How to create widget shortcode

function widget($atts) {

global $wp_widget_factory;

extract(shortcode_atts(array(
    'widget_name' => FALSE
), $atts));

$widget_name = wp_specialchars($widget_name);

if (!is_a($wp_widget_factory->widgets[$widget_name], 'WP_Widget')):
    $wp_class = 'WP_Widget_'.ucwords(strtolower($class));

    if (!is_a($wp_widget_factory->widgets[$wp_class], 'WP_Widget')):
        return '<p>'.sprintf(__("%s: Widget class not found. Make sure this widget exists and the class name is correct"),'<strong>'.$class.'</strong>').'</p>';
    else:
        $class = $wp_class;
    endif;
endif;

ob_start();
the_widget($widget_name, $instance, array('widget_id'=>'arbitrary-instance-'.$id,
    'before_widget' => '',
    'after_widget' => '',
    'before_title' => '',
    'after_title' => ''
));
$output = ob_get_contents();
ob_end_clean();
return $output; 
}
add_shortcode('widget','widget');

[widget widget_name="Your_Custom_Widget"]