Oct. 27, 2015
2:26 a.m.
On Tue, Oct 27, 2015 at 8:44 AM, Ben Finney <ben+python@benfinney.id.au> wrote:
You seem to be seeking something else: a pattern that matches all valid regex patterns, *and* will never match any string that is not a valid regex pattern. The latter is rather more difficult.
"Rather more difficult" may be an understatement. A regex can contain grouping parentheses which can arbitrarily nest, and matching that with a regex is, AIUI, fundamentally impossible. So I don't think it's possible to have a regex that validates a regex. Fortunately, it's easy to write a function that validates a regex. def is_regex(s): try: re.compile(s) except re.error: return False return True ChrisA