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recursive_patterns

🌀 Parse Nested Parentheses with Recursion​

Oniguruma’s recursion support allows matching balanced constructs by recursively referencing the named group. Define a group and use (?&R) within it to handle unlimited nesting.

pattern = /\A\((?:[^()]+|(?<R>\((?&R)\)))*\)\z/
# Example: matches balanced parentheses
tests = ['(a(b)c)', '((x))', 'unbalanced(', '()']
tests.each do |s|
  puts "#{s}: #{!!(s.match(pattern))}"
end