$text Text to insert.
				 */
				public function insert_before( string $text ): void {
					$this->lexical_updates[] = new WP_HTML_Text_Replacement( $this->get_span()->start, 0, $text );
				}

				/**
				 * Inserts text after the current token.
				 *
				 * @param string $text Text to insert.
				 */
				public function insert_after( string $text ): void {
					$span = $this->get_span();

					$this->lexical_updates[] = new WP_HTML_Text_Replacement( $span->start + $span->length, 0, $text );
				}

				/**
				 * Removes the current token.
				 */
				public function remove(): void {
					$span = $this->get_span();

					$this->lexical_updates[] = new WP_HTML_Text_Replacement( $span->start, $span->length, '' );
				}

				/**
				 * Replaces the current token.
				 *
				 * @param string $text Text to replace with.
				 */
				public function replace( string $text ): void {
					$span = $this->get_span();

					$this->lexical_updates[] = new WP_HTML_Text_Replacement( $span->start, $span->length, $text );
				}
			};

			// Locate the insertion points in the HEAD.
			while ( $processor->next_tag( array( 'tag_closers' => 'visit' ) ) ) {
				if (
					'STYLE' === $processor->get_tag() &&
					'wp-global-styles-placeholder-inline-css' === $processor->get_attribute( 'id' )
				) {
					/** This is added in {@see wp_enqueue_global_styles()} */
					$processor->set_bookmark( 'wp_global_styles_placeholder' );
				} elseif (
					'STYLE' === $processor->get_tag() &&
					'wp-block-styles-placeholder-inline-css' === $processor->get_attribute( 'id' )
				) {
					/** This is added in {@see wp_enqueue_registered_block_scripts_and_styles()} */
					$processor->set_bookmark( 'wp_block_styles_placeholder' );
				} elseif (
					'STYLE' === $processor->get_tag() &&
					'wp-block-library-inline-css' === $processor->get_attribute( 'id' )
				) {
					/** This is added here in {@see wp_hoist_late_printed_styles()} */
					$processor->set_bookmark( 'wp_block_library' );
				} elseif ( 'HEAD' === $processor->get_tag() && $processor->is_tag_closer() ) {
					$processor->set_bookmark( 'head_end' );
					break;
				}
			}

			/**
			 * Replace the placeholder for global styles enqueued during {@see wp_enqueue_global_styles()}. This is done
			 * even if $printed_global_styles is empty.
			 */
			if ( $processor->has_bookmark( 'wp_global_styles_placeholder' ) ) {
				$processor->seek( 'wp_global_styles_placeholder' );
				$processor->replace( $printed_global_styles );
				$printed_global_styles = '';
			}

			/*
			 * Insert block styles right after wp-block-library (if it is present). The placeholder CSS comment will
			 * always be added to the wp-block-library inline style since it gets printed at `wp_head` before the blocks
			 * are rendered. This means that there may not actually be any block styles to hoist from the footer to
			 * insert after this inline style. The placeholder CSS comment needs to be added so that the inline style
			 * gets printed, but if the resulting inline style is empty after the placeholder is removed, then the
			 * inline style is removed.
			 */
			if ( $processor->has_bookmark( 'wp_block_library' ) ) {
				$processor->seek( 'wp_block_library' );

				$css_text = $processor->get_modifiable_text();

				/*
				 * Split the block library inline style by the placeholder to identify the original inlined CSS, which
				 * likely would be common.css, followed by any inline styles which had been added by the theme or
				 * plugins via `wp_add_inline_style( 'wp-block-library', '...' )`. The separate block styles loaded on
				 * demand will get inserted after the inlined common.css and before the extra inline styles added by the
				 * user.
				 */
				$css_text_around_placeholder = explode( $placeholder, $css_text, 2 );
				$extra_inline_styles         = '';
				if ( count( $css_text_around_placeholder ) === 2 ) {
					$css_text = $css_text_around_placeholder[0];
					if ( '' !== trim( $css_text ) ) {
						$inlined_src = wp_styles()->get_data( 'wp-block-library', 'inlined_src' );
						if ( $inlined_src ) {
							$css_text .= sprintf(
								"\n/*# sourceURL=%s */\n",
								esc_url_raw( $inlined_src )
							);
						}
					}
					$extra_inline_styles = $css_text_around_placeholder[1];
				}

