Regex Tester & Validator

With the extended (x) flag on, the Russian comments are ignored. This PCRE pattern matches regular expression literals as written in PHP: a pattern enclosed in delimiters — punctuation like /, #, ~ or paired brackets <>, (), [], {} — with recursion (?R) to handle nested regex literals, closed by the matching delimiter, and followed by optional PHP preg modifiers (mixXsuUAJ). It's useful for extracting or highlighting regex literals embedded in source code.