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run code in 500+ PHP versions simultaneously
<?php $re = '/[\t\n]+(?=[^][]*(?:(\[(?:[^][]++|(?1))*])[^][]*)*])/'; $str = "settings:a [\n a:[\n a:a\n b:b\n ]\n b:[\n a:a\n b:b\n ]\n]\n\nsettings:b [\n a:[\n \n\na:a\n b:b\n ]\n]"; echo preg_replace($re, ' ', $str);
Output for 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.34, 8.2.0 - 8.2.34, 8.3.0 - 8.3.35, 8.4.1 - 8.4.26, 8.5.0 - 8.5.11
settings:a [ a:[ a:a b:b ] b:[ a:a b:b ] ] settings:b [ a:[ a:a b:b ] ]

preferences:
29.32 ms | 1137 KiB | 7 Q