class DurationIso8601

class DurationIso8601 extends StringData implements DurationInterface {
  
  /**
   * {@inheritdoc}
   */
  public function getDuration() {
    if ($this->value) {
      // @todo Add support for negative intervals on top of the DateInterval
      // constructor.
      return new \DateInterval($this->value);
    }
  }
  
  /**
   * {@inheritdoc}
   */
  public function getDurationAsIso8601Abnf() : string {
    return $this->value;
  }
  
  /**
   * {@inheritdoc}
   */
  public function getCastedValue() {
    return parent::getCastedValue();
  }
  
  /**
   * {@inheritdoc}
   */
  public function setDuration(\DateInterval $duration, $notify = TRUE) {
    // Generate an ISO 8601 formatted string as supported by
    // DateInterval::__construct() and setValue().
    $this->value = $duration->format('%rP%yY%mM%dDT%hH%mM%sS');
    // Notify the parent of any changes.
    if ($notify && isset($this->parent)) {
      $this->parent
        ->onChange($this->name);
    }
  }

}