title: Emulating a negative lookbehind of unknown width in PCRE
body: <p>I have the <a href="https://regex101.com/r/G8Vrow/7" rel="nofollow noreferrer">following regex</a>:</p>
  
  <pre><code>(?&lt;=:)\s*\w+
  </code></pre>
  
  <p>I want to only extract <code>comp</code> or <code> comp</code> from the string:</p>
  
  <pre><code>savedPosition: comp;
  CURLSCHET.NREC ('qwertyuiop'): noprotect;
  </code></pre>
  
  <p>I want to avoid matching cases like <code>noprotect</code> when there is a <code>(</code> or <code>)</code> anywhere before the required pattern.</p>