title: re2c: syntax error when trying to match string
body: <p>I'm trying to use re2c, but it gives me a syntax error on this regex:</p>
  
  <pre><code>(["'])((\\{2})*|(.*?[^\\](\\{2})*))\1
  </code></pre>
  
  <p>What's wrong with it? This should match a doubly quoted or single quoted string</p>