PCRE (recursive) pattern that matches a string containing a correctly parenthesized substring. Why d

Posted by Anton N. Petrov on Stack Overflow See other posts from Stack Overflow or by Anton N. Petrov
Published on 2010-06-04T11:26:16Z Indexed on 2010/06/05 23:12 UTC
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regex

|

perl

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pcre

Well, there are other ways (hmmm... or rather working ways) to do it, but the question is why does this one fail?

/
\A              # start of the string
(               # group 1
(?:             # group 2
[^()]*          # something other than parentheses (greedy)
|               # or
\( (?1) \)      # parenthesized group 1
)               # -group 2
+               # at least once (greedy)
)               # -group 1
\Z              # end of the string
/x

Fails to match a string with nested parentheses: "(())"

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