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run code in 300+ 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);

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