`{3,}|~{3,})[^\n]*\n.*?(?:^ {0,3}\k[`~]*[ \t]*$|\z)/ms'; /** * Run a transformation over the markdown outside its fenced code blocks. * * @param callable(string): string $callback */ public static function outside(string $content, callable $callback): string { $fences = []; $masked = preg_replace_callback(self::PATTERN, function (array $matches) use (&$fences): string { $placeholder = "\0".count($fences)."\0"; $fences[$placeholder] = $matches[0]; return $placeholder; }, $content); if ($masked === null) { return $content; } return str_replace(array_keys($fences), array_values($fences), $callback($masked)); } }