html':
				// Parse error: ignore the token.
				return $this->step();

			/*
			 * > A start tag whose tag name is "html"
			 */
			case '+HTML':
				return $this->step_in_body();

			/*
			 * > A start tag whose tag name is "frameset"
			 */
			case '+FRAMESET':
				$this->insert_html_element( $this->state->current_token );
				return true;

			/*
			 * > An end tag whose tag name is "frameset"
			 */
			case '-FRAMESET':
				/*
				 * > If the current node is the root html element, then this is a parse error;
				 * > ignore the token. (fragment case)
				 */
				if ( $this->state->stack_of_open_elements->current_node_is( 'HTML' ) ) {
					return $this->step();
				}

				/*
				 * > Otherwise, pop the current node from the stack of open elements.
				 */
				$this->state->stack_of_open_elements->pop();

				/*
				 * > If the parser was not created as part of the HTML fragment parsing algorithm
				 * > (fragment case), and the current node is no longer a frameset element, then
				 * > switch the insertion mode to "after frameset".
				 */
				if ( ! isset( $this->context_node ) && ! $this->state->stack_of_open_elements->current_node_is( 'FRAMESET' ) ) {
					$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_AFTER_FRAMESET;
				}

				return true;

			/*
			 * > A start tag whose tag name is "frame"
			 *
			 * > Insert an HTML element for the token. Immediately pop the
			 * > current node off the stack of open elements.
			 * >
			 * > Acknowledge the token's self-closing flag, if it is set.
			 */
			case '+FRAME':
				$this->insert_html_element( $this->state->current_token );
				$this->state->stack_of_open_elements->pop();
				return true;

			/*
			 * > A start tag whose tag name is "noframes"
			 */
			case '+NOFRAMES':
				return $this->step_in_head();
		}

		// Parse error: ignore the token.
		return $this->step();
	}

	/**
	 * Parses next element in the 'after frameset' insertion mode.
	 *
	 * This internal function performs the 'after frameset' insertion mode
	 * logic for the generalized WP_HTML_Processor::step() function.
	 *
	 * @since 6.7.0 Stub implementation.
	 *
	 * @throws WP_HTML_Unsupported_Exception When encountering unsupported HTML input.
	 *
	 * @see https://html.spec.whatwg.org/#parsing-main-afterframeset
	 * @see WP_HTML_Processor::step
	 *
	 * @return bool Whether an element was found.
	 */
	private function step_after_frameset(): bool {
		$tag_name   = $this->get_token_name();
		$token_type = $this->get_token_type();
		$op_sigil   = '#tag' === $token_type ? ( $this->is_tag_closer() ? '-' : '+' ) : '';
		$op         = "{$op_sigil}{$tag_name}";

		switch ( $op ) {
			/*
			 * > A character token that is one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF),
			 * >   U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE
			 * >
			 * > Insert the character.
			 *
			 * This algorithm effectively strips non-whitespace characters from text and inserts
			 * them under HTML. This is not supported at this time.
			 */
			case '#text':
				if ( parent::TEXT_IS_WHITESPACE === $this->text_node_classification ) {
					return $this->step_in_body();
				}
				$this->bail( 'Non-whitespace characters cannot be handled in after frameset' );
				break;

			/*
			 * > A comment token
			 */
			case '#comment':
			case '#funky-comment':
			case '#presumptuous-tag':
				$this->insert_html_element( $this->state->current_token );
				return true;

			/*
			 * > A DOCTYPE token
			 */
			case 'html':
				// Parse error: ignore the token.
				return $this->step();

			/*
			 * > A start tag whose tag name is "html"
			 */
			case '+HTML':
				return $this->step_in_body();

			/*
			 * > An end tag whose tag name is "html"
			 */
			case '-HTML':
				$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_AFTER_AFTER_FRAMESET;
				return true;

			/*
			 * > A start tag whose tag name is "noframes"
			 */
			case '+NOFRAMES':
				return $this->step_in_head();
		}

		// Parse error: ignore the token.
		return $this->step();
	}

	/**
	 * Parses next element in the 'after after body' insertion mode.
	 *
	 * This internal function performs the 'after after body' insertion mode
	 * logic for the generalized WP_HTML_Processor::step() function.
	 *
	 * @since 6.7.0 Stub implementation.
	 *
	 * @throws WP_HTML_Unsupported_Exception When encountering unsupported HTML input.
	 *
	 * @see https://html.spec.whatwg.org/#the-after-after-body-insertion-mode
	 * @see WP_HTML_Processor::step
	 *
	 * @return bool Whether an element was found.
	 */
	private function step_after_after_body(): bool {
		$tag_name   = $this->get_token_name();
		$token_type = $this->get_token_type();
		$op_sigil   = '#tag' === $token_type ? ( $this->is_tag_closer() ? '-' : '+' ) : '';
		$op         = "{$op_sigil}{$tag_name}";

		switch ( $op ) {
			/*
			 * > A comment token
			 */
			case '#comment':
			case '#funky-comment':
			case '#presumptuous-tag':
				$this->bail( 'Content outside of HTML is unsupported.' );
				break;

			/*
			 * > A DOCTYPE token
			 * > A start tag whose tag name is "html"
			 *
			 * > Process the token using the rules for the "in body" insertion mode.
			 */
			case 'html':
			case '+HTML':
				return $this->step_in_body();

			/*
			 * > A character token that is one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF),
			 * >   U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE
			 * >
			 * > Process the token using the rules for the "in body" insertion mode.
			 */
			case '#text':
				if ( parent::TEXT_IS_WHITESPACE === $this->text_node_classification ) {
					return $this->step_in_body();
				}
				goto after_after_body_anything_else;
				break;
		}

		/*
		 * > Parse error. Switch the insertion mode to "in body" and reprocess the token.
		 */
		after_after_body_anything_else:
		$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_BODY;
		return $this->step( self::REPROCESS_CURRENT_NODE );
	}

	/**
	 * Parses next element in the 'after after frameset' insertion mode.
	 *
	 * This internal function performs the 'after after frameset' insertion mode
	 * logic for the generalized WP_HTML_Processor::step() function.
	 *
	 * @since 6.7.0 Stub implementation.
	 *
	 * @throws WP_HTML_Unsupported_Exception When encountering unsupported HTML input.
	 *
	 * @see https://html.spec.whatwg.org/#the-after-after-frameset-insertion-mode
	 * @see WP_HTML_Processor::step
	 *
	 * @return bool Whether an element was found.
	 */
	private function step_after_after_frameset(): bool {
		$tag_name   = $this->get_token_name();
		$token_type = $this->get_token_type();
		$op_sigil   = '#tag' === $token_type ? ( $this->is_tag_closer() ? '-' : '+' ) : '';
		$op         = "{$op_sigil}{$tag_name}";

		switch ( $op ) {
			/*
			 * > A comment token
			 */
			case '#comment':
			case '#funky-comment':
			case '#presumptuous-tag':
				$this->bail( 'Content outside of HTML is unsupported.' );
				break;

			/*
			 * > A DOCTYPE token
			 * > A start tag whose tag name is "html"
			 *
			 * > Process the token using the rules for the "in body" insertion mode.
			 */
			case 'html':
			case '+HTML':
				return $this->step_in_body();

			/*
			 * > A character token that is one of U+0009 CHARACTER TABULATION, U+000A LINE FEED (LF),
			 * >   U+000C FORM FEED (FF), U+000D CARRIAGE RETURN (CR), or U+0020 SPACE
			 * >
			 * > Process the token using the rules for the "in body" insertion mode.
			 *
			 * This algorithm effectively strips non-whitespace characters from text and inserts
			 * them under HTML. This is not supported at this time.
			 */
			case '#text':
				if ( parent::TEXT_IS_WHITESPACE === $this->text_node_classification ) {
					return $this->step_in_body();
				}
				$this->bail( 'Non-whitespace characters cannot be handled in after after frameset.' );
				break;

			/*
			 * > A start tag whose tag name is "noframes"
			 */
			case '+NOFRAMES':
				return $this->step_in_head();
		}

		// Parse error: ignore the token.
		return $this->step();
	}

	/**
	 * Parses next element in the 'in foreign content' insertion mode.
	 *
	 * This internal function performs the 'in foreign content' insertion mode
	 * logic for the generalized WP_HTML_Processor::step() function.
	 *
	 * @since 6.7.0 Stub implementation.
	 *
	 * @throws WP_HTML_Unsupported_Exception When encountering unsupported HTML input.
	 *
	 * @see https://html.spec.whatwg.org/#parsing-main-inforeign
	 * @see WP_HTML_Processor::step
	 *
	 * @return bool Whether an element was found.
	 */
	private function step_in_foreign_content(): bool {
		$tag_name   = $this->get_token_name();
		$token_type = $this->get_token_type();
		$op_sigil   = '#tag' === $token_type ? ( $this->is_tag_closer() ? '-' : '+' ) : '';
		$op         = "{$op_sigil}{$tag_name}";

		/*
		 * > A start tag whose name is "font", if the token has any attributes named "color", "face", or "size"
		 *
		 * This section drawn out above the switch to more easily incorporate
		 * the additional rules based on the presence of the attributes.
		 */
		if (
			'+FONT' === $op &&
			(
				null !== $this->get_attribute( 'color' ) ||
				null !== $this->get_attribute( 'face' ) ||
				null !== $this->get_attribute( 'size' )
			)
		) {
			$op = '+FONT with attributes';
		}

		switch ( $op ) {
			case '#text':
				/*
				 * > A character token that is U+0000 NULL
				 *
				 * This is handled by `get_modifiable_text()`.
				 */

				/*
				 * Whitespace-only text does not affect the frameset-ok flag.
				 * It is probably inter-element whitespace, but it may also
				 * contain character references which decode only to whitespace.
				 */
				if ( parent::TEXT_IS_GENERIC === $this->text_node_classification ) {
					$this->state->frameset_ok = false;
				}

				$this->insert_foreign_element( $this->state->current_token, false );
				return true;

			/*
			 * CDATA sections are alternate wrappers for text content and therefore
			 * ought to follow the same rules as text nodes.
			 */
			case '#cdata-section':
				/*
				 * NULL bytes and whitespace do not change the frameset-ok flag.
				 */
				$current_token        = $this->bookmarks[ $this->state->current_token->bookmark_name ];
				$cdata_content_start  = $current_token->start + 9;
				$cdata_content_length = $current_token->length - 12;
				if ( strspn( $this->html, "\0 \t\n\f\r", $cdata_content_start, $cdata_content_length ) !== $cdata_content_length ) {
					$this->state->frameset_ok = false;
				}

				$this->insert_foreign_element( $this->state->current_token, false );
				return true;

			/*
			 * > A comment token
			 */
			case '#comment':
			case '#funky-comment':
			case '#presumptuous-tag':
				$this->insert_foreign_element( $this->state->current_token, false );
				return true;

			/*
			 * > A DOCTYPE token
			 */
			case 'html':
				// Parse error: ignore the token.
				return $this->step();

			/*
			 * > A start tag whose tag name is "b", "big", "blockquote", "body", "br", "center",
			 * > "code", "dd", "div", "dl", "dt", "em", "embed", "h1", "h2", "h3", "h4", "h5",
			 * > "h6", "head", "hr", "i", "img", "li", "listing", "menu", "meta", "nobr", "ol",
			 * > "p", "pre", "ruby", "s", "small", "span", "strong", "strike", "sub", "sup",
			 * > "table", "tt", "u", "ul", "var"
			 *
			 * > A start tag whose name is "font", if the token has any attributes named "color", "face", or "size"
			 *
			 * > An end tag whose tag name is "br", "p"
			 *
			 * Closing BR tags are always reported by the Tag Processor as opening tags.
			 */
			case '+B':
			case '+BIG':
			case '+BLOCKQUOTE':
			case '+BODY':
			case '+BR':
			case '+CENTER':
			case '+CODE':
			case '+DD':
			case '+DIV':
			case '+DL':
			case '+DT':
			case '+EM':
			case '+EMBED':
			case '+H1':
			case '+H2':
			case '+H3':
			case '+H4':
			case '+H5':
			case '+H6':
			case '+HEAD':
			case '+HR':
			case '+I':
			case '+IMG':
			case '+LI':
			case '+LISTING':
			case '+MENU':
			case '+META':
			case '+NOBR':
			case '+OL':
			case '+P':
			case '+PRE':
			case '+RUBY':
			case '+S':
			case '+SMALL':
			case '+SPAN':
			case '+STRONG':
			case '+STRIKE':
			case '+SUB':
			case '+SUP':
			case '+TABLE':
			case '+TT':
			case '+U':
			case '+UL':
			case '+VAR':
			case '+FONT with attributes':
			case '-BR':
			case '-P':
				// @todo Indicate a parse error once it's possible.
				foreach ( $this->state->stack_of_open_elements->walk_up() as $current_node ) {
					if (
						'math' === $current_node->integration_node_type ||
						'html' === $current_node->integration_node_type ||
						'html' === $current_node->namespace
					) {
						break;
					}

					$this->state->stack_of_open_elements->pop();
				}
				goto in_foreign_content_process_in_current_insertion_mode;
		}

		/*
		 * > Any other start tag
		 */
		if ( ! $this->is_tag_closer() ) {
			$this->insert_foreign_element( $this->state->current_token, false );

			/*
			 * > If the token has its self-closing flag set, then run
			 * > the appropriate steps from the following list:
			 * >
			 * >   ↪ the token's tag name is "script", and the new current node is in the SVG namespace
			 * >         Acknowledge the token's self-closing flag, and then act as
			 * >         described in the steps for a "script" end tag below.
			 * >
			 * >   ↪ Otherwise
			 * >         Pop the current node off the stack of open elements and
			 * >         acknowledge the token's self-closing flag.
			 *
			 * Since the rules for SCRIPT below indicate to pop the element off of the stack of
			 * open elements, which is the same for the Otherwise condition, there's no need to
			 * separate these checks. The difference comes when a parser operates with the scripting
			 * flag enabled, and executes the script, which this parser does not support.
			 */
			if ( $this->state->current_token->has_self_closing_flag ) {
				$this->state->stack_of_open_elements->pop();
			}
			return true;
		}

		/*
		 * > An end tag whose name is "script", if the current node is an SVG script element.
		 */
		if ( $this->is_tag_closer() && 'SCRIPT' === $this->state->current_token->node_name && 'svg' === $this->state->current_token->namespace ) {
			$this->state->stack_of_open_elements->pop();
			return true;
		}

		/*
		 * > Any other end tag
		 */
		if ( $this->is_tag_closer() ) {
			$node = $this->state->stack_of_open_elements->current_node();
			if ( $tag_name !== $node->node_name ) {
				// @todo Indicate a parse error once it's possible.
			}
			in_foreign_content_end_tag_loop:
			if ( $node === $this->state->stack_of_open_elements->at( 1 ) ) {
				return true;
			}

			/*
			 * > If node's tag name, converted to ASCII lowercase, is the same as the tag name
			 * > of the token, pop elements from the stack of open elements until node has
			 * > been popped from the stack, and then return.
			 */
			if ( 0 === strcasecmp( $node->node_name, $tag_name ) ) {
				foreach ( $this->state->stack_of_open_elements->walk_up() as $item ) {
					$this->state->stack_of_open_elements->pop();
					if ( $node === $item ) {
						return true;
					}
				}
			}

			foreach ( $this->state->stack_of_open_elements->walk_up( $node ) as $item ) {
				$node = $item;
				break;
			}

			if ( 'html' !== $node->namespace ) {
				goto in_foreign_content_end_tag_loop;
			}

			in_foreign_content_process_in_current_insertion_mode:
			switch ( $this->state->insertion_mode ) {
				case WP_HTML_Processor_State::INSERTION_MODE_INITIAL:
					return $this->step_initial();

				case WP_HTML_Processor_State::INSERTION_MODE_BEFORE_HTML:
					return $this->step_before_html();

				case WP_HTML_Processor_State::INSERTION_MODE_BEFORE_HEAD:
					return $this->step_before_head();

				case WP_HTML_Processor_State::INSERTION_MODE_IN_HEAD:
					return $this->step_in_head();

				case WP_HTML_Processor_State::INSERTION_MODE_IN_HEAD_NOSCRIPT:
					return $this->step_in_head_noscript();

				case WP_HTML_Processor_State::INSERTION_MODE_AFTER_HEAD:
					return $this->step_after_head();

				case WP_HTML_Processor_State::INSERTION_MODE_IN_BODY:
					return $this->step_in_body();

				case WP_HTML_Processor_State::INSERTION_MODE_IN_TABLE:
					return $this->step_in_table();

				case WP_HTML_Processor_State::INSERTION_MODE_IN_TABLE_TEXT:
					return $this->step_in_table_text();

				case WP_HTML_Processor_State::INSERTION_MODE_IN_CAPTION:
					return $this->step_in_caption();

				case WP_HTML_Processor_State::INSERTION_MODE_IN_COLUMN_GROUP:
					return $this->step_in_column_group();

				case WP_HTML_Processor_State::INSERTION_MODE_IN_TABLE_BODY:
					return $this->step_in_table_body();

				case WP_HTML_Processor_State::INSERTION_MODE_IN_ROW:
					return $this->step_in_row();

				case WP_HTML_Processor_State::INSERTION_MODE_IN_CELL:
					return $this->step_in_cell();

				case WP_HTML_Processor_State::INSERTION_MODE_IN_SELECT:
					return $this->step_in_select();

				case WP_HTML_Processor_State::INSERTION_MODE_IN_SELECT_IN_TABLE:
					return $this->step_in_select_in_table();

				case WP_HTML_Processor_State::INSERTION_MODE_IN_TEMPLATE:
					return $this->step_in_template();

				case WP_HTML_Processor_State::INSERTION_MODE_AFTER_BODY:
					return $this->step_after_body();

				case WP_HTML_Processor_State::INSERTION_MODE_IN_FRAMESET:
					return $this->step_in_frameset();

				case WP_HTML_Processor_State::INSERTION_MODE_AFTER_FRAMESET:
					return $this->step_after_frameset();

				case WP_HTML_Processor_State::INSERTION_MODE_AFTER_AFTER_BODY:
					return $this->step_after_after_body();

				case WP_HTML_Processor_State::INSERTION_MODE_AFTER_AFTER_FRAMESET:
					return $this->step_after_after_frameset();

				// This should be unreachable but PHP doesn't have total type checking on switch.
				default:
					$this->bail( "Unaware of the requested parsing mode: '{$this->state->insertion_mode}'." );
			}
		}

		$this->bail( 'Should not have been able to reach end of IN FOREIGN CONTENT processing. Check HTML API code.' );
		// This unnecessary return prevents tools from inaccurately reporting type errors.
		return false;
	}

	/*
	 * Internal helpers
	 */

	/**
	 * Creates a new bookmark for the currently-matched token and returns the generated name.
	 *
	 * @since 6.4.0
	 * @since 6.5.0 Renamed from bookmark_tag() to bookmark_token().
	 *
	 * @throws Exception When unable to allocate requested bookmark.
	 *
	 * @return string|false Name of created bookmark, or false if unable to create.
	 */
	private function bookmark_token() {
		if ( ! parent::set_bookmark( ++$this->bookmark_counter ) ) {
			$this->last_error = self::ERROR_EXCEEDED_MAX_BOOKMARKS;
			throw new Exception( 'could not allocate bookmark' );
		}

		return "{$this->bookmark_counter}";
	}

	/*
	 * HTML semantic overrides for Tag Processor
	 */

	/**
	 * Indicates the namespace of the current token, or "html" if there is none.
	 *
	 * @return string One of "html", "math", or "svg".
	 */
	public function get_namespace(): string {
		if ( ! isset( $this->current_element ) ) {
			return parent::get_namespace();
		}

		return $this->current_element->token->namespace;
	}

	/**
	 * Returns the uppercase name of the matched tag.
	 *
	 * The semantic rules for HTML specify that certain tags be reprocessed
	 * with a different tag name. Because of this, the tag name presented
	 * by the HTML Processor may differ from the one reported by the HTML
	 * Tag Processor, which doesn't apply these semantic rules.
	 *
	 * Example:
	 *
	 *     $processor = new WP_HTML_Tag_Processor( '<div class="test">Test</div>' );
	 *     $processor->next_tag() === true;
	 *     $processor->get_tag() === 'DIV';
	 *
	 *     $processor->next_tag() === false;
	 *     $processor->get_tag() === null;
	 *
	 * @since 6.4.0
	 *
	 * @return string|null Name of currently matched tag in input HTML, or `null` if none found.
	 */
	public function get_tag(): ?string {
		if ( null !== $this->last_error ) {
			return null;
		}

		if ( $this->is_virtual() ) {
			return $this->current_element->token->node_name;
		}

