wp_strip_custom_css_from_blocks( string $content ): string

195function wp_strip_custom_css_from_blocks( $content ) {196	if ( ! has_blocks( $content ) ) {197		return $content;198	}199 200	$unslashed = stripslashes( $content );201 202	$parser           = new WP_Block_Parser();203	$parser->document = $unslashed;204	$parser->offset   = 0;205	$end              = strlen( $unslashed );206	$replacements     = array();207 208	while ( $parser->offset < $end ) {209		$next_token = $parser->next_token();210 211		if ( 'no-more-tokens' === $next_token[0] ) {212			break;213		}214 215		list( $token_type, , $attrs, $start_offset, $token_length ) = $next_token;216 217		$parser->offset = $start_offset + $token_length;218 219		if ( 'block-opener' !== $token_type && 'void-block' !== $token_type ) {220			continue;221		}222 223		if ( ! isset( $attrs['style']['css'] ) ) {224			continue;225		}226 227		// Remove css and clean up empty style.228		unset( $attrs['style']['css'] );229		if ( empty( $attrs['style'] ) ) {230			unset( $attrs['style'] );231		}232 233		// Locate the JSON portion within the token.234		$token_string   = substr( $unslashed, $start_offset, $token_length );235		$json_rel_start = strcspn( $token_string, '{' );236		$json_rel_end   = strrpos( $token_string, '}' );237 238		$json_start  = $start_offset + $json_rel_start;239		$json_length = $json_rel_end - $json_rel_start + 1;240 241		// Re-encode attributes. If attrs is now empty, remove JSON and trailing space.242		if ( empty( $attrs ) ) {243			// Remove the trailing space after JSON.244			$replacements[] = array( $json_start, $json_length + 1, '' );245		} else {246			$replacements[] = array( $json_start, $json_length, serialize_block_attributes( $attrs ) );247		}248	}249 250	if ( empty( $replacements ) ) {251		return $content;252	}253 254	// Build the result by splicing replacements into the original string.255	$result = '';256	$was_at = 0;257 258	foreach ( $replacements as $replacement ) {259		list( $offset, $length, $new_json ) = $replacement;260		$result                            .= substr( $unslashed, $was_at, $offset - $was_at ) . $new_json;261		$was_at                             = $offset + $length;262	}263 264	if ( $was_at < $end ) {265		$result .= substr( $unslashed, $was_at );266	}267 268	return addslashes( $result );269}