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run code in 150+ php & hhvm versions
Bugs & Features
<?php $pattern="/\(((?>[^()]+)|(?R))*\)/"; //$str="(def a (x) (+ 1 x))(print (a 1))"; $str="(aaa)"; preg_match_all($pattern,$str,$out); var_dump($out);
Output for 4.3.0 - 5.6.28, hhvm-3.10.0 - 3.12.0, 7.0.0 - 7.1.0
array(2) { [0]=> array(1) { [0]=> string(5) "(aaa)" } [1]=> array(1) { [0]=> string(3) "aaa" } }