title: RegEx to match any character except strings with surrounding prefixes
body: <p>I'm trying to create a regex which will validate input to match any character but it should exclude input which is surrounded with prefixes (i.e. {#..#}, {@..@} or {$..$}).</p>
  
  <p>Given is the example:</p>
  
  <pre><code>Free text which is fine // should return true
  {#some other text#} // should return false
  Text with numbers 671 // should return true
  {@Hello world@} // should return false
  {$Hello Mars$} // should return false
  {$some text which i do not close // should return true
  </code></pre>
  
  <p>This should be possible with the use of negative look-around, something along the lines of:</p>
  
  <pre><code>^(\?!=(\{@[^.]+@\}))(\?!=(\{$[^.]+$\}))(\?!=(\{#[^.]+#\})).*
  </code></pre>
  
  <p>Any help would be greatly appreciated : )</p>