title: Advanced lookarounds in regex
body: <p>Hi I have the this html:</p>
  
  <pre><code>&lt;div class="c-disruption-item c-disruption-item--line"&gt; 
   &lt;h3 class="c-disruption-item__title" id="11e62827-9f9c-48b2-8807-09f6b6ebeec6" name="11e62827-9f9c-48b2-8807-09f6b6ebeec6"&gt; &lt;a&gt;Closure of London Road&lt;/a&gt; &lt;/h3&gt; 
   &lt;ul class="c-disruption__affected-entities"&gt; 
    &lt;li&gt;Affected routes:&lt;/li&gt; 
    &lt;li&gt; &lt;a href="/services/RB/X4#disruptions" class="line-block" style="background-color: #A38142; color:#FFFFFF"&gt; 
      &lt;div class="line-block__contents"&gt;
        X4 
      &lt;/div&gt; &lt;/a&gt; &lt;/li&gt; 
   &lt;/ul&gt;
   &lt;p&gt;The left turn from Wiltshire Road on to London Road will be closed between 10.00pm and 5.00am on the nights of 27/28 and 28/29 April 2020.&lt;br&gt; &lt;br&gt; Lion X4 affected as follows:-&lt;br&gt; &lt;br&gt; Journeys towards Bracknell will be diverted and unable to serve the Seaford Road bus stop. Please use the Three Frogs bus stop instead.&lt;br&gt; &lt;br&gt; Journeys towards Reading are not affected and should follow normal route.&lt;br&gt; &lt;br&gt; We are sorry for the inconvenience caused.&lt;/p&gt; 
  &lt;/div&gt;
  </code></pre>
  
  <p>And I want to select whatever comes before and after the <code>&lt;ul&gt;&lt;/ul&gt;</code> section meaning <strong>not this:</strong></p>
  
  <pre><code>   &lt;ul class="c-disruption__affected-entities"&gt; 
        &lt;li&gt;Affected routes:&lt;/li&gt; 
        &lt;li&gt; &lt;a href="/services/RB/X4#disruptions" class="line-block" style="background-color: #A38142; color:#FFFFFF"&gt; 
          &lt;div class="line-block__contents"&gt;
            X4 
          &lt;/div&gt; &lt;/a&gt; &lt;/li&gt; 
       &lt;/ul&gt;
  </code></pre>
  
  <p>But! <strong>if this section does not exist i want to select all.</strong></p>
  
  <p>I tried this selection <code>([\W\w]+(?=\&lt;ul)|(?&lt;=ul&gt;)[\W\w]+)</code> but it doesn't work if the <code>&lt;ul&gt;&lt;\ul&gt;</code> not exist. 
  The selection have to be regax alone.
  Does somebody have an idea?</p>
  
  <p>thanks</p>