title: Empty groups in regex
body: <p>I use a regexp to test a link :</p>
  
  
  
  <pre class="lang-none prettyprint-override"><code>lolspec:\/\/(spectator\.(na|euw1|eu|kr|oc1|br|la1|la2|ru|tr|pbe1)\.lol\.riotgames\.com:(80|8088)((([?&amp;]region=(NA1|EUW1|EUN1|KR|OC1|BR1|LA1|LA2|RU|TR1|PBE1))|([?&amp;]gameID=([0-9]+))|([?&amp;]encKey=(.+)))){3})
  </code></pre>
  
  <p>to test this link :</p>
  
  <pre class="lang-none prettyprint-override"><code>lolspec://spectator.euw1.lol.riotgames.com:80?region=NA1&amp;gameID=44584&amp;encKey=fghgdsv1134+ianfcuia
  </code></pre>
  
  <p>but some groups are empty (#7, #8, #9)</p>
  
  <p>what should I do ?</p>