$re = '/{@\w+\(.*?\)}(?![^|])(*SKIP)(*F)|\|/';
$str = '123|@rand(тест {@rand(номер 1234|номер 4321)}|строка||
123|1231|41245
hi|{@rand(1|2)}|bye';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php