$re = '/^SW(TS|L|M)-(\d+)([:,] )([wW][iI][pP])?(?(4)[ \w]{3,}|(?!([wW][iI][pP]))[ \w]{3,}).*$/m';
$str = 'SWL-101
just did it
SWL-101: wip something is about to be done
SWL-102: wip
SWTS-103, we did something cool
SWM-104, i am groot!
';
preg_match_all($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