		$tag_name = parent::get_tag();

		/*
		 * > A start tag whose tag name is "image"
		 * > Change the token's tag name to "img" and reprocess it. (Don't ask.)
		 */
		return ( 'IMAGE' === $tag_name && 'html' === $this->get_namespace() )
			? 'IMG'
			: $tag_name;
	}

	/**
	 * Indicates if the currently matched tag contains the self-closing flag.
	 *
	 * No HTML elements ought to have the self-closing flag and for those, the self-closing
	 * flag will be ignored. For void elements this is benign because they "self close"
	 * automatically. For non-void HTML elements though problems will appear if someone
	 * intends to use a self-closing element in place of that element with an empty body.
	 * For HTML foreign elements and custom elements the self-closing flag determines if
	 * they self-close or not.
	 *
	 * This function does not determine if a tag is self-closing,
	 * but only if the self-closing flag is present in the syntax.
	 *
	 * @since 6.6.0 Subclassed for the HTML Processor.
	 *
	 * @return bool Whether the currently matched tag contains the self-closing flag.
	 */
	public function has_self_closing_flag(): bool {
		return $this->is_virtual() ? false : parent::has_self_closing_flag();
	}

	/**
	 * Returns the node name represented by the token.
	 *
	 * This matches the DOM API value `nodeName`. Some values
	 * are static, such as `#text` for a text node, while others
	 * are dynamically generated from the token itself.
	 *
	 * Dynamic names:
	 *  - Uppercase tag name for tag matches.
	 *  - `html` for DOCTYPE declarations.
	 *
	 * Note that if the Tag Processor is not matched on a token
	 * then this function will return `null`, either because it
	 * hasn't yet found a token or because it reached the end
	 * of the document without matching a token.
	 *
	 * @since 6.6.0 Subclassed for the HTML Processor.
	 *
	 * @return string|null Name of the matched token.
	 */
	public function get_token_name(): ?string {
		return $this->is_virtual()
			? $this->current_element->token->node_name
			: parent::get_token_name();
	}

	/**
	 * Indicates the kind of matched token, if any.
	 *
	 * This differs from `get_token_name()` in that it always
	 * returns a static string indicating the type, whereas
	 * `get_token_name()` may return values derived from the
	 * token itself, such as a tag name or processing
	 * instruction tag.
	 *
	 * Possible values:
	 *  - `#tag` when matched on a tag.
	 *  - `#text` when matched on a text node.
	 *  - `#cdata-section` when matched on a CDATA node.
	 *  - `#comment` when matched on a comment.
	 *  - `#doctype` when matched on a DOCTYPE declaration.
	 *  - `#presumptuous-tag` when matched on an empty tag closer.
	 *  - `#funky-comment` when matched on a funky comment.
	 *
	 * @since 6.6.0 Subclassed for the HTML Processor.
	 *
	 * @return string|null What kind of token is matched, or null.
	 */
	public function get_token_type(): ?string {
		if ( $this->is_virtual() ) {
			/*
			 * This logic comes from the Tag Processor.
			 *
			 * @todo It would be ideal not to repeat this here, but it's not clearly
			 *       better to allow passing a token name to `get_token_type()`.
			 */
			$node_name     = $this->current_element->token->node_name;
			$starting_char = $node_name[0];
			if ( 'A' <= $starting_char && 'Z' >= $starting_char ) {
				return '#tag';
			}

			if ( 'html' === $node_name ) {
				return '#doctype';
			}

			return $node_name;
		}

		return parent::get_token_type();
	}

	/**
	 * Returns the value of a requested attribute from a matched tag opener if that attribute exists.
	 *
	 * Example:
	 *
	 *     $p = WP_HTML_Processor::create_fragment( '<div enabled class="test" data-test-id="14">Test</div>' );
	 *     $p->next_token() === true;
	 *     $p->get_attribute( 'data-test-id' ) === '14';
	 *     $p->get_attribute( 'enabled' ) === true;
	 *     $p->get_attribute( 'aria-label' ) === null;
	 *
	 *     $p->next_tag() === false;
	 *     $p->get_attribute( 'class' ) === null;
	 *
	 * @since 6.6.0 Subclassed for HTML Processor.
	 *
	 * @param string $name Name of attribute whose value is requested.
	 * @return string|true|null Value of attribute or `null` if not available. Boolean attributes return `true`.
	 */
	public function get_attribute( $name ) {
		return $this->is_virtual() ? null : parent::get_attribute( $name );
	}

	/**
	 * Updates or creates a new attribute on the currently matched tag with the passed value.
	 *
	 * For boolean attributes special handling is provided:
	 *  - When `true` is passed as the value, then only the attribute name is added to the tag.
	 *  - When `false` is passed, the attribute gets removed if it existed before.
	 *
	 * For string attributes, the value is escaped using the `esc_attr` function.
	 *
	 * @since 6.6.0 Subclassed for the HTML Processor.
	 *
	 * @param string      $name  The attribute name to target.
	 * @param string|bool $value The new attribute value.
	 * @return bool Whether an attribute value was set.
	 */
	public function set_attribute( $name, $value ): bool {
		return $this->is_virtual() ? false : parent::set_attribute( $name, $value );
	}

	/**
	 * Remove an attribute from the currently-matched tag.
	 *
	 * @since 6.6.0 Subclassed for HTML Processor.
	 *
	 * @param string $name The attribute name to remove.
	 * @return bool Whether an attribute was removed.
	 */
	public function remove_attribute( $name ): bool {
		return $this->is_virtual() ? false : parent::remove_attribute( $name );
	}

	/**
	 * Gets lowercase names of all attributes matching a given prefix in the current tag.
	 *
	 * Note that matching is case-insensitive. This is in accordance with the spec:
	 *
	 * > There must never be two or more attributes on
	 * > the same start tag whose names are an ASCII
	 * > case-insensitive match for each other.
	 *     - HTML 5 spec
	 *
	 * Example:
	 *
	 *     $p = new WP_HTML_Tag_Processor( '<div data-ENABLED class="test" DATA-test-id="14">Test</div>' );
	 *     $p->next_tag( array( 'class_name' => 'test' ) ) === true;
	 *     $p->get_attribute_names_with_prefix( 'data-' ) === array( 'data-enabled', 'data-test-id' );
	 *
	 *     $p->next_tag() === false;
	 *     $p->get_attribute_names_with_prefix( 'data-' ) === null;
	 *
	 * @since 6.6.0 Subclassed for the HTML Processor.
	 *
	 * @see https://html.spec.whatwg.org/multipage/syntax.html#attributes-2:ascii-case-insensitive
	 *
	 * @param string $prefix Prefix of requested attribute names.
	 * @return array|null List of attribute names, or `null` when no tag opener is matched.
	 */
	public function get_attribute_names_with_prefix( $prefix ): ?array {
		return $this->is_virtual() ? null : parent::get_attribute_names_with_prefix( $prefix );
	}

	/**
	 * Adds a new class name to the currently matched tag.
	 *
	 * @since 6.6.0 Subclassed for the HTML Processor.
	 *
	 * @param string $class_name The class name to add.
	 * @return bool Whether the class was set to be added.
	 */
	public function add_class( $class_name ): bool {
		return $this->is_virtual() ? false : parent::add_class( $class_name );
	}

	/**
	 * Removes a class name from the currently matched tag.
	 *
	 * @since 6.6.0 Subclassed for the HTML Processor.
	 *
	 * @param string $class_name The class name to remove.
	 * @return bool Whether the class was set to be removed.
	 */
	public function remove_class( $class_name ): bool {
		return $this->is_virtual() ? false : parent::remove_class( $class_name );
	}

	/**
	 * Returns if a matched tag contains the given ASCII case-insensitive class name.
	 *
	 * @since 6.6.0 Subclassed for the HTML Processor.
	 *
	 * @todo When reconstructing active formatting elements with attributes, find a way
	 *       to indicate if the virtually-reconstructed formatting elements contain the
	 *       wanted class name.
	 *
	 * @param string $wanted_class Look for this CSS class name, ASCII case-insensitive.
	 * @return bool|null Whether the matched tag contains the given class name, or null if not matched.
	 */
	public function has_class( $wanted_class ): ?bool {
		return $this->is_virtual() ? null : parent::has_class( $wanted_class );
	}

	/**
	 * Generator for a foreach loop to step through each class name for the matched tag.
	 *
	 * This generator function is designed to be used inside a "foreach" loop.
	 *
	 * Example:
	 *
	 *     $p = WP_HTML_Processor::create_fragment( "<div class='free &lt;egg&lt;\tlang-en'>" );
	 *     $p->next_tag();
	 *     foreach ( $p->class_list() as $class_name ) {
	 *         echo "{$class_name} ";
	 *     }
	 *     // Outputs: "free <egg> lang-en "
	 *
	 * @since 6.6.0 Subclassed for the HTML Processor.
	 */
	public function class_list() {
		return $this->is_virtual() ? null : parent::class_list();
	}

	/**
	 * Returns the modifiable text for a matched token, or an empty string.
	 *
	 * Modifiable text is text content that may be read and changed without
	 * changing the HTML structure of the document around it. This includes
	 * the contents of `#text` nodes in the HTML as well as the inner
	 * contents of HTML comments, Processing Instructions, and others, even
	 * though these nodes aren't part of a parsed DOM tree. They also contain
	 * the contents of SCRIPT and STYLE tags, of TEXTAREA tags, and of any
	 * other section in an HTML document which cannot contain HTML markup (DATA).
	 *
	 * If a token has no modifiable text then an empty string is returned to
	 * avoid needless crashing or type errors. An empty string does not mean
	 * that a token has modifiable text, and a token with modifiable text may
	 * have an empty string (e.g. a comment with no contents).
	 *
	 * @since 6.6.0 Subclassed for the HTML Processor.
	 *
	 * @return string
	 */
	public function get_modifiable_text(): string {
		return $this->is_virtual() ? '' : parent::get_modifiable_text();
	}

	/**
	 * Indicates what kind of comment produced the comment node.
	 *
	 * Because there are different kinds of HTML syntax which produce
	 * comments, the Tag Processor tracks and exposes this as a type
	 * for the comment. Nominally only regular HTML comments exist as
	 * they are commonly known, but a number of unrelated syntax errors
	 * also produce comments.
	 *
	 * @see self::COMMENT_AS_ABRUPTLY_CLOSED_COMMENT
	 * @see self::COMMENT_AS_CDATA_LOOKALIKE
	 * @see self::COMMENT_AS_INVALID_HTML
	 * @see self::COMMENT_AS_HTML_COMMENT
	 * @see self::COMMENT_AS_PI_NODE_LOOKALIKE
	 *
	 * @since 6.6.0 Subclassed for the HTML Processor.
	 *
	 * @return string|null
	 */
	public function get_comment_type(): ?string {
		return $this->is_virtual() ? null : parent::get_comment_type();
	}

	/**
	 * Removes a bookmark that is no longer needed.
	 *
	 * Releasing a bookmark frees up the small
	 * performance overhead it requires.
	 *
	 * @since 6.4.0
	 *
	 * @param string $bookmark_name Name of the bookmark to remove.
	 * @return bool Whether the bookmark already existed before removal.
	 */
	public function release_bookmark( $bookmark_name ): bool {
		return parent::release_bookmark( "_{$bookmark_name}" );
	}

	/**
	 * Moves the internal cursor in the HTML Processor to a given bookmark's location.
	 *
	 * Be careful! Seeking backwards to a previous location resets the parser to the
	 * start of the document and reparses the entire contents up until it finds the
	 * sought-after bookmarked location.
	 *
	 * In order to prevent accidental infinite loops, there's a
	 * maximum limit on the number of times seek() can be called.
	 *
	 * @throws Exception When unable to allocate a bookmark for the next token in the input HTML document.
	 *
	 * @since 6.4.0
	 *
	 * @param string $bookmark_name Jump to the place in the document identified by this bookmark name.
	 * @return bool Whether the internal cursor was successfully moved to the bookmark's location.
	 */
	public function seek( $bookmark_name ): bool {
		// Flush any pending updates to the document before beginning.
		$this->get_updated_html();

		$actual_bookmark_name = "_{$bookmark_name}";
		$processor_started_at = $this->state->current_token
			? $this->bookmarks[ $this->state->current_token->bookmark_name ]->start
			: 0;
		$bookmark_starts_at   = $this->bookmarks[ $actual_bookmark_name ]->start;
		$direction            = $bookmark_starts_at > $processor_started_at ? 'forward' : 'backward';

		/*
		 * If seeking backwards, it's possible that the sought-after bookmark exists within an element
		 * which has been closed before the current cursor; in other words, it has already been removed
		 * from the stack of open elements. This means that it's insufficient to simply pop off elements
		 * from the stack of open elements which appear after the bookmarked location and then jump to
		 * that location, as the elements which were open before won't be re-opened.
		 *
		 * In order to maintain consistency, the HTML Processor rewinds to the start of the document
		 * and reparses everything until it finds the sought-after bookmark.
		 *
		 * There are potentially better ways to do this: cache the parser state for each bookmark and
		 * restore it when seeking; store an immutable and idempotent register of where elements open
		 * and close.
		 *
		 * If caching the parser state it will be essential to properly maintain the cached stack of
		 * open elements and active formatting elements when modifying the document. This could be a
		 * tedious and time-consuming process as well, and so for now will not be performed.
		 *
		 * It may be possible to track bookmarks for where elements open and close, and in doing so
		 * be able to quickly recalculate breadcrumbs for any element in the document. It may even
		 * be possible to remove the stack of open elements and compute it on the fly this way.
		 * If doing this, the parser would need to track the opening and closing locations for all
		 * tokens in the breadcrumb path for any and all bookmarks. By utilizing bookmarks themselves
		 * this list could be automatically maintained while modifying the document. Finding the
		 * breadcrumbs would then amount to traversing that list from the start until the token
		 * being inspected. Once an element closes, if there are no bookmarks pointing to locations
		 * within that element, then all of these locations may be forgotten to save on memory use
		 * and computation time.
		 */
		if ( 'backward' === $direction ) {
			/*
			 * Instead of clearing the parser state and starting fresh, calling the stack methods
			 * maintains the proper flags in the parser.
			 */
			foreach ( $this->state->stack_of_open_elements->walk_up() as $item ) {
				if ( 'context-node' === $item->bookmark_name ) {
					break;
				}

				$this->state->stack_of_open_elements->remove_node( $item );
			}

			foreach ( $this->state->active_formatting_elements->walk_up() as $item ) {
				if ( 'context-node' === $item->bookmark_name ) {
					break;
				}

				$this->state->active_formatting_elements->remove_node( $item );
			}

			parent::seek( 'context-node' );
			$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_BODY;
			$this->state->frameset_ok    = true;
			$this->element_queue         = array();
			$this->current_element       = null;

			if ( isset( $this->context_node ) ) {
				$this->breadcrumbs = array_slice( $this->breadcrumbs, 0, 2 );
			} else {
				$this->breadcrumbs = array();
			}
		}

		// When moving forwards, reparse the document until reaching the same location as the original bookmark.
		if ( $bookmark_starts_at === $this->bookmarks[ $this->state->current_token->bookmark_name ]->start ) {
			return true;
		}

		while ( $this->next_token() ) {
			if ( $bookmark_starts_at === $this->bookmarks[ $this->state->current_token->bookmark_name ]->start ) {
				while ( isset( $this->current_element ) && WP_HTML_Stack_Event::POP === $this->current_element->operation ) {
					$this->current_element = array_shift( $this->element_queue );
				}
				return true;
			}
		}

		return false;
	}

	/**
	 * Sets a bookmark in the HTML document.
	 *
	 * Bookmarks represent specific places or tokens in the HTML
	 * document, such as a tag opener or closer. When applying
	 * edits to a document, such as setting an attribute, the
	 * text offsets of that token may shift; the bookmark is
	 * kept updated with those shifts and remains stable unless
	 * the entire span of text in which the token sits is removed.
	 *
	 * Release bookmarks when they are no longer needed.
	 *
	 * Example:
	 *
	 *     <main><h2>Surprising fact you may not know!</h2></main>
	 *           ^  ^
	 *            \-|-- this `H2` opener bookmark tracks the token
	 *
	 *     <main class="clickbait"><h2>Surprising fact you may no…
	 *                             ^  ^
	 *                              \-|-- it shifts with edits
	 *
	 * Bookmarks provide the ability to seek to a previously-scanned
	 * place in the HTML document. This avoids the need to re-scan
	 * the entire document.
	 *
	 * Example:
	 *
	 *     <ul><li>One</li><li>Two</li><li>Three</li></ul>
	 *                                 ^^^^
	 *                                 want to note this last item
	 *
	 *     $p = new WP_HTML_Tag_Processor( $html );
	 *     $in_list = false;
	 *     while ( $p->next_tag( array( 'tag_closers' => $in_list ? 'visit' : 'skip' ) ) ) {
	 *         if ( 'UL' === $p->get_tag() ) {
	 *             if ( $p->is_tag_closer() ) {
	 *                 $in_list = false;
	 *                 $p->set_bookmark( 'resume' );
	 *                 if ( $p->seek( 'last-li' ) ) {
	 *                     $p->add_class( 'last-li' );
	 *                 }
	 *                 $p->seek( 'resume' );
	 *                 $p->release_bookmark( 'last-li' );
	 *                 $p->release_bookmark( 'resume' );
	 *             } else {
	 *                 $in_list = true;
	 *             }
	 *         }
	 *
	 *         if ( 'LI' === $p->get_tag() ) {
	 *             $p->set_bookmark( 'last-li' );
	 *         }
	 *     }
	 *
	 * Bookmarks intentionally hide the internal string offsets
	 * to which they refer. They are maintained internally as
	 * updates are applied to the HTML document and therefore
	 * retain their "position" - the location to which they
	 * originally pointed. The inability to use bookmarks with
	 * functions like `substr` is therefore intentional to guard
	 * against accidentally breaking the HTML.
	 *
	 * Because bookmarks allocate memory and require processing
	 * for every applied update, they are limited and require
	 * a name. They should not be created with programmatically-made
	 * names, such as "li_{$index}" with some loop. As a general
	 * rule they should only be created with string-literal names
	 * like "start-of-section" or "last-paragraph".
	 *
	 * Bookmarks are a powerful tool to enable complicated behavior.
	 * Consider double-checking that you need this tool if you are
	 * reaching for it, as inappropriate use could lead to broken
	 * HTML structure or unwanted processing overhead.
	 *
	 * @since 6.4.0
	 *
	 * @param string $bookmark_name Identifies this particular bookmark.
	 * @return bool Whether the bookmark was successfully created.
	 */
	public function set_bookmark( $bookmark_name ): bool {
		return parent::set_bookmark( "_{$bookmark_name}" );
	}

	/**
	 * Checks whether a bookmark with the given name exists.
	 *
	 * @since 6.5.0
	 *
	 * @param string $bookmark_name Name to identify a bookmark that potentially exists.
	 * @return bool Whether that bookmark exists.
	 */
	public function has_bookmark( $bookmark_name ): bool {
		return parent::has_bookmark( "_{$bookmark_name}" );
	}

	/*
	 * HTML Parsing Algorithms
	 */

	/**
	 * Closes a P element.
	 *
	 * @since 6.4.0
	 *
	 * @throws WP_HTML_Unsupported_Exception When encountering unsupported HTML input.
	 *
	 * @see https://html.spec.whatwg.org/#close-a-p-element
	 */
	private function close_a_p_element(): void {
		$this->generate_implied_end_tags( 'P' );
		$this->state->stack_of_open_elements->pop_until( 'P' );
	}

	/**
	 * Closes elements that have implied end tags.
	 *
	 * @since 6.4.0
	 * @since 6.7.0 Full spec support.
	 *
	 * @see https://html.spec.whatwg.org/#generate-implied-end-tags
	 *
	 * @param string|null $except_for_this_element Perform as if this element doesn't exist in the stack of open elements.
	 */
	private function generate_implied_end_tags( ?string $except_for_this_element = null ): void {
		$elements_with_implied_end_tags = array(
			'DD',
			'DT',
			'LI',
			'OPTGROUP',
			'OPTION',
			'P',
			'RB',
			'RP',
			'RT',
			'RTC',
		);

