\(the literal ( (4010 / 508 / 2816)
\?the literal ? (6310 / 778 / 3F16)
<?optionally matches the literal < (6010 / 748 / 3C16)
!the literal ! (3310 / 418 / 2116)
=the literal = (6110 / 758 / 3D16)
Group r(?<r>[^()]|\(\g<r>+\))+ +repeats the group contents below at least once:
Negated Character Class[^()] (the literal ( (4010 / 508 / 2816)
)the literal ) (4110 / 518 / 2916)
2nd Alternative\(\g<r>+\) \(the literal ( (4010 / 508 / 2816)
\g<r>+calls group r as a subroutine, repeated at least once
\)the literal ) (4110 / 518 / 2916)
\)the literal ) (4110 / 518 / 2916)
g modifier: global. Finds all matches instead of stopping after the first
m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string