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<?php $str = '(a,b),a,b,c,(a,f)'; $str = preg_replace_callback('`("|\').*?\1`', function ($matches) { return preg_replace('`(?<!\\\)[()]`', '\\\;', $matches[0]); }, $str); echo $str;

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47.38 ms | 402 KiB | 5 Q