		$no_exclusions = ! isset( $except_for_this_element );

		while (
			( $no_exclusions || ! $this->state->stack_of_open_elements->current_node_is( $except_for_this_element ) ) &&
			in_array( $this->state->stack_of_open_elements->current_node()->node_name, $elements_with_implied_end_tags, true )
		) {
			$this->state->stack_of_open_elements->pop();
		}
	}

	/**
	 * Closes elements that have implied end tags, thoroughly.
	 *
	 * See the HTML specification for an explanation why this is
	 * different from generating end tags in the normal sense.
	 *
	 * @since 6.4.0
	 * @since 6.7.0 Full spec support.
	 *
	 * @see WP_HTML_Processor::generate_implied_end_tags
	 * @see https://html.spec.whatwg.org/#generate-implied-end-tags
	 */
	private function generate_implied_end_tags_thoroughly(): void {
		$elements_with_implied_end_tags = array(
			'CAPTION',
			'COLGROUP',
			'DD',
			'DT',
			'LI',
			'OPTGROUP',
			'OPTION',
			'P',
			'RB',
			'RP',
			'RT',
			'RTC',
			'TBODY',
			'TD',
			'TFOOT',
			'TH',
			'THEAD',
			'TR',
		);

		while ( in_array( $this->state->stack_of_open_elements->current_node()->node_name, $elements_with_implied_end_tags, true ) ) {
			$this->state->stack_of_open_elements->pop();
		}
	}

	/**
	 * Returns the adjusted current node.
	 *
	 * > The adjusted current node is the context element if the parser was created as
	 * > part of the HTML fragment parsing algorithm and the stack of open elements
	 * > has only one element in it (fragment case); otherwise, the adjusted current
	 * > node is the current node.
	 *
	 * @see https://html.spec.whatwg.org/#adjusted-current-node
	 *
	 * @since 6.7.0
	 *
	 * @return WP_HTML_Token|null The adjusted current node.
	 */
	private function get_adjusted_current_node(): ?WP_HTML_Token {
		if ( isset( $this->context_node ) && 1 === $this->state->stack_of_open_elements->count() ) {
			return $this->context_node;
		}

		return $this->state->stack_of_open_elements->current_node();
	}

	/**
	 * Reconstructs the active formatting elements.
	 *
	 * > This has the effect of reopening all the formatting elements that were opened
	 * > in the current body, cell, or caption (whichever is youngest) that haven't
	 * > been explicitly closed.
	 *
	 * @since 6.4.0
	 *
	 * @throws WP_HTML_Unsupported_Exception When encountering unsupported HTML input.
	 *
	 * @see https://html.spec.whatwg.org/#reconstruct-the-active-formatting-elements
	 *
	 * @return bool Whether any formatting elements needed to be reconstructed.
	 */
	private function reconstruct_active_formatting_elements(): bool {
		/*
		 * > If there are no entries in the list of active formatting elements, then there is nothing
		 * > to reconstruct; stop this algorithm.
		 */
		if ( 0 === $this->state->active_formatting_elements->count() ) {
			return false;
		}

		$last_entry = $this->state->active_formatting_elements->current_node();
		if (

			/*
			 * > If the last (most recently added) entry in the list of active formatting elements is a marker;
			 * > stop this algorithm.
			 */
			'marker' === $last_entry->node_name ||

			/*
			 * > If the last (most recently added) entry in the list of active formatting elements is an
			 * > element that is in the stack of open elements, then there is nothing to reconstruct;
			 * > stop this algorithm.
			 */
			$this->state->stack_of_open_elements->contains_node( $last_entry )
		) {
			return false;
		}

		$this->bail( 'Cannot reconstruct active formatting elements when advancing and rewinding is required.' );
	}

	/**
	 * Runs the reset the insertion mode appropriately algorithm.
	 *
	 * @since 6.7.0
	 *
	 * @see https://html.spec.whatwg.org/multipage/parsing.html#reset-the-insertion-mode-appropriately
	 */
	private function reset_insertion_mode_appropriately(): void {
		// Set the first node.
		$first_node = null;
		foreach ( $this->state->stack_of_open_elements->walk_down() as $first_node ) {
			break;
		}

		/*
		 * > 1. Let _last_ be false.
		 */
		$last = false;
		foreach ( $this->state->stack_of_open_elements->walk_up() as $node ) {
			/*
			 * > 2. Let _node_ be the last node in the stack of open elements.
			 * > 3. _Loop_: If _node_ is the first node in the stack of open elements, then set _last_
			 * >            to true, and, if the parser was created as part of the HTML fragment parsing
			 * >            algorithm (fragment case), set node to the context element passed to
			 * >            that algorithm.
			 * > …
			 */
			if ( $node === $first_node ) {
				$last = true;
				if ( isset( $this->context_node ) ) {
					$node = $this->context_node;
				}
			}

			// All of the following rules are for matching HTML elements.
			if ( 'html' !== $node->namespace ) {
				continue;
			}

			switch ( $node->node_name ) {
				/*
				 * > 4. If node is a `select` element, run these substeps:
				 * >   1. If _last_ is true, jump to the step below labeled done.
				 * >   2. Let _ancestor_ be _node_.
				 * >   3. _Loop_: If _ancestor_ is the first node in the stack of open elements,
				 * >      jump to the step below labeled done.
				 * >   4. Let ancestor be the node before ancestor in the stack of open elements.
				 * >   …
				 * >   7. Jump back to the step labeled _loop_.
				 * >   8. _Done_: Switch the insertion mode to "in select" and return.
				 */
				case 'SELECT':
					if ( ! $last ) {
						foreach ( $this->state->stack_of_open_elements->walk_up( $node ) as $ancestor ) {
							if ( 'html' !== $ancestor->namespace ) {
								continue;
							}

							switch ( $ancestor->node_name ) {
								/*
								 * > 5. If _ancestor_ is a `template` node, jump to the step below
								 * >    labeled _done_.
								 */
								case 'TEMPLATE':
									break 2;

								/*
								 * > 6. If _ancestor_ is a `table` node, switch the insertion mode to
								 * >    "in select in table" and return.
								 */
								case 'TABLE':
									$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_SELECT_IN_TABLE;
									return;
							}
						}
					}
					$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_SELECT;
					return;

				/*
				 * > 5. If _node_ is a `td` or `th` element and _last_ is false, then switch the
				 * >    insertion mode to "in cell" and return.
				 */
				case 'TD':
				case 'TH':
					if ( ! $last ) {
						$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_CELL;
						return;
					}
					break;

					/*
					* > 6. If _node_ is a `tr` element, then switch the insertion mode to "in row"
					* >    and return.
					*/
				case 'TR':
					$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_ROW;
					return;

				/*
				 * > 7. If _node_ is a `tbody`, `thead`, or `tfoot` element, then switch the
				 * >    insertion mode to "in table body" and return.
				 */
				case 'TBODY':
				case 'THEAD':
				case 'TFOOT':
					$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_TABLE_BODY;
					return;

				/*
				 * > 8. If _node_ is a `caption` element, then switch the insertion mode to
				 * >    "in caption" and return.
				 */
				case 'CAPTION':
					$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_CAPTION;
					return;

				/*
				 * > 9. If _node_ is a `colgroup` element, then switch the insertion mode to
				 * >    "in column group" and return.
				 */
				case 'COLGROUP':
					$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_COLUMN_GROUP;
					return;

				/*
				 * > 10. If _node_ is a `table` element, then switch the insertion mode to
				 * >     "in table" and return.
				 */
				case 'TABLE':
					$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_TABLE;
					return;

				/*
				 * > 11. If _node_ is a `template` element, then switch the insertion mode to the
				 * >     current template insertion mode and return.
				 */
				case 'TEMPLATE':
					$this->state->insertion_mode = end( $this->state->stack_of_template_insertion_modes );
					return;

				/*
				 * > 12. If _node_ is a `head` element and _last_ is false, then switch the
				 * >     insertion mode to "in head" and return.
				 */
				case 'HEAD':
					if ( ! $last ) {
						$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_HEAD;
						return;
					}
					break;

				/*
				 * > 13. If _node_ is a `body` element, then switch the insertion mode to "in body"
				 * >     and return.
				 */
				case 'BODY':
					$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_BODY;
					return;

				/*
				 * > 14. If _node_ is a `frameset` element, then switch the insertion mode to
				 * >     "in frameset" and return. (fragment case)
				 */
				case 'FRAMESET':
					$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_FRAMESET;
					return;

				/*
				 * > 15. If _node_ is an `html` element, run these substeps:
				 * >     1. If the head element pointer is null, switch the insertion mode to
				 * >        "before head" and return. (fragment case)
				 * >     2. Otherwise, the head element pointer is not null, switch the insertion
				 * >        mode to "after head" and return.
				 */
				case 'HTML':
					$this->state->insertion_mode = isset( $this->state->head_element )
						? WP_HTML_Processor_State::INSERTION_MODE_AFTER_HEAD
						: WP_HTML_Processor_State::INSERTION_MODE_BEFORE_HEAD;
					return;
			}
		}

		/*
		 * > 16. If _last_ is true, then switch the insertion mode to "in body"
		 * >     and return. (fragment case)
		 *
		 * This is only reachable if `$last` is true, as per the fragment parsing case.
		 */
		$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_BODY;
	}

	/**
	 * Runs the adoption agency algorithm.
	 *
	 * @since 6.4.0
	 *
	 * @throws WP_HTML_Unsupported_Exception When encountering unsupported HTML input.
	 *
	 * @see https://html.spec.whatwg.org/#adoption-agency-algorithm
	 */
	private function run_adoption_agency_algorithm(): void {
		$budget       = 1000;
		$subject      = $this->get_tag();
		$current_node = $this->state->stack_of_open_elements->current_node();

		if (
			// > If the current node is an HTML element whose tag name is subject
			$current_node && $subject === $current_node->node_name &&
			// > the current node is not in the list of active formatting elements
			! $this->state->active_formatting_elements->contains_node( $current_node )
		) {
			$this->state->stack_of_open_elements->pop();
			return;
		}

		$outer_loop_counter = 0;
		while ( $budget-- > 0 ) {
			if ( $outer_loop_counter++ >= 8 ) {
				return;
			}

			/*
			 * > Let formatting element be the last element in the list of active formatting elements that:
			 * >   - is between the end of the list and the last marker in the list,
			 * >     if any, or the start of the list otherwise,
			 * >   - and has the tag name subject.
			 */
			$formatting_element = null;
			foreach ( $this->state->active_formatting_elements->walk_up() as $item ) {
				if ( 'marker' === $item->node_name ) {
					break;
				}

				if ( $subject === $item->node_name ) {
					$formatting_element = $item;
					break;
				}
			}

			// > If there is no such element, then return and instead act as described in the "any other end tag" entry above.
			if ( null === $formatting_element ) {
				$this->bail( 'Cannot run adoption agency when "any other end tag" is required.' );
			}

			// > If formatting element is not in the stack of open elements, then this is a parse error; remove the element from the list, and return.
			if ( ! $this->state->stack_of_open_elements->contains_node( $formatting_element ) ) {
				$this->state->active_formatting_elements->remove_node( $formatting_element );
				return;
			}

			// > If formatting element is in the stack of open elements, but the element is not in scope, then this is a parse error; return.
			if ( ! $this->state->stack_of_open_elements->has_element_in_scope( $formatting_element->node_name ) ) {
				return;
			}

			/*
			 * > Let furthest block be the topmost node in the stack of open elements that is lower in the stack
			 * > than formatting element, and is an element in the special category. There might not be one.
			 */
			$is_above_formatting_element = true;
			$furthest_block              = null;
			foreach ( $this->state->stack_of_open_elements->walk_down() as $item ) {
				if ( $is_above_formatting_element && $formatting_element->bookmark_name !== $item->bookmark_name ) {
					continue;
				}

				if ( $is_above_formatting_element ) {
					$is_above_formatting_element = false;
					continue;
				}

				if ( self::is_special( $item ) ) {
					$furthest_block = $item;
					break;
				}
			}

			/*
			 * > If there is no furthest block, then the UA must first pop all the nodes from the bottom of the
			 * > stack of open elements, from the current node up to and including formatting element, then
			 * > remove formatting element from the list of active formatting elements, and finally return.
			 */
			if ( null === $furthest_block ) {
				foreach ( $this->state->stack_of_open_elements->walk_up() as $item ) {
					$this->state->stack_of_open_elements->pop();

					if ( $formatting_element->bookmark_name === $item->bookmark_name ) {
						$this->state->active_formatting_elements->remove_node( $formatting_element );
						return;
					}
				}
			}

			$this->bail( 'Cannot extract common ancestor in adoption agency algorithm.' );
		}

		$this->bail( 'Cannot run adoption agency when looping required.' );
	}

	/**
	 * Runs the "close the cell" algorithm.
	 *
	 * > Where the steps above say to close the cell, they mean to run the following algorithm:
	 * >   1. Generate implied end tags.
	 * >   2. If the current node is not now a td element or a th element, then this is a parse error.
	 * >   3. Pop elements from the stack of open elements stack until a td element or a th element has been popped from the stack.
	 * >   4. Clear the list of active formatting elements up to the last marker.
	 * >   5. Switch the insertion mode to "in row".
	 *
	 * @see https://html.spec.whatwg.org/multipage/parsing.html#close-the-cell
	 *
	 * @since 6.7.0
	 */
	private function close_cell(): void {
		$this->generate_implied_end_tags();
		// @todo Parse error if the current node is a "td" or "th" element.
		foreach ( $this->state->stack_of_open_elements->walk_up() as $element ) {
			$this->state->stack_of_open_elements->pop();
			if ( 'TD' === $element->node_name || 'TH' === $element->node_name ) {
				break;
			}
		}
		$this->state->active_formatting_elements->clear_up_to_last_marker();
		$this->state->insertion_mode = WP_HTML_Processor_State::INSERTION_MODE_IN_ROW;
	}

	/**
	 * Inserts an HTML element on the stack of open elements.
	 *
	 * @since 6.4.0
	 *
	 * @see https://html.spec.whatwg.org/#insert-a-foreign-element
	 *
	 * @param WP_HTML_Token $token Name of bookmark pointing to element in original input HTML.
	 */
	private function insert_html_element( WP_HTML_Token $token ): void {
		$this->state->stack_of_open_elements->push( $token );
	}

	/**
	 * Inserts a foreign element on to the stack of open elements.
	 *
	 * @since 6.7.0
	 *
	 * @see https://html.spec.whatwg.org/#insert-a-foreign-element
	 *
	 * @param WP_HTML_Token $token                     Insert this token. The token's namespace and
	 *                                                 insertion point will be updated correctly.
	 * @param bool          $only_add_to_element_stack Whether to skip the "insert an element at the adjusted
	 *                                                 insertion location" algorithm when adding this element.
	 */
	private function insert_foreign_element( WP_HTML_Token $token, bool $only_add_to_element_stack ): void {
		$adjusted_current_node = $this->get_adjusted_current_node();

		$token->namespace = $adjusted_current_node ? $adjusted_current_node->namespace : 'html';

		if ( $this->is_mathml_integration_point() ) {
			$token->integration_node_type = 'math';
		} elseif ( $this->is_html_integration_point() ) {
			$token->integration_node_type = 'html';
		}

		if ( false === $only_add_to_element_stack ) {
			/*
			 * @todo Implement the "appropriate place for inserting a node" and the
			 *       "insert an element at the adjusted insertion location" algorithms.
			 *
			 * These algorithms mostly impacts DOM tree construction and not the HTML API.
			 * Here, there's no DOM node onto which the element will be appended, so the
			 * parser will skip this step.
			 *
			 * @see https://html.spec.whatwg.org/#insert-an-element-at-the-adjusted-insertion-location
			 */
		}

		$this->insert_html_element( $token );
	}

	/**
	 * Inserts a virtual element on the stack of open elements.
	 *
	 * @since 6.7.0
	 *
	 * @param string      $token_name    Name of token to create and insert into the stack of open elements.
	 * @param string|null $bookmark_name Optional. Name to give bookmark for created virtual node.
	 *                                   Defaults to auto-creating a bookmark name.
	 * @return WP_HTML_Token Newly-created virtual token.
	 */
	private function insert_virtual_node( $token_name, $bookmark_name = null ): WP_HTML_Token {
		$here = $this->bookmarks[ $this->state->current_token->bookmark_name ];
		$name = $bookmark_name ?? $this->bookmark_token();

		$this->bookmarks[ $name ] = new WP_HTML_Span( $here->start, 0 );

		$token = new WP_HTML_Token( $name, $token_name, false );
		$this->insert_html_element( $token );
		return $token;
	}

	/*
	 * HTML Specification Helpers
	 */

	/**
	 * Indicates if the current token is a MathML integration point.
	 *
	 * @since 6.7.0
	 *
	 * @see https://html.spec.whatwg.org/#mathml-text-integration-point
	 *
	 * @return bool Whether the current token is a MathML integration point.
	 */
	private function is_mathml_integration_point(): bool {
		$current_token = $this->state->current_token;
		if ( ! isset( $current_token ) ) {
			return false;
		}

		if ( 'math' !== $current_token->namespace || 'M' !== $current_token->node_name[0] ) {
			return false;
		}

		$tag_name = $current_token->node_name;

		return (
			'MI' === $tag_name ||
			'MO' === $tag_name ||
			'MN' === $tag_name ||
			'MS' === $tag_name ||
			'MTEXT' === $tag_name
		);
	}

	/**
	 * Indicates if the current token is an HTML integration point.
	 *
	 * Note that this method must be an instance method with access
	 * to the current token, since it needs to examine the attributes
	 * of the currently-matched tag, if it's in the MathML namespace.
	 * Otherwise it would be required to scan the HTML and ensure that
	 * no other accounting is overlooked.
	 *
	 * @since 6.7.0
	 *
	 * @see https://html.spec.whatwg.org/#html-integration-point
	 *
	 * @return bool Whether the current token is an HTML integration point.
	 */
	private function is_html_integration_point(): bool {
		$current_token = $this->state->current_token;
		if ( ! isset( $current_token ) ) {
			return false;
		}

		if ( 'html' === $current_token->namespace ) {
			return false;
		}

		$tag_name = $current_token->node_name;

		if ( 'svg' === $current_token->namespace ) {
			return (
				'DESC' === $tag_name ||
				'FOREIGNOBJECT' === $tag_name ||
				'TITLE' === $tag_name
			);
		}

		if ( 'math' === $current_token->namespace ) {
			if ( 'ANNOTATION-XML' !== $tag_name ) {
				return false;
			}

			$encoding = $this->get_attribute( 'encoding' );

			return (
				is_string( $encoding ) &&
				(
					0 === strcasecmp( $encoding, 'application/xhtml+xml' ) ||
					0 === strcasecmp( $encoding, 'text/html' )
				)
			);
		}

		$this->bail( 'Should not have reached end of HTML Integration Point detection: check HTML API code.' );
		// This unnecessary return prevents tools from inaccurately reporting type errors.
		return false;
	}

