Regular expression to match balanced parentheses

Question

I need a regular expression to select all the text between two outer brackets.

Example: some text(text here(possible text)text(possible text(more text)))end text

Result: (text here(possible text)text(possible text(more text)))

Answer 1

I want to add this answer for quickreference. Feel free to update.

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.NET Regex using balancing groups.

\((?>\((?<c>)|[^()]+|\)(?<-c>))*(?(c)(?!))\) 

Where c is used as the depth counter.

Demo at Regexstorm.com

• Stack Overflow: Using RegEx to balance match parenthesis
• Wes' Puzzling Blog: Matching Balanced Constructs with .NET Regular Expressions
• Greg Reinacker's Weblog: Nested Constructs in Regular Expressions

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PCRE using a recursive pattern.

\((?:[^)(]+|(?R))*+\) 

Demo at regex101; Or without alternation:

\((?:[^)(]*(?R)?)*+\) 

Demo at regex101; Or unrolled for performance:

\([^)(]*+(?:(?R)[^)(]*)*+\) 

Demo at regex101; The pattern is pasted at (?R) which represents (?0).

Perl, PHP, Notepad++, R: perl=TRUE, Python: Regex package with (?V1) for Perl behaviour.

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Ruby using subexpression calls.

With Ruby 2.0 \g<0> can be used to call full pattern.

\((?>[^)(]+|\g<0>)*\) 

Demo at Rubular; Ruby 1.9 only supports capturing group recursion:

(\((?>[^)(]+|\g<1>)*\)) 

Demo at Rubular  (atomic grouping since Ruby 1.9.3)

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JavaScript  API :: XRegExp.matchRecursive

XRegExp.matchRecursive(str, '\\(', '\\)', 'g'); 

JS, Java and other regex flavors without recursion up to 2 levels of nesting:

\((?:[^)(]+|\((?:[^)(]+|\([^)(]*\))*\))*\) 

Demo at regex101. Deeper nesting needs to be added to pattern.
To fail faster on unbalanced parenthesis drop the + quantifier.

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Java: An interesting idea using forward references by @jaytea.

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_{Reference - What does this regex mean?}

• rexegg.com - Recursive Regular Expressions
• Regular-Expressions.info - Regular Expression Recursion