ho provato questo ma non va.

Dove sbaglio?

HOW TO USE:
$codeLighter = new codeLighter();
echo $codeLighter->convert($text_var);
WARNING: the better way to use this script is give an htmlentities($text_var);
so if you haven't converted $text_var you need to do this.
Example:
echo $codeLighter->convert( htmlentities($text_var) );