	/**
	 * Returns whether an element of a given name is in the HTML special category.
	 *
	 * @since 6.4.0
	 *
	 * @see https://html.spec.whatwg.org/#special
	 *
	 * @param WP_HTML_Token|string $tag_name Node to check, or only its name if in the HTML namespace.
	 * @return bool Whether the element of the given name is in the special category.
	 */
	public static function is_special( $tag_name ): bool {
		if ( is_string( $tag_name ) ) {
			$tag_name = strtoupper( $tag_name );
		} else {
			$tag_name = 'html' === $tag_name->namespace
				? strtoupper( $tag_name->node_name )
				: "{$tag_name->namespace} {$tag_name->node_name}";
		}

		return (
			'ADDRESS' === $tag_name ||
			'APPLET' === $tag_name ||
			'AREA' === $tag_name ||
			'ARTICLE' === $tag_name ||
			'ASIDE' === $tag_name ||
			'BASE' === $tag_name ||
			'BASEFONT' === $tag_name ||
			'BGSOUND' === $tag_name ||
			'BLOCKQUOTE' === $tag_name ||
			'BODY' === $tag_name ||
			'BR' === $tag_name ||
			'BUTTON' === $tag_name ||
			'CAPTION' === $tag_name ||
			'CENTER' === $tag_name ||
			'COL' === $tag_name ||
			'COLGROUP' === $tag_name ||
			'DD' === $tag_name ||
			'DETAILS' === $tag_name ||
			'DIR' === $tag_name ||
			'DIV' === $tag_name ||
			'DL' === $tag_name ||
			'DT' === $tag_name ||
			'EMBED' === $tag_name ||
			'FIELDSET' === $tag_name ||
			'FIGCAPTION' === $tag_name ||
			'FIGURE' === $tag_name ||
			'FOOTER' === $tag_name ||
			'FORM' === $tag_name ||
			'FRAME' === $tag_name ||
			'FRAMESET' === $tag_name ||
			'H1' === $tag_name ||
			'H2' === $tag_name ||
			'H3' === $tag_name ||
			'H4' === $tag_name ||
			'H5' === $tag_name ||
			'H6' === $tag_name ||
			'HEAD' === $tag_name ||
			'HEADER' === $tag_name ||
			'HGROUP' === $tag_name ||
			'HR' === $tag_name ||
			'HTML' === $tag_name ||
			'IFRAME' === $tag_name ||
			'IMG' === $tag_name ||
			'INPUT' === $tag_name ||
			'KEYGEN' === $tag_name ||
			'LI' === $tag_name ||
			'LINK' === $tag_name ||
			'LISTING' === $tag_name ||
			'MAIN' === $tag_name ||
			'MARQUEE' === $tag_name ||
			'MENU' === $tag_name ||
			'META' === $tag_name ||
			'NAV' === $tag_name ||
			'NOEMBED' === $tag_name ||
			'NOFRAMES' === $tag_name ||
			'NOSCRIPT' === $tag_name ||
			'OBJECT' === $tag_name ||
			'OL' === $tag_name ||
			'P' === $tag_name ||
			'PARAM' === $tag_name ||
			'PLAINTEXT' === $tag_name ||
			'PRE' === $tag_name ||
			'SCRIPT' === $tag_name ||
			'SEARCH' === $tag_name ||
			'SECTION' === $tag_name ||
			'SELECT' === $tag_name ||
			'SOURCE' === $tag_name ||
			'STYLE' === $tag_name ||
			'SUMMARY' === $tag_name ||
			'TABLE' === $tag_name ||
			'TBODY' === $tag_name ||
			'TD' === $tag_name ||
			'TEMPLATE' === $tag_name ||
			'TEXTAREA' === $tag_name ||
			'TFOOT' === $tag_name ||
			'TH' === $tag_name ||
			'THEAD' === $tag_name ||
			'TITLE' === $tag_name ||
			'TR' === $tag_name ||
			'TRACK' === $tag_name ||
			'UL' === $tag_name ||
			'WBR' === $tag_name ||
			'XMP' === $tag_name ||

			// MathML.
			'math MI' === $tag_name ||
			'math MO' === $tag_name ||
			'math MN' === $tag_name ||
			'math MS' === $tag_name ||
			'math MTEXT' === $tag_name ||
			'math ANNOTATION-XML' === $tag_name ||

			// SVG.
			'svg DESC' === $tag_name ||
			'svg FOREIGNOBJECT' === $tag_name ||
			'svg TITLE' === $tag_name
		);
	}

	/**
	 * Returns whether a given element is an HTML Void Element
	 *
	 * > area, base, br, col, embed, hr, img, input, link, meta, source, track, wbr
	 *
	 * @since 6.4.0
	 *
	 * @see https://html.spec.whatwg.org/#void-elements
	 *
	 * @param string $tag_name Name of HTML tag to check.
	 * @return bool Whether the given tag is an HTML Void Element.
	 */
	public static function is_void( $tag_name ): bool {
		$tag_name = strtoupper( $tag_name );

		return (
			'AREA' === $tag_name ||
			'BASE' === $tag_name ||
			'BASEFONT' === $tag_name || // Obsolete but still treated as void.
			'BGSOUND' === $tag_name || // Obsolete but still treated as void.
			'BR' === $tag_name ||
			'COL' === $tag_name ||
			'EMBED' === $tag_name ||
			'FRAME' === $tag_name ||
			'HR' === $tag_name ||
			'IMG' === $tag_name ||
			'INPUT' === $tag_name ||
			'KEYGEN' === $tag_name || // Obsolete but still treated as void.
			'LINK' === $tag_name ||
			'META' === $tag_name ||
			'PARAM' === $tag_name || // Obsolete but still treated as void.
			'SOURCE' === $tag_name ||
			'TRACK' === $tag_name ||
			'WBR' === $tag_name
		);
	}

	/**
	 * Gets an encoding from a given string.
	 *
	 * This is an algorithm defined in the WHAT-WG specification.
	 *
	 * Example:
	 *
	 *     'UTF-8' === self::get_encoding( 'utf8' );
	 *     'UTF-8' === self::get_encoding( "  \tUTF-8 " );
	 *     null    === self::get_encoding( 'UTF-7' );
	 *     null    === self::get_encoding( 'utf8; charset=' );
	 *
	 * @see https://encoding.spec.whatwg.org/#concept-encoding-get
	 *
	 * @todo As this parser only supports UTF-8, only the UTF-8
	 *       encodings are detected. Add more as desired, but the
	 *       parser will bail on non-UTF-8 encodings.
	 *
	 * @since 6.7.0
	 *
	 * @param string $label A string which may specify a known encoding.
	 * @return string|null Known encoding if matched, otherwise null.
	 */
	protected static function get_encoding( string $label ): ?string {
		/*
		 * > Remove any leading and trailing ASCII whitespace from label.
		 */
		$label = trim( $label, " \t\f\r\n" );

		/*
		 * > If label is an ASCII case-insensitive match for any of the labels listed in the
		 * > table below, then return the corresponding encoding; otherwise return failure.
		 */
		switch ( strtolower( $label ) ) {
			case 'unicode-1-1-utf-8':
			case 'unicode11utf8':
			case 'unicode20utf8':
			case 'utf-8':
			case 'utf8':
			case 'x-unicode20utf8':
				return 'UTF-8';

			default:
				return null;
		}
	}

	/*
	 * Constants that would pollute the top of the class if they were found there.
	 */

	/**
	 * Indicates that the next HTML token should be parsed and processed.
	 *
	 * @since 6.4.0
	 *
	 * @var string
	 */
	const PROCESS_NEXT_NODE = 'process-next-node';

	/**
	 * Indicates that the current HTML token should be reprocessed in the newly-selected insertion mode.
	 *
	 * @since 6.4.0
	 *
	 * @var string
	 */
	const REPROCESS_CURRENT_NODE = 'reprocess-current-node';

	/**
	 * Indicates that the current HTML token should be processed without advancing the parser.
	 *
	 * @since 6.5.0
	 *
	 * @var string
	 */
	const PROCESS_CURRENT_NODE = 'process-current-node';

	/**
	 * Indicates that the parser encountered unsupported markup and has bailed.
	 *
	 * @since 6.4.0
	 *
	 * @var string
	 */
	const ERROR_UNSUPPORTED = 'unsupported';

	/**
	 * Indicates that the parser encountered more HTML tokens than it
	 * was able to process and has bailed.
	 *
	 * @since 6.4.0
	 *
	 * @var string
	 */
	const ERROR_EXCEEDED_MAX_BOOKMARKS = 'exceeded-max-bookmarks';

	/**
	 * Unlock code that must be passed into the constructor to create this class.
	 *
	 * This class extends the WP_HTML_Tag_Processor, which has a public class
	 * constructor. Therefore, it's not possible to have a private constructor here.
	 *
	 * This unlock code is used to ensure that anyone calling the constructor is
	 * doing so with a full understanding that it's intended to be a private API.
	 *
	 * @access private
	 */
	const CONSTRUCTOR_UNLOCK_CODE = 'Use WP_HTML_Processor::create_fragment() instead of calling the class constructor directly.';
}
['dependencies'] : array();
	$block_version       = isset( $metadata['version'] ) ? $metadata['version'] : false;
	$script_version      = isset( $script_asset['version'] ) ? $script_asset['version'] : $block_version;
	$script_args         = array();
	if ( 'viewScript' === $field_name && $script_uri ) {
		$script_args['strategy'] = 'defer';
	}

	$result = wp_register_script(
		$script_handle,
		$script_uri,
		$script_dependencies,
		$script_version,
		$script_args
	);
	if ( ! $result ) {
		return false;
	}

	if ( ! empty( $metadata['textdomain'] ) && in_array( 'wp-i18n', $script_dependencies, true ) ) {
		wp_set_script_translations( $script_handle, $metadata['textdomain'] );
	}

	return $script_handle;
}

/**
 * Finds a style handle for the block metadata field. It detects when a path
 * to file was provided and registers the style under automatically
 * generated handle name. It returns unprocessed style handle otherwise.
 *
 * @since 5.5.0
 * @since 6.1.0 Added `$index` parameter.
 *
 * @param array  $metadata   Block metadata.
 * @param string $field_name Field name to pick from metadata.
 * @param int    $index      Optional. Index of the style to register when multiple items passed.
 *                           Default 0.
 * @return string|false Style handle provided directly or created through
 *                      style's registration, or false on failure.
 */
function register_block_style_handle( $metadata, $field_name, $index = 0 ) {
	if ( empty( $metadata[ $field_name ] ) ) {
		return false;
	}

	$style_handle = $metadata[ $field_name ];
	if ( is_array( $style_handle ) ) {
		if ( empty( $style_handle[ $index ] ) ) {
			return false;
		}
		$style_handle = $style_handle[ $index ];
	}

	$style_handle_name = generate_block_asset_handle( $metadata['name'], $field_name, $index );
	// If the style handle is already registered, skip re-registering.
	if ( wp_style_is( $style_handle_name, 'registered' ) ) {
		return $style_handle_name;
	}

	static $wpinc_path_norm = '';
	if ( ! $wpinc_path_norm ) {
		$wpinc_path_norm = wp_normalize_path( realpath( ABSPATH . WPINC ) );
	}

	$is_core_block = isset( $metadata['file'] ) && str_starts_with( $metadata['file'], $wpinc_path_norm );
	// Skip registering individual styles for each core block when a bundled version provided.
	if ( $is_core_block && ! wp_should_load_separate_core_block_assets() ) {
		return false;
	}

	$style_path      = remove_block_asset_path_prefix( $style_handle );
	$is_style_handle = $style_handle === $style_path;
	// Allow only passing style handles for core blocks.
	if ( $is_core_block && ! $is_style_handle ) {
		return false;
	}
	// Return the style handle unless it's the first item for every core block that requires special treatment.
	if ( $is_style_handle && ! ( $is_core_block && 0 === $index ) ) {
		return $style_handle;
	}

	// Check whether styles should have a ".min" suffix or not.
	$suffix = SCRIPT_DEBUG ? '' : '.min';
	if ( $is_core_block ) {
		$style_path = ( 'editorStyle' === $field_name ) ? "editor{$suffix}.css" : "style{$suffix}.css";
	}

	$style_path_norm = wp_normalize_path( realpath( dirname( $metadata['file'] ) . '/' . $style_path ) );
	$style_uri       = get_block_asset_url( $style_path_norm );

	$version = ! $is_core_block && isset( $metadata['version'] ) ? $metadata['version'] : false;
	$result  = wp_register_style(
		$style_handle_name,
		$style_uri,
		array(),
		$version
	);
	if ( ! $result ) {
		return false;
	}

	if ( $style_uri ) {
		wp_style_add_data( $style_handle_name, 'path', $style_path_norm );

		if ( $is_core_block ) {
			$rtl_file = str_replace( "{$suffix}.css", "-rtl{$suffix}.css", $style_path_norm );
		} else {
			$rtl_file = str_replace( '.css', '-rtl.css', $style_path_norm );
		}

		if ( is_rtl() && file_exists( $rtl_file ) ) {
			wp_style_add_data( $style_handle_name, 'rtl', 'replace' );
			wp_style_add_data( $style_handle_name, 'suffix', $suffix );
			wp_style_add_data( $style_handle_name, 'path', $rtl_file );
		}
	}

	return $style_handle_name;
}

/**
 * Gets i18n schema for block's metadata read from `block.json` file.
 *
 * @since 5.9.0
 *
 * @return object The schema for block's metadata.
 */
function get_block_metadata_i18n_schema() {
	static $i18n_block_schema;

	if ( ! isset( $i18n_block_schema ) ) {
		$i18n_block_schema = wp_json_file_decode( __DIR__ . '/block-i18n.json' );
	}

	return $i18n_block_schema;
}

/**
 * Registers a block metadata collection.
 *
 * This function allows core and third-party plugins to register their block metadata
 * collections in a centralized location. Registering collections can improve performance
 * by avoiding multiple reads from the filesystem and parsing JSON.
 *
 * @since 6.7.0
 *
 * @param string $path     The base path in which block files for the collection reside.
 * @param string $manifest The path to the manifest file for the collection.
 */
function wp_register_block_metadata_collection( $path, $manifest ) {
	WP_Block_Metadata_Registry::register_collection( $path, $manifest );
}

/**
 * Registers a block type from the metadata stored in the `block.json` file.
 *
 * @since 5.5.0
 * @since 5.7.0 Added support for `textdomain` field and i18n handling for all translatable fields.
 * @since 5.9.0 Added support for `variations` and `viewScript` fields.
 * @since 6.1.0 Added support for `render` field.
 * @since 6.3.0 Added `selectors` field.
 * @since 6.4.0 Added support for `blockHooks` field.
 * @since 6.5.0 Added support for `allowedBlocks`, `viewScriptModule`, and `viewStyle` fields.
 * @since 6.7.0 Allow PHP filename as `variations` argument.
 *
 * @param string $file_or_folder Path to the JSON file with metadata definition for
 *                               the block or path to the folder where the `block.json` file is located.
 *                               If providing the path to a JSON file, the filename must end with `block.json`.
 * @param array  $args           Optional. Array of block type arguments. Accepts any public property
 *                               of `WP_Block_Type`. See WP_Block_Type::__construct() for information
 *                               on accepted arguments. Default empty array.
 * @return WP_Block_Type|false The registered block type on success, or false on failure.
 */
function register_block_type_from_metadata( $file_or_folder, $args = array() ) {
	/*
	 * Get an array of metadata from a PHP file.
	 * This improves performance for core blocks as it's only necessary to read a single PHP file
	 * instead of reading a JSON file per-block, and then decoding from JSON to PHP.
	 * Using a static variable ensures that the metadata is only read once per request.
	 */

	$metadata_file = ( ! str_ends_with( $file_or_folder, 'block.json' ) ) ?
		trailingslashit( $file_or_folder ) . 'block.json' :
		$file_or_folder;

	$is_core_block        = str_starts_with( $file_or_folder, ABSPATH . WPINC );
	$metadata_file_exists = $is_core_block || file_exists( $metadata_file );
	$registry_metadata    = WP_Block_Metadata_Registry::get_metadata( $file_or_folder );

	if ( $registry_metadata ) {
		$metadata = $registry_metadata;
	} elseif ( $metadata_file_exists ) {
		$metadata = wp_json_file_decode( $metadata_file, array( 'associative' => true ) );
	} else {
		$metadata = array();
	}

	if ( ! is_array( $metadata ) || ( empty( $metadata['name'] ) && empty( $args['name'] ) ) ) {
		return false;
	}

	$metadata['file'] = $metadata_file_exists ? wp_normalize_path( realpath( $metadata_file ) ) : null;

	/**
	 * Filters the metadata provided for registering a block type.
	 *
	 * @since 5.7.0
	 *
	 * @param array $metadata Metadata for registering a block type.
	 */
	$metadata = apply_filters( 'block_type_metadata', $metadata );

	// Add `style` and `editor_style` for core blocks if missing.
	if ( ! empty( $metadata['name'] ) && str_starts_with( $metadata['name'], 'core/' ) ) {
		$block_name = str_replace( 'core/', '', $metadata['name'] );

		if ( ! isset( $metadata['style'] ) ) {
			$metadata['style'] = "wp-block-$block_name";
		}
		if ( current_theme_supports( 'wp-block-styles' ) && wp_should_load_separate_core_block_assets() ) {
			$metadata['style']   = (array) $metadata['style'];
			$metadata['style'][] = "wp-block-{$block_name}-theme";
		}
		if ( ! isset( $metadata['editorStyle'] ) ) {
			$metadata['editorStyle'] = "wp-block-{$block_name}-editor";
		}
	}

	$settings          = array();
	$property_mappings = array(
		'apiVersion'      => 'api_version',
		'name'            => 'name',
		'title'           => 'title',
		'category'        => 'category',
		'parent'          => 'parent',
		'ancestor'        => 'ancestor',
		'icon'            => 'icon',
		'description'     => 'description',
		'keywords'        => 'keywords',
		'attributes'      => 'attributes',
		'providesContext' => 'provides_context',
		'usesContext'     => 'uses_context',
		'selectors'       => 'selectors',
		'supports'        => 'supports',
		'styles'          => 'styles',
		'variations'      => 'variations',
		'example'         => 'example',
		'allowedBlocks'   => 'allowed_blocks',
	);
	$textdomain        = ! empty( $metadata['textdomain'] ) ? $metadata['textdomain'] : null;
	$i18n_schema       = get_block_metadata_i18n_schema();

	foreach ( $property_mappings as $key => $mapped_key ) {
		if ( isset( $metadata[ $key ] ) ) {
			$settings[ $mapped_key ] = $metadata[ $key ];
			if ( $metadata_file_exists && $textdomain && isset( $i18n_schema->$key ) ) {
				$settings[ $mapped_key ] = translate_settings_using_i18n_schema( $i18n_schema->$key, $settings[ $key ], $textdomain );
			}
		}
	}

	if ( ! empty( $metadata['render'] ) ) {
		$template_path = wp_normalize_path(
			realpath(
				dirname( $metadata['file'] ) . '/' .
				remove_block_asset_path_prefix( $metadata['render'] )
			)
		);
		if ( $template_path ) {
			/**
			 * Renders the block on the server.
			 *
			 * @since 6.1.0
			 *
			 * @param array    $attributes Block attributes.
			 * @param string   $content    Block default content.
			 * @param WP_Block $block      Block instance.
			 *
			 * @return string Returns the block content.
			 */
			$settings['render_callback'] = static function ( $attributes, $content, $block ) use ( $template_path ) {
				ob_start();
				require $template_path;
				return ob_get_clean();
			};
		}
	}

	// If `variations` is a string, it's the name of a PHP file that
	// generates the variations.
	if ( ! empty( $metadata['variations'] ) && is_string( $metadata['variations'] ) ) {
		$variations_path = wp_normalize_path(
			realpath(
				dirname( $metadata['file'] ) . '/' .
				remove_block_asset_path_prefix( $metadata['variations'] )
			)
		);
		if ( $variations_path ) {
			/**
			 * Generates the list of block variations.
			 *
			 * @since 6.7.0
			 *
			 * @return string Returns the list of block variations.
			 */
			$settings['variation_callback'] = static function () use ( $variations_path ) {
				$variations = require $variations_path;
				return $variations;
			};
			// The block instance's `variations` field is only allowed to be an array
			// (of known block variations). We unset it so that the block instance will
			// provide a getter that returns the result of the `variation_callback` instead.
			unset( $settings['variations'] );
		}
	}

	$settings = array_merge( $settings, $args );

	$script_fields = array(
		'editorScript' => 'editor_script_handles',
		'script'       => 'script_handles',
		'viewScript'   => 'view_script_handles',
	);
	foreach ( $script_fields as $metadata_field_name => $settings_field_name ) {
		if ( ! empty( $settings[ $metadata_field_name ] ) ) {
			$metadata[ $metadata_field_name ] = $settings[ $metadata_field_name ];
		}
		if ( ! empty( $metadata[ $metadata_field_name ] ) ) {
			$scripts           = $metadata[ $metadata_field_name ];
			$processed_scripts = array();
			if ( is_array( $scripts ) ) {
				for ( $index = 0; $index < count( $scripts ); $index++ ) {
					$result = register_block_script_handle(
						$metadata,
						$metadata_field_name,
						$index
					);
					if ( $result ) {
						$processed_scripts[] = $result;
					}
				}
			} else {
				$result = register_block_script_handle(
					$metadata,
					$metadata_field_name
				);
				if ( $result ) {
					$processed_scripts[] = $result;
				}
			}
			$settings[ $settings_field_name ] = $processed_scripts;
		}
	}

