PHP: codeigniter simulate $_GET parameter

gistfile1

<?php 

$url = parse_url( $_SERVER['REQUEST_URI'] );

$get = explode('&', $url['query']);

foreach ($get as $key => $value) {
    list($k, $v) = explode('=', $value);
    $new_get[$k] = $v;
}

var_dump($new_get['callback']);

?>