				/*
				 * The placeholder CSS comment was added to the inline style in order to force an inline STYLE tag to
				 * be printed. Now that the inline style has been located and the placeholder comment has been removed, if
				 * there is no CSS left in the STYLE tag after removal, then remove the STYLE tag entirely.
				 */
				if ( '' === trim( $css_text ) ) {
					$processor->remove();
				} else {
					$processor->set_modifiable_text( $css_text );
				}

				$inserted_after            = $printed_core_block_styles;
				$printed_core_block_styles = '';

				/*
				 * Add a new inline style for any user styles added via wp_add_inline_style( 'wp-block-library', '...' ).
				 * This must be added here after $printed_core_block_styles to preserve the original CSS cascade when
				 * the combined block library stylesheet was used. The pattern here is checking to see if it is not just
				 * a sourceURL comment after the placeholder above is removed.
				 */
				if ( ! preg_match( ':^\s*(/\*# sourceURL=\S+? \*/\s*)?$:s', $extra_inline_styles ) ) {
					$style_processor = new WP_HTML_Tag_Processor( '<style></style>' );
					$style_processor->next_tag();
					$style_processor->set_attribute( 'id', 'wp-block-library-inline-css-extra' );
					$style_processor->set_modifiable_text( $extra_inline_styles );
					$inserted_after .= "{$style_processor->get_updated_html()}\n";
				}

				if ( '' !== $inserted_after ) {
					$processor->insert_after( "\n" . $inserted_after );
				}
			}

			// Insert block styles at the point where wp_enqueue_registered_block_scripts_and_styles() normally enqueues styles.
			if ( $processor->has_bookmark( 'wp_block_styles_placeholder' ) ) {
				$processor->seek( 'wp_block_styles_placeholder' );
				if ( '' !== $printed_other_block_styles ) {
					$processor->replace( "\n" . $printed_other_block_styles );
				} else {
					$processor->remove();
				}
				$printed_other_block_styles = '';
			}

			// Print all remaining styles.
			$remaining_styles = $printed_core_block_styles . $printed_other_block_styles . $printed_global_styles . $printed_late_styles;
			if ( $remaining_styles && $processor->has_bookmark( 'head_end' ) ) {
				$processor->seek( 'head_end' );
				$processor->insert_before( $remaining_styles . "\n" );
			}
			return $processor->get_updated_html();
		}
	);
}

/**
 * Return the corresponding JavaScript `dataset` name for an attribute
 * if it represents a custom data attribute, or `null` if not.
 *
 * Custom data attributes appear in an element's `dataset` property in a
 * browser, but there's a specific way the names are translated from HTML
 * into JavaScript. This function indicates how the name would appear in
 * JavaScript if a browser would recognize it as a custom data attribute.
 *
 * Example:
 *
 *     // Dash-letter pairs turn into capital letters.
 *     'postId'       === wp_js_dataset_name( 'data-post-id' );
 *     'Before'       === wp_js_dataset_name( 'data--before' );
 *     '-One--Two---' === wp_js_dataset_name( 'data---one---two---' );
 *
 *     // Not every attribute name will be interpreted as a custom data attribute.
 *     null === wp_js_dataset_name( 'post-id' );
 *     null === wp_js_dataset_name( 'data' );
 *
 *     // Some very surprising names will; for example, a property whose name is the empty string.
 *     '' === wp_js_dataset_name( 'data-' );
 *     0  === strlen( wp_js_dataset_name( 'data-' ) );
 *
 * @since 6.9.0
 *
 * @see https://html.spec.whatwg.org/#concept-domstringmap-pairs
 * @see \wp_html_custom_data_attribute_name()
 *
 * @param string $html_attribute_name Raw attribute name as found in the source HTML.
 * @return string|null Transformed `dataset` name, if interpretable as a custom data attribute, else `null`.
 */
function wp_js_dataset_name( string $html_attribute_name ): ?string {
	if ( 0 !== substr_compare( $html_attribute_name, 'data-', 0, 5, true ) ) {
		return null;
	}

	$end = strlen( $html_attribute_name );

