title: create regex to match format of 00:00:00 for duration (not time)
body: <p>Hi i'm using laravel and I want to validate create a regex which will allow a specific format for duration (not time as this can exceed a 24 hr format). so for example 124hrs 30 mins and 24 secs would be represented as follows 124:30:24. But the first value can be over 1 character and a number, the second value needs be a colon, the third value needs to be 2 characters and a number, the fourth value needs to be a colon and the fifth value needs to be 2 characters and a numbers.</p>
  
  <p>Any ideas how I can create an regex that will achieve this to insert into the following array?</p>
  
  <pre><code>$rules = array(
    'duration'          =&gt; 'required|regex:/^(?=.*[a-z])(?=.*[A-Z])(?=.*\d).+$/'
  );
  </code></pre>
  
  <p>invalid examples:</p>
  
  <pre><code>alphacharacters e.g. qwerty
  0:0:0
  0:
  0
  1
  30:211:211
  30:2111:2111
  a:d:d
  asd
  </code></pre>
  
  <p>valid examples:</p>
  
  <pre><code>01:00:00
  1:00:00
  30:21:21
  330:21:21
  1330:21:21
  11330:21:21
  basically any amount of hours.
  </code></pre>