title: regex:pattern validation in Laravel
body: <p>I try validate facebook.com url in Laravel.
  this is my regex:</p>
  
  <pre><code>    'facebook' =&gt; 'url|regex:((?:(?:http|https):\/\/)?(?:www.)?facebook.com\/(?:(?:\w)*#!\/)?(?:pages\/)?(?:[?\w\-]*\/)?(?:profile.php\?id=(?=\d.*))?([\w\-]*))|nullable',
  </code></pre>
  
  <p>It's work in online regex tests website (<a href="https://regex101.com/" rel="nofollow noreferrer">https://regex101.com/</a>), but in <code>Laravel</code>. I have error</p>
  
  <blockquote>
    <p>"preg_match(): No ending matching delimiter ')' found".</p>
  </blockquote>
  
  <p>what is the problem?</p>