	$module_fields = array(
		'viewScriptModule' => 'view_script_module_ids',
	);
	foreach ( $module_fields as $metadata_field_name => $settings_field_name ) {
		if ( ! empty( $settings[ $metadata_field_name ] ) ) {
			$metadata[ $metadata_field_name ] = $settings[ $metadata_field_name ];
		}
		if ( ! empty( $metadata[ $metadata_field_name ] ) ) {
			$modules           = $metadata[ $metadata_field_name ];
			$processed_modules = array();
			if ( is_array( $modules ) ) {
				for ( $index = 0; $index < count( $modules ); $index++ ) {
					$result = register_block_script_module_id(
						$metadata,
						$metadata_field_name,
						$index
					);
					if ( $result ) {
						$processed_modules[] = $result;
					}
				}
			} else {
				$result = register_block_script_module_id(
					$metadata,
					$metadata_field_name
				);
				if ( $result ) {
					$processed_modules[] = $result;
				}
			}
			$settings[ $settings_field_name ] = $processed_modules;
		}
	}

	$style_fields = array(
		'editorStyle' => 'editor_style_handles',
		'style'       => 'style_handles',
		'viewStyle'   => 'view_style_handles',
	);
	foreach ( $style_fields as $metadata_field_name => $settings_field_name ) {
		if ( ! empty( $settings[ $metadata_field_name ] ) ) {
			$metadata[ $metadata_field_name ] = $settings[ $metadata_field_name ];
		}
		if ( ! empty( $metadata[ $metadata_field_name ] ) ) {
			$styles           = $metadata[ $metadata_field_name ];
			$processed_styles = array();
			if ( is_array( $styles ) ) {
				for ( $index = 0; $index < count( $styles ); $index++ ) {
					$result = register_block_style_handle(
						$metadata,
						$metadata_field_name,
						$index
					);
					if ( $result ) {
						$processed_styles[] = $result;
					}
				}
			} else {
				$result = register_block_style_handle(
					$metadata,
					$metadata_field_name
				);
				if ( $result ) {
					$processed_styles[] = $result;
				}
			}
			$settings[ $settings_field_name ] = $processed_styles;
		}
	}

	if ( ! empty( $metadata['blockHooks'] ) ) {
		/**
		 * Map camelCased position string (from block.json) to snake_cased block type position.
		 *
		 * @var array
		 */
		$position_mappings = array(
			'before'     => 'before',
			'after'      => 'after',
			'firstChild' => 'first_child',
			'lastChild'  => 'last_child',
		);

		$settings['block_hooks'] = array();
		foreach ( $metadata['blockHooks'] as $anchor_block_name => $position ) {
			// Avoid infinite recursion (hooking to itself).
			if ( $metadata['name'] === $anchor_block_name ) {
				_doing_it_wrong(
					__METHOD__,
					__( 'Cannot hook block to itself.' ),
					'6.4.0'
				);
				continue;
			}

			if ( ! isset( $position_mappings[ $position ] ) ) {
				continue;
			}

			$settings['block_hooks'][ $anchor_block_name ] = $position_mappings[ $position ];
		}
	}

	/**
	 * Filters the settings determined from the block type metadata.
	 *
	 * @since 5.7.0
	 *
	 * @param array $settings Array of determined settings for registering a block type.
	 * @param array $metadata Metadata provided for registering a block type.
	 */
	$settings = apply_filters( 'block_type_metadata_settings', $settings, $metadata );

	$metadata['name'] = ! empty( $settings['name'] ) ? $settings['name'] : $metadata['name'];

	return WP_Block_Type_Registry::get_instance()->register(
		$metadata['name'],
		$settings
	);
}

/**
 * Registers a block type. The recommended way is to register a block type using
 * the metadata stored in the `block.json` file.
 *
 * @since 5.0.0
 * @since 5.8.0 First parameter now accepts a path to the `block.json` file.
 *
 * @param string|WP_Block_Type $block_type Block type name including namespace, or alternatively
 *                                         a path to the JSON file with metadata definition for the block,
 *                                         or a path to the folder where the `block.json` file is located,
 *                                         or a complete WP_Block_Type instance.
 *                                         In case a WP_Block_Type is provided, the $args parameter will be ignored.
 * @param array                $args       Optional. Array of block type arguments. Accepts any public property
 *                                         of `WP_Block_Type`. See WP_Block_Type::__construct() for information
 *                                         on accepted arguments. Default empty array.
 *
 * @return WP_Block_Type|false The registered block type on success, or false on failure.
 */
function register_block_type( $block_type, $args = array() ) {
	if ( is_string( $block_type ) && file_exists( $block_type ) ) {
		return register_block_type_from_metadata( $block_type, $args );
	}

	return WP_Block_Type_Registry::get_instance()->register( $block_type, $args );
}

/**
 * Unregisters a block type.
 *
 * @since 5.0.0
 *
 * @param string|WP_Block_Type $name Block type name including namespace, or alternatively
 *                                   a complete WP_Block_Type instance.
 * @return WP_Block_Type|false The unregistered block type on success, or false on failure.
 */
function unregister_block_type( $name ) {
	return WP_Block_Type_Registry::get_instance()->unregister( $name );
}

/**
 * Determines whether a post or content string has blocks.
 *
 * This test optimizes for performance rather than strict accuracy, detecting
 * the pattern of a block but not validating its structure. For strict accuracy,
 * you should use the block parser on post content.
 *
 * @since 5.0.0
 *
 * @see parse_blocks()
 *
 * @param int|string|WP_Post|null $post Optional. Post content, post ID, or post object.
 *                                      Defaults to global $post.
 * @return bool Whether the post has blocks.
 */
function has_blocks( $post = null ) {
	if ( ! is_string( $post ) ) {
		$wp_post = get_post( $post );

		if ( ! $wp_post instanceof WP_Post ) {
			return false;
		}

		$post = $wp_post->post_content;
	}

	return str_contains( (string) $post, '<!-- wp:' );
}

/**
 * Determines whether a $post or a string contains a specific block type.
 *
 * This test optimizes for performance rather than strict accuracy, detecting
 * whether the block type exists but not validating its structure and not checking
 * synced patterns (formerly called reusable blocks). For strict accuracy,
 * you should use the block parser on post content.
 *
 * @since 5.0.0
 *
 * @see parse_blocks()
 *
 * @param string                  $block_name Full block type to look for.
 * @param int|string|WP_Post|null $post       Optional. Post content, post ID, or post object.
 *                                            Defaults to global $post.
 * @return bool Whether the post content contains the specified block.
 */
function has_block( $block_name, $post = null ) {
	if ( ! has_blocks( $post ) ) {
		return false;
	}

	if ( ! is_string( $post ) ) {
		$wp_post = get_post( $post );
		if ( $wp_post instanceof WP_Post ) {
			$post = $wp_post->post_content;
		}
	}

	/*
	 * Normalize block name to include namespace, if provided as non-namespaced.
	 * This matches behavior for WordPress 5.0.0 - 5.3.0 in matching blocks by
	 * their serialized names.
	 */
	if ( ! str_contains( $block_name, '/' ) ) {
		$block_name = 'core/' . $block_name;
	}

	// Test for existence of block by its fully qualified name.
	$has_block = str_contains( $post, '<!-- wp:' . $block_name . ' ' );

	if ( ! $has_block ) {
		/*
		 * If the given block name would serialize to a different name, test for
		 * existence by the serialized form.
		 */
		$serialized_block_name = strip_core_block_namespace( $block_name );
		if ( $serialized_block_name !== $block_name ) {
			$has_block = str_contains( $post, '<!-- wp:' . $serialized_block_name . ' ' );
		}
	}

	return $has_block;
}

/**
 * Returns an array of the names of all registered dynamic block types.
 *
 * @since 5.0.0
 *
 * @return string[] Array of dynamic block names.
 */
function get_dynamic_block_names() {
	$dynamic_block_names = array();

	$block_types = WP_Block_Type_Registry::get_instance()->get_all_registered();
	foreach ( $block_types as $block_type ) {
		if ( $block_type->is_dynamic() ) {
			$dynamic_block_names[] = $block_type->name;
		}
	}

	return $dynamic_block_names;
}

/**
 * Retrieves block types hooked into the given block, grouped by anchor block type and the relative position.
 *
 * @since 6.4.0
 *
 * @return array[] Array of block types grouped by anchor block type and the relative position.
 */
function get_hooked_blocks() {
	$block_types   = WP_Block_Type_Registry::get_instance()->get_all_registered();
	$hooked_blocks = array();
	foreach ( $block_types as $block_type ) {
		if ( ! ( $block_type instanceof WP_Block_Type ) || ! is_array( $block_type->block_hooks ) ) {
			continue;
		}
		foreach ( $block_type->block_hooks as $anchor_block_type => $relative_position ) {
			if ( ! isset( $hooked_blocks[ $anchor_block_type ] ) ) {
				$hooked_blocks[ $anchor_block_type ] = array();
			}
			if ( ! isset( $hooked_blocks[ $anchor_block_type ][ $relative_position ] ) ) {
				$hooked_blocks[ $anchor_block_type ][ $relative_position ] = array();
			}
			$hooked_blocks[ $anchor_block_type ][ $relative_position ][] = $block_type->name;
		}
	}

	return $hooked_blocks;
}

/**
 * Returns the markup for blocks hooked to the given anchor block in a specific relative position.
 *
 * @since 6.5.0
 * @access private
 *
 * @param array                           $parsed_anchor_block The anchor block, in parsed block array format.
 * @param string                          $relative_position   The relative position of the hooked blocks.
 *                                                             Can be one of 'before', 'after', 'first_child', or 'last_child'.
 * @param array                           $hooked_blocks       An array of hooked block types, grouped by anchor block and relative position.
 * @param WP_Block_Template|WP_Post|array $context             The block template, template part, or pattern that the anchor block belongs to.
 * @return string
 */
function insert_hooked_blocks( &$parsed_anchor_block, $relative_position, $hooked_blocks, $context ) {
	$anchor_block_type  = $parsed_anchor_block['blockName'];
	$hooked_block_types = isset( $hooked_blocks[ $anchor_block_type ][ $relative_position ] )
		? $hooked_blocks[ $anchor_block_type ][ $relative_position ]
		: array();

	/**
	 * Filters the list of hooked block types for a given anchor block type and relative position.
	 *
	 * @since 6.4.0
	 *
	 * @param string[]                        $hooked_block_types The list of hooked block types.
	 * @param string                          $relative_position  The relative position of the hooked blocks.
	 *                                                            Can be one of 'before', 'after', 'first_child', or 'last_child'.
	 * @param string                          $anchor_block_type  The anchor block type.
	 * @param WP_Block_Template|WP_Post|array $context            The block template, template part, `wp_navigation` post type,
	 *                                                            or pattern that the anchor block belongs to.
	 */
	$hooked_block_types = apply_filters( 'hooked_block_types', $hooked_block_types, $relative_position, $anchor_block_type, $context );

	$markup = '';
	foreach ( $hooked_block_types as $hooked_block_type ) {
		$parsed_hooked_block = array(
			'blockName'    => $hooked_block_type,
			'attrs'        => array(),
			'innerBlocks'  => array(),
			'innerContent' => array(),
		);

		/**
		 * Filters the parsed block array for a given hooked block.
		 *
		 * @since 6.5.0
		 *
		 * @param array|null                      $parsed_hooked_block The parsed block array for the given hooked block type, or null to suppress the block.
		 * @param string                          $hooked_block_type   The hooked block type name.
		 * @param string                          $relative_position   The relative position of the hooked block.
		 * @param array                           $parsed_anchor_block The anchor block, in parsed block array format.
		 * @param WP_Block_Template|WP_Post|array $context             The block template, template part, `wp_navigation` post type,
		 *                                                             or pattern that the anchor block belongs to.
		 */
		$parsed_hooked_block = apply_filters( 'hooked_block', $parsed_hooked_block, $hooked_block_type, $relative_position, $parsed_anchor_block, $context );

		/**
		 * Filters the parsed block array for a given hooked block.
		 *
		 * The dynamic portion of the hook name, `$hooked_block_type`, refers to the block type name of the specific hooked block.
		 *
		 * @since 6.5.0
		 *
		 * @param array|null                      $parsed_hooked_block The parsed block array for the given hooked block type, or null to suppress the block.
		 * @param string                          $hooked_block_type   The hooked block type name.
		 * @param string                          $relative_position   The relative position of the hooked block.
		 * @param array                           $parsed_anchor_block The anchor block, in parsed block array format.
		 * @param WP_Block_Template|WP_Post|array $context             The block template, template part, `wp_navigation` post type,
		 *                                                             or pattern that the anchor block belongs to.
		 */
		$parsed_hooked_block = apply_filters( "hooked_block_{$hooked_block_type}", $parsed_hooked_block, $hooked_block_type, $relative_position, $parsed_anchor_block, $context );

		if ( null === $parsed_hooked_block ) {
			continue;
		}

		// It's possible that the filter returned a block of a different type, so we explicitly
		// look for the original `$hooked_block_type` in the `ignoredHookedBlocks` metadata.
		if (
			! isset( $parsed_anchor_block['attrs']['metadata']['ignoredHookedBlocks'] ) ||
			! in_array( $hooked_block_type, $parsed_anchor_block['attrs']['metadata']['ignoredHookedBlocks'], true )
		) {
			$markup .= serialize_block( $parsed_hooked_block );
		}
	}

	return $markup;
}

/**
 * Adds a list of hooked block types to an anchor block's ignored hooked block types.
 *
 * This function is meant for internal use only.
 *
 * @since 6.5.0
 * @access private
 *
 * @param array                           $parsed_anchor_block The anchor block, in parsed block array format.
 * @param string                          $relative_position   The relative position of the hooked blocks.
 *                                                             Can be one of 'before', 'after', 'first_child', or 'last_child'.
 * @param array                           $hooked_blocks       An array of hooked block types, grouped by anchor block and relative position.
 * @param WP_Block_Template|WP_Post|array $context             The block template, template part, or pattern that the anchor block belongs to.
 * @return string Empty string.
 */
function set_ignored_hooked_blocks_metadata( &$parsed_anchor_block, $relative_position, $hooked_blocks, $context ) {
	$anchor_block_type  = $parsed_anchor_block['blockName'];
	$hooked_block_types = isset( $hooked_blocks[ $anchor_block_type ][ $relative_position ] )
		? $hooked_blocks[ $anchor_block_type ][ $relative_position ]
		: array();

	/** This filter is documented in wp-includes/blocks.php */
	$hooked_block_types = apply_filters( 'hooked_block_types', $hooked_block_types, $relative_position, $anchor_block_type, $context );
	if ( empty( $hooked_block_types ) ) {
		return '';
	}

	foreach ( $hooked_block_types as $index => $hooked_block_type ) {
		$parsed_hooked_block = array(
			'blockName'    => $hooked_block_type,
			'attrs'        => array(),
			'innerBlocks'  => array(),
			'innerContent' => array(),
		);

		/** This filter is documented in wp-includes/blocks.php */
		$parsed_hooked_block = apply_filters( 'hooked_block', $parsed_hooked_block, $hooked_block_type, $relative_position, $parsed_anchor_block, $context );

		/** This filter is documented in wp-includes/blocks.php */
		$parsed_hooked_block = apply_filters( "hooked_block_{$hooked_block_type}", $parsed_hooked_block, $hooked_block_type, $relative_position, $parsed_anchor_block, $context );

		if ( null === $parsed_hooked_block ) {
			unset( $hooked_block_types[ $index ] );
		}
	}

	$previously_ignored_hooked_blocks = isset( $parsed_anchor_block['attrs']['metadata']['ignoredHookedBlocks'] )
		? $parsed_anchor_block['attrs']['metadata']['ignoredHookedBlocks']
		: array();

	$parsed_anchor_block['attrs']['metadata']['ignoredHookedBlocks'] = array_unique(
		array_merge(
			$previously_ignored_hooked_blocks,
			$hooked_block_types
		)
	);

	// Markup for the hooked blocks has already been created (in `insert_hooked_blocks`).
	return '';
}

/**
 * Runs the hooked blocks algorithm on the given content.
 *
 * @since 6.6.0
 * @since 6.7.0 Injects the `theme` attribute into Template Part blocks, even if no hooked blocks are registered.
 * @access private
 *
 * @param string                          $content  Serialized content.
 * @param WP_Block_Template|WP_Post|array $context  A block template, template part, `wp_navigation` post object,
 *                                                  or pattern that the blocks belong to.
 * @param callable                        $callback A function that will be called for each block to generate
 *                                                  the markup for a given list of blocks that are hooked to it.
 *                                                  Default: 'insert_hooked_blocks'.
 * @return string The serialized markup.
 */
function apply_block_hooks_to_content( $content, $context, $callback = 'insert_hooked_blocks' ) {
	$hooked_blocks = get_hooked_blocks();

	$before_block_visitor = '_inject_theme_attribute_in_template_part_block';
	$after_block_visitor  = null;
	if ( ! empty( $hooked_blocks ) || has_filter( 'hooked_block_types' ) ) {
		$before_block_visitor = make_before_block_visitor( $hooked_blocks, $context, $callback );
		$after_block_visitor  = make_after_block_visitor( $hooked_blocks, $context, $callback );
	}

	$block_allows_multiple_instances = array();
	/*
	 * Remove hooked blocks from `$hooked_block_types` if they have `multiple` set to false and
	 * are already present in `$content`.
	 */
	foreach ( $hooked_blocks as $anchor_block_type => $relative_positions ) {
		foreach ( $relative_positions as $relative_position => $hooked_block_types ) {
			foreach ( $hooked_block_types as $index => $hooked_block_type ) {
				$hooked_block_type_definition =
					WP_Block_Type_Registry::get_instance()->get_registered( $hooked_block_type );

				$block_allows_multiple_instances[ $hooked_block_type ] =
					block_has_support( $hooked_block_type_definition, 'multiple', true );

				if (
					! $block_allows_multiple_instances[ $hooked_block_type ] &&
					has_block( $hooked_block_type, $content )
				) {
					unset( $hooked_blocks[ $anchor_block_type ][ $relative_position ][ $index ] );
				}
			}
			if ( empty( $hooked_blocks[ $anchor_block_type ][ $relative_position ] ) ) {
				unset( $hooked_blocks[ $anchor_block_type ][ $relative_position ] );
			}
		}
		if ( empty( $hooked_blocks[ $anchor_block_type ] ) ) {
			unset( $hooked_blocks[ $anchor_block_type ] );
		}
	}

	/*
	 * We also need to cover the case where the hooked block is not present in
	 * `$content` at first and we're allowed to insert it once -- but not again.
	 */
	$suppress_single_instance_blocks = static function ( $hooked_block_types ) use ( &$block_allows_multiple_instances, $content ) {
		static $single_instance_blocks_present_in_content = array();
		foreach ( $hooked_block_types as $index => $hooked_block_type ) {
			if ( ! isset( $block_allows_multiple_instances[ $hooked_block_type ] ) ) {
				$hooked_block_type_definition =
					WP_Block_Type_Registry::get_instance()->get_registered( $hooked_block_type );

				$block_allows_multiple_instances[ $hooked_block_type ] =
					block_has_support( $hooked_block_type_definition, 'multiple', true );
			}

			if ( $block_allows_multiple_instances[ $hooked_block_type ] ) {
				continue;
			}

			// The block doesn't allow multiple instances, so we need to check if it's already present.
			if (
				in_array( $hooked_block_type, $single_instance_blocks_present_in_content, true ) ||
				has_block( $hooked_block_type, $content )
			) {
				unset( $hooked_block_types[ $index ] );
			} else {
				// We can insert the block once, but need to remember not to insert it again.
				$single_instance_blocks_present_in_content[] = $hooked_block_type;
			}
		}
		return $hooked_block_types;
	};
	add_filter( 'hooked_block_types', $suppress_single_instance_blocks, PHP_INT_MAX );
	$content = traverse_and_serialize_blocks(
		parse_blocks( $content ),
		$before_block_visitor,
		$after_block_visitor
	);
	remove_filter( 'hooked_block_types', $suppress_single_instance_blocks, PHP_INT_MAX );

	return $content;
}

/**
 * Accepts the serialized markup of a block and its inner blocks, and returns serialized markup of the inner blocks.
 *
 * @since 6.6.0
 * @access private
 *
 * @param string $serialized_block The serialized markup of a block and its inner blocks.
 * @return string The serialized markup of the inner blocks.
 */
function remove_serialized_parent_block( $serialized_block ) {
	$start = strpos( $serialized_block, '-->' ) + strlen( '-->' );
	$end   = strrpos( $serialized_block, '<!--' );
	return substr( $serialized_block, $start, $end - $start );
}

