detecting urls

detect url regex.php

<?php

$letnum = '\p{L}\p{Mn}\p{Mc}\p{Nd}';
$sym = '+&@#/%=~_|$';
$pnct = '?!:,.-';
$c1 = "[$letnum$sym$pnct]";
$c2 = "[$letnum$sym]";
// then the regex pattern is, so to speak:
// \b(?: https?:// | www\. ) (?: \($c1*\) | $c1 )* (?: \($c1*\) | $c2 )
// with xui options.
// the resulting pattern is something like
'{
  \b(?: https?:// | www\. ) 
  (?: \([\p{L}\p{Mn}\p{Mc}\p{Nd}+&@#/%=~_|$?!:,.-]*\) | [\p{L}\p{Mn}\p{Mc}\p{Nd}+&@#/%=~_|$?!:,.-] )* 
  (?: \([\p{L}\p{Mn}\p{Mc}\p{Nd}+&@#/%=~_|$?!:,.-]*\) | [\p{L}\p{Mn}\p{Mc}\p{Nd}+&@#/%=~_|$] ) 
}xui'