For WPML compatible

For compatibility with WPML, change your private function format_from_url:
Instead of home_url () use

$mass_home_url = explode("/", home_url());
$cur_url = $mass_home_url[0]."//".$mass_home_url[2];

Your private function should look like this:

private function format_from_url( $string ) {
$mass_home_url = explode("/", home_url());
$cur_url = $mass_home_url[0]."//".$mass_home_url[2];

$complete = $cur_url . '/' . $string;
list($uprotocol,$uempty,$uhost,$from) = explode( '/', $complete, 4);
$from = '/' . $from;
return strtolower( rtrim( $from, '/') );
}