/**
 * Accepts the serialized markup of a block and its inner blocks, and returns serialized markup of the wrapper block.
 *
 * @since 6.7.0
 * @access private
 *
 * @see remove_serialized_parent_block()
 *
 * @param string $serialized_block The serialized markup of a block and its inner blocks.
 * @return string The serialized markup of the wrapper block.
 */
function extract_serialized_parent_block( $serialized_block ) {
	$start = strpos( $serialized_block, '-->' ) + strlen( '-->' );
	$end   = strrpos( $serialized_block, '<!--' );
	return substr( $serialized_block, 0, $start ) . substr( $serialized_block, $end );
}

/**
 * Updates the wp_postmeta with the list of ignored hooked blocks where the inner blocks are stored as post content.
 * Currently only supports `wp_navigation` post types.
 *
 * @since 6.6.0
 * @access private
 *
 * @param stdClass $post Post object.
 * @return stdClass The updated post object.
 */
function update_ignored_hooked_blocks_postmeta( $post ) {
	/*
	 * In this scenario the user has likely tried to create a navigation via the REST API.
	 * In which case we won't have a post ID to work with and store meta against.
	 */
	if ( empty( $post->ID ) ) {
		return $post;
	}

	/*
	 * Skip meta generation when consumers intentionally update specific Navigation fields
	 * and omit the content update.
	 */
	if ( ! isset( $post->post_content ) ) {
		return $post;
	}

	/*
	 * Skip meta generation when the post content is not a navigation block.
	 */
	if ( ! isset( $post->post_type ) || 'wp_navigation' !== $post->post_type ) {
		return $post;
	}

	$attributes = array();

	$ignored_hooked_blocks = get_post_meta( $post->ID, '_wp_ignored_hooked_blocks', true );
	if ( ! empty( $ignored_hooked_blocks ) ) {
		$ignored_hooked_blocks  = json_decode( $ignored_hooked_blocks, true );
		$attributes['metadata'] = array(
			'ignoredHookedBlocks' => $ignored_hooked_blocks,
		);
	}

	$markup = get_comment_delimited_block_content(
		'core/navigation',
		$attributes,
		$post->post_content
	);

	$existing_post = get_post( $post->ID );
	// Merge the existing post object with the updated post object to pass to the block hooks algorithm for context.
	$context          = (object) array_merge( (array) $existing_post, (array) $post );
	$serialized_block = apply_block_hooks_to_content( $markup, $context, 'set_ignored_hooked_blocks_metadata' );
	$root_block       = parse_blocks( $serialized_block )[0];

	$ignored_hooked_blocks = isset( $root_block['attrs']['metadata']['ignoredHookedBlocks'] )
		? $root_block['attrs']['metadata']['ignoredHookedBlocks']
		: array();

	if ( ! empty( $ignored_hooked_blocks ) ) {
		$existing_ignored_hooked_blocks = get_post_meta( $post->ID, '_wp_ignored_hooked_blocks', true );
		if ( ! empty( $existing_ignored_hooked_blocks ) ) {
			$existing_ignored_hooked_blocks = json_decode( $existing_ignored_hooked_blocks, true );
			$ignored_hooked_blocks          = array_unique( array_merge( $ignored_hooked_blocks, $existing_ignored_hooked_blocks ) );
		}

		if ( ! isset( $post->meta_input ) ) {
			$post->meta_input = array();
		}
		$post->meta_input['_wp_ignored_hooked_blocks'] = json_encode( $ignored_hooked_blocks );
	}

	$post->post_content = remove_serialized_parent_block( $serialized_block );
	return $post;
}

/**
 * Returns the markup for blocks hooked to the given anchor block in a specific relative position and then
 * adds a list of hooked block types to an anchor block's ignored hooked block types.
 *
 * This function is meant for internal use only.
 *
 * @since 6.6.0
 * @access private
 *
 * @param array                           $parsed_anchor_block The anchor block, in parsed block array format.
 * @param string                          $relative_position   The relative position of the hooked blocks.
 *                                                             Can be one of 'before', 'after', 'first_child', or 'last_child'.
 * @param array                           $hooked_blocks       An array of hooked block types, grouped by anchor block and relative position.
 * @param WP_Block_Template|WP_Post|array $context             The block template, template part, or pattern that the anchor block belongs to.
 * @return string
 */
function insert_hooked_blocks_and_set_ignored_hooked_blocks_metadata( &$parsed_anchor_block, $relative_position, $hooked_blocks, $context ) {
	$markup  = insert_hooked_blocks( $parsed_anchor_block, $relative_position, $hooked_blocks, $context );
	$markup .= set_ignored_hooked_blocks_metadata( $parsed_anchor_block, $relative_position, $hooked_blocks, $context );

	return $markup;
}

/**
 * Hooks into the REST API response for the core/navigation block and adds the first and last inner blocks.
 *
 * @since 6.6.0
 *
 * @param WP_REST_Response $response The response object.
 * @param WP_Post          $post     Post object.
 * @return WP_REST_Response The response object.
 */
function insert_hooked_blocks_into_rest_response( $response, $post ) {
	if ( ! isset( $response->data['content']['raw'] ) || ! isset( $response->data['content']['rendered'] ) ) {
		return $response;
	}

	$attributes            = array();
	$ignored_hooked_blocks = get_post_meta( $post->ID, '_wp_ignored_hooked_blocks', true );
	if ( ! empty( $ignored_hooked_blocks ) ) {
		$ignored_hooked_blocks  = json_decode( $ignored_hooked_blocks, true );
		$attributes['metadata'] = array(
			'ignoredHookedBlocks' => $ignored_hooked_blocks,
		);
	}
	$content = get_comment_delimited_block_content(
		'core/navigation',
		$attributes,
		$response->data['content']['raw']
	);

	$content = apply_block_hooks_to_content( $content, $post );

	// Remove mock Navigation block wrapper.
	$content = remove_serialized_parent_block( $content );

	$response->data['content']['raw'] = $content;

	/** This filter is documented in wp-includes/post-template.php */
	$response->data['content']['rendered'] = apply_filters( 'the_content', $content );

	return $response;
}

/**
 * Returns a function that injects the theme attribute into, and hooked blocks before, a given block.
 *
 * The returned function can be used as `$pre_callback` argument to `traverse_and_serialize_block(s)`,
 * where it will inject the `theme` attribute into all Template Part blocks, and prepend the markup for
 * any blocks hooked `before` the given block and as its parent's `first_child`, respectively.
 *
 * This function is meant for internal use only.
 *
 * @since 6.4.0
 * @since 6.5.0 Added $callback argument.
 * @access private
 *
 * @param array                           $hooked_blocks An array of blocks hooked to another given block.
 * @param WP_Block_Template|WP_Post|array $context       A block template, template part, `wp_navigation` post object,
 *                                                       or pattern that the blocks belong to.
 * @param callable                        $callback      A function that will be called for each block to generate
 *                                                       the markup for a given list of blocks that are hooked to it.
 *                                                       Default: 'insert_hooked_blocks'.
 * @return callable A function that returns the serialized markup for the given block,
 *                  including the markup for any hooked blocks before it.
 */
function make_before_block_visitor( $hooked_blocks, $context, $callback = 'insert_hooked_blocks' ) {
	/**
	 * Injects hooked blocks before the given block, injects the `theme` attribute into Template Part blocks, and returns the serialized markup.
	 *
	 * If the current block is a Template Part block, inject the `theme` attribute.
	 * Furthermore, prepend the markup for any blocks hooked `before` the given block and as its parent's
	 * `first_child`, respectively, to the serialized markup for the given block.
	 *
	 * @param array $block        The block to inject the theme attribute into, and hooked blocks before. Passed by reference.
	 * @param array $parent_block The parent block of the given block. Passed by reference. Default null.
	 * @param array $prev         The previous sibling block of the given block. Default null.
	 * @return string The serialized markup for the given block, with the markup for any hooked blocks prepended to it.
	 */
	return function ( &$block, &$parent_block = null, $prev = null ) use ( $hooked_blocks, $context, $callback ) {
		_inject_theme_attribute_in_template_part_block( $block );

		$markup = '';

		if ( $parent_block && ! $prev ) {
			// Candidate for first-child insertion.
			$markup .= call_user_func_array(
				$callback,
				array( &$parent_block, 'first_child', $hooked_blocks, $context )
			);
		}

		$markup .= call_user_func_array(
			$callback,
			array( &$block, 'before', $hooked_blocks, $context )
		);

		return $markup;
	};
}

/**
 * Returns a function that injects the hooked blocks after a given block.
 *
 * The returned function can be used as `$post_callback` argument to `traverse_and_serialize_block(s)`,
 * where it will append the markup for any blocks hooked `after` the given block and as its parent's
 * `last_child`, respectively.
 *
 * This function is meant for internal use only.
 *
 * @since 6.4.0
 * @since 6.5.0 Added $callback argument.
 * @access private
 *
 * @param array                           $hooked_blocks An array of blocks hooked to another block.
 * @param WP_Block_Template|WP_Post|array $context       A block template, template part, `wp_navigation` post object,
 *                                                       or pattern that the blocks belong to.
 * @param callable                        $callback      A function that will be called for each block to generate
 *                                                       the markup for a given list of blocks that are hooked to it.
 *                                                       Default: 'insert_hooked_blocks'.
 * @return callable A function that returns the serialized markup for the given block,
 *                  including the markup for any hooked blocks after it.
 */
function make_after_block_visitor( $hooked_blocks, $context, $callback = 'insert_hooked_blocks' ) {
	/**
	 * Injects hooked blocks after the given block, and returns the serialized markup.
	 *
	 * Append the markup for any blocks hooked `after` the given block and as its parent's
	 * `last_child`, respectively, to the serialized markup for the given block.
	 *
	 * @param array $block        The block to inject the hooked blocks after. Passed by reference.
	 * @param array $parent_block The parent block of the given block. Passed by reference. Default null.
	 * @param array $next         The next sibling block of the given block. Default null.
	 * @return string The serialized markup for the given block, with the markup for any hooked blocks appended to it.
	 */
	return function ( &$block, &$parent_block = null, $next = null ) use ( $hooked_blocks, $context, $callback ) {
		$markup = call_user_func_array(
			$callback,
			array( &$block, 'after', $hooked_blocks, $context )
		);

		if ( $parent_block && ! $next ) {
			// Candidate for last-child insertion.
			$markup .= call_user_func_array(
				$callback,
				array( &$parent_block, 'last_child', $hooked_blocks, $context )
			);
		}

		return $markup;
	};
}

/**
 * Given an array of attributes, returns a string in the serialized attributes
 * format prepared for post content.
 *
 * The serialized result is a JSON-encoded string, with unicode escape sequence
 * substitution for characters which might otherwise interfere with embedding
 * the result in an HTML comment.
 *
 * This function must produce output that remains in sync with the output of
 * the serializeAttributes JavaScript function in the block editor in order
 * to ensure consistent operation between PHP and JavaScript.
 *
 * @since 5.3.1
 *
 * @param array $block_attributes Attributes object.
 * @return string Serialized attributes.
 */
function serialize_block_attributes( $block_attributes ) {
	$encoded_attributes = wp_json_encode( $block_attributes, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE );
	$encoded_attributes = preg_replace( '/--/', '\\u002d\\u002d', $encoded_attributes );
	$encoded_attributes = preg_replace( '/</', '\\u003c', $encoded_attributes );
	$encoded_attributes = preg_replace( '/>/', '\\u003e', $encoded_attributes );
	$encoded_attributes = preg_replace( '/&/', '\\u0026', $encoded_attributes );
	// Regex: /\\"/
	$encoded_attributes = preg_replace( '/\\\\"/', '\\u0022', $encoded_attributes );

	return $encoded_attributes;
}

/**
 * Returns the block name to use for serialization. This will remove the default
 * "core/" namespace from a block name.
 *
 * @since 5.3.1
 *
 * @param string|null $block_name Optional. Original block name. Null if the block name is unknown,
 *                                e.g. Classic blocks have their name set to null. Default null.
 * @return string Block name to use for serialization.
 */
function strip_core_block_namespace( $block_name = null ) {
	if ( is_string( $block_name ) && str_starts_with( $block_name, 'core/' ) ) {
		return substr( $block_name, 5 );
	}

	return $block_name;
}

/**
 * Returns the content of a block, including comment delimiters.
 *
 * @since 5.3.1
 *
 * @param string|null $block_name       Block name. Null if the block name is unknown,
 *                                      e.g. Classic blocks have their name set to null.
 * @param array       $block_attributes Block attributes.
 * @param string      $block_content    Block save content.
 * @return string Comment-delimited block content.
 */
function get_comment_delimited_block_content( $block_name, $block_attributes, $block_content ) {
	if ( is_null( $block_name ) ) {
		return $block_content;
	}

	$serialized_block_name = strip_core_block_namespace( $block_name );
	$serialized_attributes = empty( $block_attributes ) ? '' : serialize_block_attributes( $block_attributes ) . ' ';

	if ( empty( $block_content ) ) {
		return sprintf( '<!-- wp:%s %s/-->', $serialized_block_name, $serialized_attributes );
	}

	return sprintf(
		'<!-- wp:%s %s-->%s<!-- /wp:%s -->',
		$serialized_block_name,
		$serialized_attributes,
		$block_content,
		$serialized_block_name
	);
}

/**
 * Returns the content of a block, including comment delimiters, serializing all
 * attributes from the given parsed block.
 *
 * This should be used when preparing a block to be saved to post content.
 * Prefer `render_block` when preparing a block for display. Unlike
 * `render_block`, this does not evaluate a block's `render_callback`, and will
 * instead preserve the markup as parsed.
 *
 * @since 5.3.1
 *
 * @param array $block {
 *     An associative array of a single parsed block object. See WP_Block_Parser_Block.
 *
 *     @type string   $blockName    Name of block.
 *     @type array    $attrs        Attributes from block comment delimiters.
 *     @type array[]  $innerBlocks  List of inner blocks. An array of arrays that
 *                                  have the same structure as this one.
 *     @type string   $innerHTML    HTML from inside block comment delimiters.
 *     @type array    $innerContent List of string fragments and null markers where
 *                                  inner blocks were found.
 * }
 * @return string String of rendered HTML.
 */
function serialize_block( $block ) {
	$block_content = '';

	$index = 0;
	foreach ( $block['innerContent'] as $chunk ) {
		$block_content .= is_string( $chunk ) ? $chunk : serialize_block( $block['innerBlocks'][ $index++ ] );
	}

	if ( ! is_array( $block['attrs'] ) ) {
		$block['attrs'] = array();
	}

	return get_comment_delimited_block_content(
		$block['blockName'],
		$block['attrs'],
		$block_content
	);
}

/**
 * Returns a joined string of the aggregate serialization of the given
 * parsed blocks.
 *
 * @since 5.3.1
 *
 * @param array[] $blocks {
 *     Array of block structures.
 *
 *     @type array ...$0 {
 *         An associative array of a single parsed block object. See WP_Block_Parser_Block.
 *
 *         @type string   $blockName    Name of block.
 *         @type array    $attrs        Attributes from block comment delimiters.
 *         @type array[]  $innerBlocks  List of inner blocks. An array of arrays that
 *                                      have the same structure as this one.
 *         @type string   $innerHTML    HTML from inside block comment delimiters.
 *         @type array    $innerContent List of string fragments and null markers where
 *                                      inner blocks were found.
 *     }
 * }
 * @return string String of rendered HTML.
 */
function serialize_blocks( $blocks ) {
	return implode( '', array_map( 'serialize_block', $blocks ) );
}

/**
 * Traverses a parsed block tree and applies callbacks before and after serializing it.
 *
 * Recursively traverses the block and its inner blocks and applies the two callbacks provided as
 * arguments, the first one before serializing the block, and the second one after serializing it.
 * If either callback returns a string value, it will be prepended and appended to the serialized
 * block markup, respectively.
 *
 * The callbacks will receive a reference to the current block as their first argument, so that they
 * can also modify it, and the current block's parent block as second argument. Finally, the
 * `$pre_callback` receives the previous block, whereas the `$post_callback` receives
 * the next block as third argument.
 *
 * Serialized blocks are returned including comment delimiters, and with all attributes serialized.
 *
 * This function should be used when there is a need to modify the saved block, or to inject markup
 * into the return value. Prefer `serialize_block` when preparing a block to be saved to post content.
 *
 * This function is meant for internal use only.
 *
 * @since 6.4.0
 * @access private
 *
 * @see serialize_block()
 *
 * @param array    $block         An associative array of a single parsed block object. See WP_Block_Parser_Block.
 * @param callable $pre_callback  Callback to run on each block in the tree before it is traversed and serialized.
 *                                It is called with the following arguments: &$block, $parent_block, $previous_block.
 *                                Its string return value will be prepended to the serialized block markup.
 * @param callable $post_callback Callback to run on each block in the tree after it is traversed and serialized.
 *                                It is called with the following arguments: &$block, $parent_block, $next_block.
 *                                Its string return value will be appended to the serialized block markup.
 * @return string Serialized block markup.
 */
function traverse_and_serialize_block( $block, $pre_callback = null, $post_callback = null ) {
	$block_content = '';
	$block_index   = 0;

	foreach ( $block['innerContent'] as $chunk ) {
		if ( is_string( $chunk ) ) {
			$block_content .= $chunk;
		} else {
			$inner_block = $block['innerBlocks'][ $block_index ];

			if ( is_callable( $pre_callback ) ) {
				$prev = 0 === $block_index
					? null
					: $block['innerBlocks'][ $block_index - 1 ];

				$block_content .= call_user_func_array(
					$pre_callback,
					array( &$inner_block, &$block, $prev )
				);
			}

			if ( is_callable( $post_callback ) ) {
				$next = count( $block['innerBlocks'] ) - 1 === $block_index
					? null
					: $block['innerBlocks'][ $block_index + 1 ];

				$post_markup = call_user_func_array(
					$post_callback,
					array( &$inner_block, &$block, $next )
				);
			}

			$block_content .= traverse_and_serialize_block( $inner_block, $pre_callback, $post_callback );
			$block_content .= isset( $post_markup ) ? $post_markup : '';

			++$block_index;
		}
	}

	if ( ! is_array( $block['attrs'] ) ) {
		$block['attrs'] = array();
	}

	return get_comment_delimited_block_content(
		$block['blockName'],
		$block['attrs'],
		$block_content
	);
}

/**
 * Replaces patterns in a block tree with their content.
 *
 * @since 6.6.0
 *
 * @param array $blocks An array blocks.
 *
 * @return array An array of blocks with patterns replaced by their content.
 */
function resolve_pattern_blocks( $blocks ) {
	static $inner_content;
	// Keep track of seen references to avoid infinite loops.
	static $seen_refs = array();
	$i                = 0;
	while ( $i < count( $blocks ) ) {
		if ( 'core/pattern' === $blocks[ $i ]['blockName'] ) {
			$attrs = $blocks[ $i ]['attrs'];

			if ( empty( $attrs['slug'] ) ) {
				++$i;
				continue;
			}

			$slug = $attrs['slug'];

			if ( isset( $seen_refs[ $slug ] ) ) {
				// Skip recursive patterns.
				array_splice( $blocks, $i, 1 );
				continue;
			}

			$registry = WP_Block_Patterns_Registry::get_instance();
			$pattern  = $registry->get_registered( $slug );

			// Skip unknown patterns.
			if ( ! $pattern ) {
				++$i;
				continue;
			}

			$blocks_to_insert   = parse_blocks( $pattern['content'] );
			$seen_refs[ $slug ] = true;
			$prev_inner_content = $inner_content;
			$inner_content      = null;
			$blocks_to_insert   = resolve_pattern_blocks( $blocks_to_insert );
			$inner_content      = $prev_inner_content;
			unset( $seen_refs[ $slug ] );
			array_splice( $blocks, $i, 1, $blocks_to_insert );

			// If we have inner content, we need to insert nulls in the
			// inner content array, otherwise serialize_blocks will skip
			// blocks.
			if ( $inner_content ) {
				$null_indices  = array_keys( $inner_content, null, true );
				$content_index = $null_indices[ $i ];
				$nulls         = array_fill( 0, count( $blocks_to_insert ), null );
				array_splice( $inner_content, $content_index, 1, $nulls );
			}

			// Skip inserted blocks.
			$i += count( $blocks_to_insert );
		} else {
			if ( ! empty( $blocks[ $i ]['innerBlocks'] ) ) {
				$prev_inner_content           = $inner_content;
				$inner_content                = $blocks[ $i ]['innerContent'];
				$blocks[ $i ]['innerBlocks']  = resolve_pattern_blocks(
					$blocks[ $i ]['innerBlocks']
				);
				$blocks[ $i ]['innerContent'] = $inner_content;
				$inner_content                = $prev_inner_content;
			}
			++$i;
		}
	}
	return $blocks;
}

/**
 * Given an array of parsed block trees, applies callbacks before and after serializing them and
 * returns their concatenated output.
 *
 * Recursively traverses the blocks and their inner blocks and applies the two callbacks provided as
 * arguments, the first one before serializing a block, and the second one after serializing.
 * If either callback returns a string value, it will be prepended and appended to the serialized
 * block markup, respectively.
 *
 * The callbacks will receive a reference to the current block as their first argument, so that they
 * can also modify it, and the current block's parent block as second argument. Finally, the
 * `$pre_callback` receives the previous block, whereas the `$post_callback` receives
 * the next block as third argument.
 *
 * Serialized blocks are returned including comment delimiters, and with all attributes serialized.
 *
 * This function should be used when there is a need to modify the saved blocks, or to inject markup
 * into the return value. Prefer `serialize_blocks` when preparing blocks to be saved to post content.
 *
 * This function is meant for internal use only.
 *
 * @since 6.4.0
 * @access private
 *
 * @see serialize_blocks()
 *
 * @param array[]  $blocks        An array of parsed blocks. See WP_Block_Parser_Block.
 * @param callable $pre_callback  Callback to run on each block in the tree before it is traversed and serialized.
 *                                It is called with the following arguments: &$block, $parent_block, $previous_block.
 *                                Its string return value will be prepended to the serialized block markup.
 * @param callable $post_callback Callback to run on each block in the tree after it is traversed and serialized.
 *                                It is called with the following arguments: &$block, $parent_block, $next_block.
 *                                Its string return value will be appended to the serialized block markup.
 * @return string Serialized block markup.
 */
function traverse_and_serialize_blocks( $blocks, $pre_callback = null, $post_callback = null ) {
	$result       = '';
	$parent_block = null; // At the top level, there is no parent block to pass to the callbacks; yet the callbacks expect a reference.