	/*
	 * If it contains characters which would end the attribute name parsing then
	 * something else is wrong and this contains more than just an attribute name.
	 */
	if ( ( $end - 5 ) !== strcspn( $html_attribute_name, "=/> \t\f\r\n", 5 ) ) {
		return null;
	}

	/**
	 * > For each name in list, for each U+002D HYPHEN-MINUS character (-)
	 * > in the name that is followed by an ASCII lower alpha, remove the
	 * > U+002D HYPHEN-MINUS character (-) and replace the character that
	 * > followed it by the same character converted to ASCII uppercase.
	 *
	 * @see https://html.spec.whatwg.org/#concept-domstringmap-pairs
	 */
	$custom_name = '';
	$at          = 5;
	$was_at      = $at;

	while ( $at < $end ) {
		$next_dash_at = strpos( $html_attribute_name, '-', $at );
		if ( false === $next_dash_at || $next_dash_at === $end - 1 ) {
			break;
		}

		// Transform `-a` to `A`, for example.
		$c = $html_attribute_name[ $next_dash_at + 1 ];
		if ( ( $c >= 'A' && $c <= 'Z' ) || ( $c >= 'a' && $c <= 'z' ) ) {
			$prefix       = substr( $html_attribute_name, $was_at, $next_dash_at - $was_at );
			$custom_name .= strtolower( $prefix );
			$custom_name .= strtoupper( $c );
			$at           = $next_dash_at + 2;
			$was_at       = $at;
			continue;
		}

		$at = $next_dash_at + 1;
	}

	// If nothing has been added it means there are no dash-letter pairs; return the name as-is.
	return '' === $custom_name
		? strtolower( substr( $html_attribute_name, 5 ) )
		: ( $custom_name . strtolower( substr( $html_attribute_name, $was_at ) ) );
}

/**
 * Returns a corresponding HTML attribute name for the given name,
 * if that name were found in a JS element’s `dataset` property.
 *
 * Example:
 *
 *     'data-post-id'        === wp_html_custom_data_attribute_name( 'postId' );
 *     'data--before'        === wp_html_custom_data_attribute_name( 'Before' );
 *     'data---one---two---' === wp_html_custom_data_attribute_name( '-One--Two---' );
 *
 *     // Not every attribute name will be interpreted as a custom data attribute.
 *     null === wp_html_custom_data_attribute_name( '/not-an-attribute/' );
 *     null === wp_html_custom_data_attribute_name( 'no spaces' );
 *
 *     // Some very surprising names will; for example, a property whose name is the empty string.
 *     'data-' === wp_html_custom_data_attribute_name( '' );
 *
 * @since 6.9.0
 *
 * @see https://html.spec.whatwg.org/#concept-domstringmap-pairs
 * @see \wp_js_dataset_name()
 *
 * @param string $js_dataset_name Name of JS `dataset` property to transform.
 * @return string|null Corresponding name of an HTML custom data attribute for the given dataset name,
 *                     if possible to represent in HTML, otherwise `null`.
 */
function wp_html_custom_data_attribute_name( string $js_dataset_name ): ?string {
	$end = strlen( $js_dataset_name );
	if ( 0 === $end ) {
		return 'data-';
	}

	/*
	 * If it contains characters which would end the attribute name parsing then
	 * something it’s not possible to represent this in HTML.
	 */
	if ( strcspn( $js_dataset_name, "=/> \t\f\r\n" ) !== $end ) {
		return null;
	}

	$html_name = 'data-';
	$at        = 0;
	$was_at    = $at;

	while ( $at < $end ) {
		$next_upper_after = strcspn( $js_dataset_name, 'ABCDEFGHIJKLMNOPQRSTUVWXYZ', $at );
		$next_upper_at    = $at + $next_upper_after;
		if ( $next_upper_at >= $end ) {
			break;
		}

		$prefix     = substr( $js_dataset_name, $was_at, $next_upper_at - $was_at );
		$html_name .= strtolower( $prefix );
		$html_name .= '-' . strtolower( $js_dataset_name[ $next_upper_at ] );
		$at         = $next_upper_at + 1;
		$was_at     = $at;
	}

	if ( $was_at < $end ) {
		$html_name .= strtolower( substr( $js_dataset_name, $was_at ) );
	}

	return $html_name;
}