$re = '/(012(?:3(?:4(?:5(?:6(?:7(?:89?)?)?)?)?)?)?|123(?:4(?:5(?:6(?:7(?:89?)?)?)?)?)?|234(?:5(?:6(?:7(?:89?)?)?)?)?|345(?:6(?:7(?:89?)?)?)?|456(?:7(?:89?)?)?|567(?:89?)?|6789?|789)/m';
$str = '23412167894125012';
preg_match_all($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