title: How filter input for Farsi character?
body: <p>I want filter input just for Farsi, i think regular expression with <code>filter_input()</code> is a good idea but 
  i dont know how solve this problem, I've search but i don't find sth like \p{Arabic} for Farsi or Persian character in the other hand it can be possible with <a href="http://www.tamasoft.co.jp/en/general-info/unicode.html" rel="noreferrer">Unicode</a> but i've no idea about its regular expression.</p>