Drupal Hook to add token functionality to default values of fields

token_functionality_in_fields

 /**
 * Implements hook_field_widget_form_alter().
 */
function MODULENAME_hook_field_widget_form_alter(&$element, &$form_state, $context) {
 
  // Prevent replace tokens on field admin ui form.
  if (!is_null($element['#entity'])) {
    // Determine the $user. If entity has uid, try to load. If can't, use the
    // global $user.
  if (isset($element['#entity']->uid)) {
      if (!$user = user_load($element['#entity']->uid)) {
        global $user;
      }
    }else{
     global $user;
    }

    // Build data for token replacement.
    $data = array(
      $element['#entity_type'] => $element['#entity'],
      'user' => $user,
    );
    // Eg. the body field, the default value is stored in
    // $element['#default_value']
     
    if (isset($element['#default_value']) && (!is_array($element['#default_value']))) {
      $element['#default_value'] = token_replace($element['#default_value'], $data);
    }
    // Eg. the link field, the default value is stored in
    // $element['#default_value']['url']
    else if (isset($element['#default_value']) && (is_array($element['#default_value']))) {
      foreach ($element['#default_value'] as $key => $value) {
        if (is_string($value)) {
          $element['#default_value'][$key] = token_replace($value, $data);
        }
      }
    }
    // Eg. the text field, the default value is stored in
    // $element['value']['#default_value']
    else if (isset($element['value'])) {
      if (isset($element['value']['#default_value']) && !is_array($element['value']['#default_value'])) {
        $element['value']['#default_value'] = token_replace($element['value']['#default_value'], $data);
      }
    }
  }
}