	$pre_callback_is_callable  = is_callable( $pre_callback );
	$post_callback_is_callable = is_callable( $post_callback );

	foreach ( $blocks as $index => $block ) {
		if ( $pre_callback_is_callable ) {
			$prev = 0 === $index
				? null
				: $blocks[ $index - 1 ];

			$result .= call_user_func_array(
				$pre_callback,
				array( &$block, &$parent_block, $prev )
			);
		}

		if ( $post_callback_is_callable ) {
			$next = count( $blocks ) - 1 === $index
				? null
				: $blocks[ $index + 1 ];

			$post_markup = call_user_func_array(
				$post_callback,
				array( &$block, &$parent_block, $next )
			);
		}

		$result .= traverse_and_serialize_block( $block, $pre_callback, $post_callback );
		$result .= isset( $post_markup ) ? $post_markup : '';
	}

	return $result;
}

/**
 * Filters and sanitizes block content to remove non-allowable HTML
 * from parsed block attribute values.
 *
 * @since 5.3.1
 *
 * @param string         $text              Text that may contain block content.
 * @param array[]|string $allowed_html      Optional. An array of allowed HTML elements and attributes,
 *                                          or a context name such as 'post'. See wp_kses_allowed_html()
 *                                          for the list of accepted context names. Default 'post'.
 * @param string[]       $allowed_protocols Optional. Array of allowed URL protocols.
 *                                          Defaults to the result of wp_allowed_protocols().
 * @return string The filtered and sanitized content result.
 */
function filter_block_content( $text, $allowed_html = 'post', $allowed_protocols = array() ) {
	$result = '';

	if ( str_contains( $text, '<!--' ) && str_contains( $text, '--->' ) ) {
		$text = preg_replace_callback( '%<!--(.*?)--->%', '_filter_block_content_callback', $text );
	}

	$blocks = parse_blocks( $text );
	foreach ( $blocks as $block ) {
		$block   = filter_block_kses( $block, $allowed_html, $allowed_protocols );
		$result .= serialize_block( $block );
	}

	return $result;
}

/**
 * Callback used for regular expression replacement in filter_block_content().
 *
 * @since 6.2.1
 * @access private
 *
 * @param array $matches Array of preg_replace_callback matches.
 * @return string Replacement string.
 */
function _filter_block_content_callback( $matches ) {
	return '<!--' . rtrim( $matches[1], '-' ) . '-->';
}

/**
 * Filters and sanitizes a parsed block to remove non-allowable HTML
 * from block attribute values.
 *
 * @since 5.3.1
 *
 * @param WP_Block_Parser_Block $block             The parsed block object.
 * @param array[]|string        $allowed_html      An array of allowed HTML elements and attributes,
 *                                                 or a context name such as 'post'. See wp_kses_allowed_html()
 *                                                 for the list of accepted context names.
 * @param string[]              $allowed_protocols Optional. Array of allowed URL protocols.
 *                                                 Defaults to the result of wp_allowed_protocols().
 * @return array The filtered and sanitized block object result.
 */
function filter_block_kses( $block, $allowed_html, $allowed_protocols = array() ) {
	$block['attrs'] = filter_block_kses_value( $block['attrs'], $allowed_html, $allowed_protocols, $block );

	if ( is_array( $block['innerBlocks'] ) ) {
		foreach ( $block['innerBlocks'] as $i => $inner_block ) {
			$block['innerBlocks'][ $i ] = filter_block_kses( $inner_block, $allowed_html, $allowed_protocols );
		}
	}

	return $block;
}

/**
 * Filters and sanitizes a parsed block attribute value to remove
 * non-allowable HTML.
 *
 * @since 5.3.1
 * @since 6.5.5 Added the `$block_context` parameter.
 *
 * @param string[]|string $value             The attribute value to filter.
 * @param array[]|string  $allowed_html      An array of allowed HTML elements and attributes,
 *                                           or a context name such as 'post'. See wp_kses_allowed_html()
 *                                           for the list of accepted context names.
 * @param string[]        $allowed_protocols Optional. Array of allowed URL protocols.
 *                                           Defaults to the result of wp_allowed_protocols().
 * @param array           $block_context     Optional. The block the attribute belongs to, in parsed block array format.
 * @return string[]|string The filtered and sanitized result.
 */
function filter_block_kses_value( $value, $allowed_html, $allowed_protocols = array(), $block_context = null ) {
	if ( is_array( $value ) ) {
		foreach ( $value as $key => $inner_value ) {
			$filtered_key   = filter_block_kses_value( $key, $allowed_html, $allowed_protocols, $block_context );
			$filtered_value = filter_block_kses_value( $inner_value, $allowed_html, $allowed_protocols, $block_context );

			if ( isset( $block_context['blockName'] ) && 'core/template-part' === $block_context['blockName'] ) {
				$filtered_value = filter_block_core_template_part_attributes( $filtered_value, $filtered_key, $allowed_html );
			}
			if ( $filtered_key !== $key ) {
				unset( $value[ $key ] );
			}

			$value[ $filtered_key ] = $filtered_value;
		}
	} elseif ( is_string( $value ) ) {
		return wp_kses( $value, $allowed_html, $allowed_protocols );
	}

	return $value;
}

/**
 * Sanitizes the value of the Template Part block's `tagName` attribute.
 *
 * @since 6.5.5
 *
 * @param string         $attribute_value The attribute value to filter.
 * @param string         $attribute_name  The attribute name.
 * @param array[]|string $allowed_html    An array of allowed HTML elements and attributes,
 *                                        or a context name such as 'post'. See wp_kses_allowed_html()
 *                                        for the list of accepted context names.
 * @return string The sanitized attribute value.
 */
function filter_block_core_template_part_attributes( $attribute_value, $attribute_name, $allowed_html ) {
	if ( empty( $attribute_value ) || 'tagName' !== $attribute_name ) {
		return $attribute_value;
	}
	if ( ! is_array( $allowed_html ) ) {
		$allowed_html = wp_kses_allowed_html( $allowed_html );
	}
	return isset( $allowed_html[ $attribute_value ] ) ? $attribute_value : '';
}

/**
 * Parses blocks out of a content string, and renders those appropriate for the excerpt.
 *
 * As the excerpt should be a small string of text relevant to the full post content,
 * this function renders the blocks that are most likely to contain such text.
 *
 * @since 5.0.0
 *
 * @param string $content The content to parse.
 * @return string The parsed and filtered content.
 */
function excerpt_remove_blocks( $content ) {
	if ( ! has_blocks( $content ) ) {
		return $content;
	}

	$allowed_inner_blocks = array(
		// Classic blocks have their blockName set to null.
		null,
		'core/freeform',
		'core/heading',
		'core/html',
		'core/list',
		'core/media-text',
		'core/paragraph',
		'core/preformatted',
		'core/pullquote',
		'core/quote',
		'core/table',
		'core/verse',
	);

	$allowed_wrapper_blocks = array(
		'core/columns',
		'core/column',
		'core/group',
	);

	/**
	 * Filters the list of blocks that can be used as wrapper blocks, allowing
	 * excerpts to be generated from the `innerBlocks` of these wrappers.
	 *
	 * @since 5.8.0
	 *
	 * @param string[] $allowed_wrapper_blocks The list of names of allowed wrapper blocks.
	 */
	$allowed_wrapper_blocks = apply_filters( 'excerpt_allowed_wrapper_blocks', $allowed_wrapper_blocks );

	$allowed_blocks = array_merge( $allowed_inner_blocks, $allowed_wrapper_blocks );

	/**
	 * Filters the list of blocks that can contribute to the excerpt.
	 *
	 * If a dynamic block is added to this list, it must not generate another
	 * excerpt, as this will cause an infinite loop to occur.
	 *
	 * @since 5.0.0
	 *
	 * @param string[] $allowed_blocks The list of names of allowed blocks.
	 */
	$allowed_blocks = apply_filters( 'excerpt_allowed_blocks', $allowed_blocks );
	$blocks         = parse_blocks( $content );
	$output         = '';

	foreach ( $blocks as $block ) {
		if ( in_array( $block['blockName'], $allowed_blocks, true ) ) {
			if ( ! empty( $block['innerBlocks'] ) ) {
				if ( in_array( $block['blockName'], $allowed_wrapper_blocks, true ) ) {
					$output .= _excerpt_render_inner_blocks( $block, $allowed_blocks );
					continue;
				}

				// Skip the block if it has disallowed or nested inner blocks.
				foreach ( $block['innerBlocks'] as $inner_block ) {
					if (
						! in_array( $inner_block['blockName'], $allowed_inner_blocks, true ) ||
						! empty( $inner_block['innerBlocks'] )
					) {
						continue 2;
					}
				}
			}

			$output .= render_block( $block );
		}
	}

	return $output;
}

/**
 * Parses footnotes markup out of a content string,
 * and renders those appropriate for the excerpt.
 *
 * @since 6.3.0
 *
 * @param string $content The content to parse.
 * @return string The parsed and filtered content.
 */
function excerpt_remove_footnotes( $content ) {
	if ( ! str_contains( $content, 'data-fn=' ) ) {
		return $content;
	}

	return preg_replace(
		'_<sup data-fn="[^"]+" class="[^"]+">\s*<a href="[^"]+" id="[^"]+">\d+</a>\s*</sup>_',
		'',
		$content
	);
}

/**
 * Renders inner blocks from the allowed wrapper blocks
 * for generating an excerpt.
 *
 * @since 5.8.0
 * @access private
 *
 * @param array $parsed_block   The parsed block.
 * @param array $allowed_blocks The list of allowed inner blocks.
 * @return string The rendered inner blocks.
 */
function _excerpt_render_inner_blocks( $parsed_block, $allowed_blocks ) {
	$output = '';

	foreach ( $parsed_block['innerBlocks'] as $inner_block ) {
		if ( ! in_array( $inner_block['blockName'], $allowed_blocks, true ) ) {
			continue;
		}

		if ( empty( $inner_block['innerBlocks'] ) ) {
			$output .= render_block( $inner_block );
		} else {
			$output .= _excerpt_render_inner_blocks( $inner_block, $allowed_blocks );
		}
	}

	return $output;
}

/**
 * Renders a single block into a HTML string.
 *
 * @since 5.0.0
 *
 * @global WP_Post $post The post to edit.
 *
 * @param array $parsed_block {
 *     An associative array of the block being rendered. See WP_Block_Parser_Block.
 *
 *     @type string   $blockName    Name of block.
 *     @type array    $attrs        Attributes from block comment delimiters.
 *     @type array[]  $innerBlocks  List of inner blocks. An array of arrays that
 *                                  have the same structure as this one.
 *     @type string   $innerHTML    HTML from inside block comment delimiters.
 *     @type array    $innerContent List of string fragments and null markers where
 *                                  inner blocks were found.
 * }
 * @return string String of rendered HTML.
 */
function render_block( $parsed_block ) {
	global $post;
	$parent_block = null;

	/**
	 * Allows render_block() to be short-circuited, by returning a non-null value.
	 *
	 * @since 5.1.0
	 * @since 5.9.0 The `$parent_block` parameter was added.
	 *
	 * @param string|null   $pre_render   The pre-rendered content. Default null.
	 * @param array         $parsed_block {
	 *     An associative array of the block being rendered. See WP_Block_Parser_Block.
	 *
	 *     @type string   $blockName    Name of block.
	 *     @type array    $attrs        Attributes from block comment delimiters.
	 *     @type array[]  $innerBlocks  List of inner blocks. An array of arrays that
	 *                                  have the same structure as this one.
	 *     @type string   $innerHTML    HTML from inside block comment delimiters.
	 *     @type array    $innerContent List of string fragments and null markers where
	 *                                  inner blocks were found.
	 * }
	 * @param WP_Block|null $parent_block If this is a nested block, a reference to the parent block.
	 */
	$pre_render = apply_filters( 'pre_render_block', null, $parsed_block, $parent_block );
	if ( ! is_null( $pre_render ) ) {
		return $pre_render;
	}

	$source_block = $parsed_block;

	/**
	 * Filters the block being rendered in render_block(), before it's processed.
	 *
	 * @since 5.1.0
	 * @since 5.9.0 The `$parent_block` parameter was added.
	 *
	 * @param array         $parsed_block {
	 *     An associative array of the block being rendered. See WP_Block_Parser_Block.
	 *
	 *     @type string   $blockName    Name of block.
	 *     @type array    $attrs        Attributes from block comment delimiters.
	 *     @type array[]  $innerBlocks  List of inner blocks. An array of arrays that
	 *                                  have the same structure as this one.
	 *     @type string   $innerHTML    HTML from inside block comment delimiters.
	 *     @type array    $innerContent List of string fragments and null markers where
	 *                                  inner blocks were found.
	 * }
	 * @param array         $source_block {
	 *     An un-modified copy of `$parsed_block`, as it appeared in the source content.
	 *     See WP_Block_Parser_Block.
	 *
	 *     @type string   $blockName    Name of block.
	 *     @type array    $attrs        Attributes from block comment delimiters.
	 *     @type array[]  $innerBlocks  List of inner blocks. An array of arrays that
	 *                                  have the same structure as this one.
	 *     @type string   $innerHTML    HTML from inside block comment delimiters.
	 *     @type array    $innerContent List of string fragments and null markers where
	 *                                  inner blocks were found.
	 * }
	 * @param WP_Block|null $parent_block If this is a nested block, a reference to the parent block.
	 */
	$parsed_block = apply_filters( 'render_block_data', $parsed_block, $source_block, $parent_block );

	$context = array();

	if ( $post instanceof WP_Post ) {
		$context['postId'] = $post->ID;

		/*
		 * The `postType` context is largely unnecessary server-side, since the ID
		 * is usually sufficient on its own. That being said, since a block's
		 * manifest is expected to be shared between the server and the client,
		 * it should be included to consistently fulfill the expectation.
		 */
		$context['postType'] = $post->post_type;
	}

	/**
	 * Filters the default context provided to a rendered block.
	 *
	 * @since 5.5.0
	 * @since 5.9.0 The `$parent_block` parameter was added.
	 *
	 * @param array         $context      Default context.
	 * @param array         $parsed_block {
	 *     An associative array of the block being rendered. See WP_Block_Parser_Block.
	 *
	 *     @type string   $blockName    Name of block.
	 *     @type array    $attrs        Attributes from block comment delimiters.
	 *     @type array[]  $innerBlocks  List of inner blocks. An array of arrays that
	 *                                  have the same structure as this one.
	 *     @type string   $innerHTML    HTML from inside block comment delimiters.
	 *     @type array    $innerContent List of string fragments and null markers where
	 *                                  inner blocks were found.
	 * }
	 * @param WP_Block|null $parent_block If this is a nested block, a reference to the parent block.
	 */
	$context = apply_filters( 'render_block_context', $context, $parsed_block, $parent_block );

	$block = new WP_Block( $parsed_block, $context );

	return $block->render();
}

/**
 * Parses blocks out of a content string.
 *
 * @since 5.0.0
 *
 * @param string $content Post content.
 * @return array[] {
 *     Array of block structures.
 *
 *     @type array ...$0 {
 *         An associative array of a single parsed block object. See WP_Block_Parser_Block.
 *
 *         @type string   $blockName    Name of block.
 *         @type array    $attrs        Attributes from block comment delimiters.
 *         @type array[]  $innerBlocks  List of inner blocks. An array of arrays that
 *                                      have the same structure as this one.
 *         @type string   $innerHTML    HTML from inside block comment delimiters.
 *         @type array    $innerContent List of string fragments and null markers where
 *                                      inner blocks were found.
 *     }
 * }
 */
function parse_blocks( $content ) {
	/**
	 * Filter to allow plugins to replace the server-side block parser.
	 *
	 * @since 5.0.0
	 *
	 * @param string $parser_class Name of block parser class.
	 */
	$parser_class = apply_filters( 'block_parser_class', 'WP_Block_Parser' );

	$parser = new $parser_class();
	return $parser->parse( $content );
}

/**
 * Parses dynamic blocks out of `post_content` and re-renders them.
 *
 * @since 5.0.0
 *
 * @param string $content Post content.
 * @return string Updated post content.
 */
function do_blocks( $content ) {
	$blocks = parse_blocks( $content );
	$output = '';

	foreach ( $blocks as $block ) {
		$output .= render_block( $block );
	}

	// If there are blocks in this content, we shouldn't run wpautop() on it later.
	$priority = has_filter( 'the_content', 'wpautop' );
	if ( false !== $priority && doing_filter( 'the_content' ) && has_blocks( $content ) ) {
		remove_filter( 'the_content', 'wpautop', $priority );
		add_filter( 'the_content', '_restore_wpautop_hook', $priority + 1 );
	}

	return $output;
}

/**
 * If do_blocks() needs to remove wpautop() from the `the_content` filter, this re-adds it afterwards,
 * for subsequent `the_content` usage.
 *
 * @since 5.0.0
 * @access private
 *
 * @param string $content The post content running through this filter.
 * @return string The unmodified content.
 */
function _restore_wpautop_hook( $content ) {
	$current_priority = has_filter( 'the_content', '_restore_wpautop_hook' );

	add_filter( 'the_content', 'wpautop', $current_priority - 1 );
	remove_filter( 'the_content', '_restore_wpautop_hook', $current_priority );

	return $content;
}

/**
 * Returns the current version of the block format that the content string is using.
 *
 * If the string doesn't contain blocks, it returns 0.
 *
 * @since 5.0.0
 *
 * @param string $content Content to test.
 * @return int The block format version is 1 if the content contains one or more blocks, 0 otherwise.
 */
function block_version( $content ) {
	return has_blocks( $content ) ? 1 : 0;
}

