date_recur-8.x-2.2/src/Plugin/Validation/Constraint/DateRecurRruleConstraintValidator.php

<?php

declare(strict_types=1);

namespace Drupal\date_recur\Plugin\Validation\Constraint;

use Drupal\date_recur\DateRecurHelper;
use Drupal\date_recur\Plugin\Field\FieldType\DateRecurItem;
use Symfony\Component\Validator\Constraint;
use Symfony\Component\Validator\ConstraintValidator;

/**
 * Validates the DateRecurRruleConstraint constraint.
 */
class DateRecurRruleConstraintValidator extends ConstraintValidator {

  /**
   * {@inheritdoc}
   */
  public function validate($value, Constraint $constraint): void {
    assert($value instanceof DateRecurItem);
    assert($constraint instanceof DateRecurRruleConstraint);

    // Validator do not apply to field values without RRULE.
    if ($value->rrule === NULL || $value->rrule === '') {
      return;
    }

    try {
      // Use a fake start time as there may be an empty or invalid start date.
      DateRecurHelper::create($value->rrule, new \DateTime());
    }
    catch (\Exception) {
      $this->context->addViolation($constraint->invalidRrule);
    }
  }

}