class DrupalTranslator

Context.php in drupal/core/lib/Drupal/Core/Plugin/Context/Context.php

Contains \Drupal\Core\Plugin\Context\Context.

TypedDataManager.php in drupal/core/lib/Drupal/Core/TypedData/TypedDataManager.php

Contains \Drupal\Core\TypedData\TypedDataManager.

class DrupalTranslator implements TranslatorInterface {

  /**
   * The locale used for translating.
   *
   * @var string
   */
  protected $locale;

  /**
   * Implements \Symfony\Component\Translation\TranslatorInterface::trans().
   */
  public function trans($id, array $parameters = array(), $domain = NULL, $locale = NULL) {
    return t($id, $this
      ->processParameters($parameters), $this
      ->getOptions($domain, $locale));
  }

  /**
   * Implements \Symfony\Component\Translation\TranslatorInterface::transChoice().
   */
  public function transChoice($id, $number, array $parameters = array(), $domain = NULL, $locale = NULL) {

    // Violation messages can separated singular and plural versions by "|".
    $ids = explode('|', $id);
    if (!isset($ids[1])) {
      throw new \InvalidArgumentException(sprintf('The message "%s" cannot be pluralized, because it is missing a plural (e.g. "There is one apple|There are @count apples").', $id));
    }
    return format_plural($number, $ids[0], $ids[1], $this
      ->processParameters($parameters), $this
      ->getOptions($domain, $locale));
  }

  /**
   * Implements \Symfony\Component\Translation\TranslatorInterface::setLocale().
   */
  public function setLocale($locale) {
    $this->locale = $locale;
  }

  /**
   * Implements \Symfony\Component\Translation\TranslatorInterface::getLocale().
   */
  public function getLocale() {
    return $this->locale ? $this->locale : language(Language::TYPE_INTERFACE)->langcode;
  }

  /**
   * Processes the parameters array for use with t().
   */
  protected function processParameters(array $parameters) {
    $return = array();
    foreach ($parameters as $key => $value) {
      if (is_object($value)) {

        // t() does not work will objects being passed as replacement strings.
      }
      elseif (strpos($key, '{{ ') === 0 && strrpos($key, ' }}') == strlen($key) - 3) {

        // Transform it into a Drupal pattern using the format %name.
        $key = '%' . substr($key, 3, strlen($key) - 6);
        $return[$key] = $value;
      }
      else {
        $return[$key] = $value;
      }
    }
    return $return;
  }

  /**
   * Returns options suitable for use with t().
   */
  protected function getOptions($domain = NULL, $locale = NULL) {

    // We do not support domains, so we ignore this parameter.
    // If locale is left NULL, t() will default to the interface language.
    $locale = isset($locale) ? $locale : $this->locale;
    return array(
      'langcode' => $locale,
    );
  }

}