/**
 * Registers a new block style.
 *
 * @since 5.3.0
 * @since 6.6.0 Added support for registering styles for multiple block types.
 *
 * @link https://developer.wordpress.org/block-editor/reference-guides/block-api/block-styles/
 *
 * @param string|string[] $block_name       Block type name including namespace or array of namespaced block type names.
 * @param array           $style_properties Array containing the properties of the style name, label,
 *                                          style_handle (name of the stylesheet to be enqueued),
 *                                          inline_style (string containing the CSS to be added),
 *                                          style_data (theme.json-like array to generate CSS from).
 *                                          See WP_Block_Styles_Registry::register().
 * @return bool True if the block style was registered with success and false otherwise.
 */
function register_block_style( $block_name, $style_properties ) {
	return WP_Block_Styles_Registry::get_instance()->register( $block_name, $style_properties );
}

/**
 * Unregisters a block style.
 *
 * @since 5.3.0
 *
 * @param string $block_name       Block type name including namespace.
 * @param string $block_style_name Block style name.
 * @return bool True if the block style was unregistered with success and false otherwise.
 */
function unregister_block_style( $block_name, $block_style_name ) {
	return WP_Block_Styles_Registry::get_instance()->unregister( $block_name, $block_style_name );
}

/**
 * Checks whether the current block type supports the feature requested.
 *
 * @since 5.8.0
 * @since 6.4.0 The `$feature` parameter now supports a string.
 *
 * @param WP_Block_Type $block_type    Block type to check for support.
 * @param string|array  $feature       Feature slug, or path to a specific feature to check support for.
 * @param mixed         $default_value Optional. Fallback value for feature support. Default false.
 * @return bool Whether the feature is supported.
 */
function block_has_support( $block_type, $feature, $default_value = false ) {
	$block_support = $default_value;
	if ( $block_type instanceof WP_Block_Type ) {
		if ( is_array( $feature ) && count( $feature ) === 1 ) {
			$feature = $feature[0];
		}

		if ( is_array( $feature ) ) {
			$block_support = _wp_array_get( $block_type->supports, $feature, $default_value );
		} elseif ( isset( $block_type->supports[ $feature ] ) ) {
			$block_support = $block_type->supports[ $feature ];
		}
	}

	return true === $block_support || is_array( $block_support );
}

/**
 * Converts typography keys declared under `supports.*` to `supports.typography.*`.
 *
 * Displays a `_doing_it_wrong()` notice when a block using the older format is detected.
 *
 * @since 5.8.0
 *
 * @param array $metadata Metadata for registering a block type.
 * @return array Filtered metadata for registering a block type.
 */
function wp_migrate_old_typography_shape( $metadata ) {
	if ( ! isset( $metadata['supports'] ) ) {
		return $metadata;
	}

	$typography_keys = array(
		'__experimentalFontFamily',
		'__experimentalFontStyle',
		'__experimentalFontWeight',
		'__experimentalLetterSpacing',
		'__experimentalTextDecoration',
		'__experimentalTextTransform',
		'fontSize',
		'lineHeight',
	);

	foreach ( $typography_keys as $typography_key ) {
		$support_for_key = isset( $metadata['supports'][ $typography_key ] ) ? $metadata['supports'][ $typography_key ] : null;

		if ( null !== $support_for_key ) {
			_doing_it_wrong(
				'register_block_type_from_metadata()',
				sprintf(
					/* translators: 1: Block type, 2: Typography supports key, e.g: fontSize, lineHeight, etc. 3: block.json, 4: Old metadata key, 5: New metadata key. */
					__( 'Block "%1$s" is declaring %2$s support in %3$s file under %4$s. %2$s support is now declared under %5$s.' ),
					$metadata['name'],
					"<code>$typography_key</code>",
					'<code>block.json</code>',
					"<code>supports.$typography_key</code>",
					"<code>supports.typography.$typography_key</code>"
				),
				'5.8.0'
			);

			_wp_array_set( $metadata['supports'], array( 'typography', $typography_key ), $support_for_key );
			unset( $metadata['supports'][ $typography_key ] );
		}
	}

	return $metadata;
}

/**
 * Helper function that constructs a WP_Query args array from
 * a `Query` block properties.
 *
 * It's used in Query Loop, Query Pagination Numbers and Query Pagination Next blocks.
 *
 * @since 5.8.0
 * @since 6.1.0 Added `query_loop_block_query_vars` filter and `parents` support in query.
 * @since 6.7.0 Added support for the `format` property in query.
 *
 * @param WP_Block $block Block instance.
 * @param int      $page  Current query's page.
 *
 * @return array Returns the constructed WP_Query arguments.
 */
function build_query_vars_from_query_block( $block, $page ) {
	$query = array(
		'post_type'    => 'post',
		'order'        => 'DESC',
		'orderby'      => 'date',
		'post__not_in' => array(),
		'tax_query'    => array(),
	);

	if ( isset( $block->context['query'] ) ) {
		if ( ! empty( $block->context['query']['postType'] ) ) {
			$post_type_param = $block->context['query']['postType'];
			if ( is_post_type_viewable( $post_type_param ) ) {
				$query['post_type'] = $post_type_param;
			}
		}
		if ( isset( $block->context['query']['sticky'] ) && ! empty( $block->context['query']['sticky'] ) ) {
			$sticky = get_option( 'sticky_posts' );
			if ( 'only' === $block->context['query']['sticky'] ) {
				/*
				 * Passing an empty array to post__in will return have_posts() as true (and all posts will be returned).
				 * Logic should be used before hand to determine if WP_Query should be used in the event that the array
				 * being passed to post__in is empty.
				 *
				 * @see https://core.trac.wordpress.org/ticket/28099
				 */
				$query['post__in']            = ! empty( $sticky ) ? $sticky : array( 0 );
				$query['ignore_sticky_posts'] = 1;
			} else {
				$query['post__not_in'] = array_merge( $query['post__not_in'], $sticky );
			}
		}
		if ( ! empty( $block->context['query']['exclude'] ) ) {
			$excluded_post_ids     = array_map( 'intval', $block->context['query']['exclude'] );
			$excluded_post_ids     = array_filter( $excluded_post_ids );
			$query['post__not_in'] = array_merge( $query['post__not_in'], $excluded_post_ids );
		}
		if (
			isset( $block->context['query']['perPage'] ) &&
			is_numeric( $block->context['query']['perPage'] )
		) {
			$per_page = absint( $block->context['query']['perPage'] );
			$offset   = 0;

			if (
				isset( $block->context['query']['offset'] ) &&
				is_numeric( $block->context['query']['offset'] )
			) {
				$offset = absint( $block->context['query']['offset'] );
			}

			$query['offset']         = ( $per_page * ( $page - 1 ) ) + $offset;
			$query['posts_per_page'] = $per_page;
		}
		// Migrate `categoryIds` and `tagIds` to `tax_query` for backwards compatibility.
		if ( ! empty( $block->context['query']['categoryIds'] ) || ! empty( $block->context['query']['tagIds'] ) ) {
			$tax_query_back_compat = array();
			if ( ! empty( $block->context['query']['categoryIds'] ) ) {
				$tax_query_back_compat[] = array(
					'taxonomy'         => 'category',
					'terms'            => array_filter( array_map( 'intval', $block->context['query']['categoryIds'] ) ),
					'include_children' => false,
				);
			}
			if ( ! empty( $block->context['query']['tagIds'] ) ) {
				$tax_query_back_compat[] = array(
					'taxonomy'         => 'post_tag',
					'terms'            => array_filter( array_map( 'intval', $block->context['query']['tagIds'] ) ),
					'include_children' => false,
				);
			}
			$query['tax_query'] = array_merge( $query['tax_query'], $tax_query_back_compat );
		}
		if ( ! empty( $block->context['query']['taxQuery'] ) ) {
			$tax_query = array();
			foreach ( $block->context['query']['taxQuery'] as $taxonomy => $terms ) {
				if ( is_taxonomy_viewable( $taxonomy ) && ! empty( $terms ) ) {
					$tax_query[] = array(
						'taxonomy'         => $taxonomy,
						'terms'            => array_filter( array_map( 'intval', $terms ) ),
						'include_children' => false,
					);
				}
			}
			$query['tax_query'] = array_merge( $query['tax_query'], $tax_query );
		}
		if ( ! empty( $block->context['query']['format'] ) && is_array( $block->context['query']['format'] ) ) {
			$formats = $block->context['query']['format'];
			/*
			 * Validate that the format is either `standard` or a supported post format.
			 * - First, add `standard` to the array of valid formats.
			 * - Then, remove any invalid formats.
			 */
			$valid_formats = array_merge( array( 'standard' ), get_post_format_slugs() );
			$formats       = array_intersect( $formats, $valid_formats );

			/*
			 * The relation needs to be set to `OR` since the request can contain
			 * two separate conditions. The user may be querying for items that have
			 * either the `standard` format or a specific format.
			 */
			$formats_query = array( 'relation' => 'OR' );

			/*
			 * The default post format, `standard`, is not stored in the database.
			 * If `standard` is part of the request, the query needs to exclude all post items that
			 * have a format assigned.
			 */
			if ( in_array( 'standard', $formats, true ) ) {
				$formats_query[] = array(
					'taxonomy' => 'post_format',
					'field'    => 'slug',
					'operator' => 'NOT EXISTS',
				);
				// Remove the `standard` format, since it cannot be queried.
				unset( $formats[ array_search( 'standard', $formats, true ) ] );
			}
			// Add any remaining formats to the formats query.
			if ( ! empty( $formats ) ) {
				// Add the `post-format-` prefix.
				$terms           = array_map(
					static function ( $format ) {
						return "post-format-$format";
					},
					$formats
				);
				$formats_query[] = array(
					'taxonomy' => 'post_format',
					'field'    => 'slug',
					'terms'    => $terms,
					'operator' => 'IN',
				);
			}

			/*
			 * Add `$formats_query` to `$query`, as long as it contains more than one key:
			 * If `$formats_query` only contains the initial `relation` key, there are no valid formats to query,
			 * and the query should not be modified.
			 */
			if ( count( $formats_query ) > 1 ) {
				// Enable filtering by both post formats and other taxonomies by combining them with `AND`.
				if ( empty( $query['tax_query'] ) ) {
					$query['tax_query'] = $formats_query;
				} else {
					$query['tax_query'] = array(
						'relation' => 'AND',
						$query['tax_query'],
						$formats_query,
					);
				}
			}
		}

		if (
			isset( $block->context['query']['order'] ) &&
				in_array( strtoupper( $block->context['query']['order'] ), array( 'ASC', 'DESC' ), true )
		) {
			$query['order'] = strtoupper( $block->context['query']['order'] );
		}
		if ( isset( $block->context['query']['orderBy'] ) ) {
			$query['orderby'] = $block->context['query']['orderBy'];
		}
		if (
			isset( $block->context['query']['author'] )
		) {
			if ( is_array( $block->context['query']['author'] ) ) {
				$query['author__in'] = array_filter( array_map( 'intval', $block->context['query']['author'] ) );
			} elseif ( is_string( $block->context['query']['author'] ) ) {
				$query['author__in'] = array_filter( array_map( 'intval', explode( ',', $block->context['query']['author'] ) ) );
			} elseif ( is_int( $block->context['query']['author'] ) && $block->context['query']['author'] > 0 ) {
				$query['author'] = $block->context['query']['author'];
			}
		}
		if ( ! empty( $block->context['query']['search'] ) ) {
			$query['s'] = $block->context['query']['search'];
		}
		if ( ! empty( $block->context['query']['parents'] ) && is_post_type_hierarchical( $query['post_type'] ) ) {
			$query['post_parent__in'] = array_filter( array_map( 'intval', $block->context['query']['parents'] ) );
		}
	}

	/**
	 * Filters the arguments which will be passed to `WP_Query` for the Query Loop Block.
	 *
	 * Anything to this filter should be compatible with the `WP_Query` API to form
	 * the query context which will be passed down to the Query Loop Block's children.
	 * This can help, for example, to include additional settings or meta queries not
	 * directly supported by the core Query Loop Block, and extend its capabilities.
	 *
	 * Please note that this will only influence the query that will be rendered on the
	 * front-end. The editor preview is not affected by this filter. Also, worth noting
	 * that the editor preview uses the REST API, so, ideally, one should aim to provide
	 * attributes which are also compatible with the REST API, in order to be able to
	 * implement identical queries on both sides.
	 *
	 * @since 6.1.0
	 *
	 * @param array    $query Array containing parameters for `WP_Query` as parsed by the block context.
	 * @param WP_Block $block Block instance.
	 * @param int      $page  Current query's page.
	 */
	return apply_filters( 'query_loop_block_query_vars', $query, $block, $page );
}

/**
 * Helper function that returns the proper pagination arrow HTML for
 * `QueryPaginationNext` and `QueryPaginationPrevious` blocks based
 * on the provided `paginationArrow` from `QueryPagination` context.
 *
 * It's used in QueryPaginationNext and QueryPaginationPrevious blocks.
 *
 * @since 5.9.0
 *
 * @param WP_Block $block   Block instance.
 * @param bool     $is_next Flag for handling `next/previous` blocks.
 * @return string|null The pagination arrow HTML or null if there is none.
 */
function get_query_pagination_arrow( $block, $is_next ) {
	$arrow_map = array(
		'none'    => '',
		'arrow'   => array(
			'next'     => '→',
			'previous' => '←',
		),
		'chevron' => array(
			'next'     => '»',
			'previous' => '«',
		),
	);
	if ( ! empty( $block->context['paginationArrow'] ) && array_key_exists( $block->context['paginationArrow'], $arrow_map ) && ! empty( $arrow_map[ $block->context['paginationArrow'] ] ) ) {
		$pagination_type = $is_next ? 'next' : 'previous';
		$arrow_attribute = $block->context['paginationArrow'];
		$arrow           = $arrow_map[ $block->context['paginationArrow'] ][ $pagination_type ];
		$arrow_classes   = "wp-block-query-pagination-$pagination_type-arrow is-arrow-$arrow_attribute";
		return "<span class='$arrow_classes' aria-hidden='true'>$arrow</span>";
	}
	return null;
}

/**
 * Helper function that constructs a comment query vars array from the passed
 * block properties.
 *
 * It's used with the Comment Query Loop inner blocks.
 *
 * @since 6.0.0
 *
 * @param WP_Block $block Block instance.
 * @return array Returns the comment query parameters to use with the
 *               WP_Comment_Query constructor.
 */
function build_comment_query_vars_from_block( $block ) {

	$comment_args = array(
		'orderby'       => 'comment_date_gmt',
		'order'         => 'ASC',
		'status'        => 'approve',
		'no_found_rows' => false,
	);

	if ( is_user_logged_in() ) {
		$comment_args['include_unapproved'] = array( get_current_user_id() );
	} else {
		$unapproved_email = wp_get_unapproved_comment_author_email();

		if ( $unapproved_email ) {
			$comment_args['include_unapproved'] = array( $unapproved_email );
		}
	}

	if ( ! empty( $block->context['postId'] ) ) {
		$comment_args['post_id'] = (int) $block->context['postId'];
	}

	if ( get_option( 'thread_comments' ) ) {
		$comment_args['hierarchical'] = 'threaded';
	} else {
		$comment_args['hierarchical'] = false;
	}

	if ( get_option( 'page_comments' ) === '1' || get_option( 'page_comments' ) === true ) {
		$per_page     = get_option( 'comments_per_page' );
		$default_page = get_option( 'default_comments_page' );
		if ( $per_page > 0 ) {
			$comment_args['number'] = $per_page;

			$page = (int) get_query_var( 'cpage' );
			if ( $page ) {
				$comment_args['paged'] = $page;
			} elseif ( 'oldest' === $default_page ) {
				$comment_args['paged'] = 1;
			} elseif ( 'newest' === $default_page ) {
				$max_num_pages = (int) ( new WP_Comment_Query( $comment_args ) )->max_num_pages;
				if ( 0 !== $max_num_pages ) {
					$comment_args['paged'] = $max_num_pages;
				}
			}
		}
	}

	return $comment_args;
}

/**
 * Helper function that returns the proper pagination arrow HTML for
 * `CommentsPaginationNext` and `CommentsPaginationPrevious` blocks based on the
 * provided `paginationArrow` from `CommentsPagination` context.
 *
 * It's used in CommentsPaginationNext and CommentsPaginationPrevious blocks.
 *
 * @since 6.0.0
 *
 * @param WP_Block $block           Block instance.
 * @param string   $pagination_type Optional. Type of the arrow we will be rendering.
 *                                  Accepts 'next' or 'previous'. Default 'next'.
 * @return string|null The pagination arrow HTML or null if there is none.
 */
function get_comments_pagination_arrow( $block, $pagination_type = 'next' ) {
	$arrow_map = array(
		'none'    => '',
		'arrow'   => array(
			'next'     => '→',
			'previous' => '←',
		),
		'chevron' => array(
			'next'     => '»',
			'previous' => '«',
		),
	);
	if ( ! empty( $block->context['comments/paginationArrow'] ) && ! empty( $arrow_map[ $block->context['comments/paginationArrow'] ][ $pagination_type ] ) ) {
		$arrow_attribute = $block->context['comments/paginationArrow'];
		$arrow           = $arrow_map[ $block->context['comments/paginationArrow'] ][ $pagination_type ];
		$arrow_classes   = "wp-block-comments-pagination-$pagination_type-arrow is-arrow-$arrow_attribute";
		return "<span class='$arrow_classes' aria-hidden='true'>$arrow</span>";
	}
	return null;
}

/**
 * Strips all HTML from the content of footnotes, and sanitizes the ID.
 *
 * This function expects slashed data on the footnotes content.
 *
 * @access private
 * @since 6.3.2
 *
 * @param string $footnotes JSON-encoded string of an array containing the content and ID of each footnote.
 * @return string Filtered content without any HTML on the footnote content and with the sanitized ID.
 */
function _wp_filter_post_meta_footnotes( $footnotes ) {
	$footnotes_decoded = json_decode( $footnotes, true );
	if ( ! is_array( $footnotes_decoded ) ) {
		return '';
	}
	$footnotes_sanitized = array();
	foreach ( $footnotes_decoded as $footnote ) {
		if ( ! empty( $footnote['content'] ) && ! empty( $footnote['id'] ) ) {
			$footnotes_sanitized[] = array(
				'id'      => sanitize_key( $footnote['id'] ),
				'content' => wp_unslash( wp_filter_post_kses( wp_slash( $footnote['content'] ) ) ),
			);
		}
	}
	return wp_json_encode( $footnotes_sanitized );
}

/**
 * Adds the filters for footnotes meta field.
 *
 * @access private
 * @since 6.3.2
 */
function _wp_footnotes_kses_init_filters() {
	add_filter( 'sanitize_post_meta_footnotes', '_wp_filter_post_meta_footnotes' );
}

/**
 * Removes the filters for footnotes meta field.
 *
 * @access private
 * @since 6.3.2
 */
function _wp_footnotes_remove_filters() {
	remove_filter( 'sanitize_post_meta_footnotes', '_wp_filter_post_meta_footnotes' );
}

/**
 * Registers the filter of footnotes meta field if the user does not have `unfiltered_html` capability.
 *
 * @access private
 * @since 6.3.2
 */
function _wp_footnotes_kses_init() {
	_wp_footnotes_remove_filters();
	if ( ! current_user_can( 'unfiltered_html' ) ) {
		_wp_footnotes_kses_init_filters();
	}
}

/**
 * Initializes the filters for footnotes meta field when imported data should be filtered.
 *
 * This filter is the last one being executed on {@see 'force_filtered_html_on_import'}.
 * If the input of the filter is true, it means we are in an import situation and should
 * enable kses, independently of the user capabilities. So in that case we call
 * _wp_footnotes_kses_init_filters().
 *
 * @access private
 * @since 6.3.2
 *
 * @param string $arg Input argument of the filter.
 * @return string Input argument of the filter.
 */
function _wp_footnotes_force_filtered_html_on_import_filter( $arg ) {
	// If `force_filtered_html_on_import` is true, we need to init the global styles kses filters.
	if ( $arg ) {
		_wp_footnotes_kses_init_filters();
	}
	return $arg;
}