class LocaleLookup

LocaleTranslation.php in drupal/core/modules/locale/lib/Drupal/locale/LocaleTranslation.php

Contains \Drupal\Core\Language\LocaleTranslation.

class LocaleLookup extends CacheArray implements DestructableInterface {

  /**
   * A language code.
   *
   * @var string
   */
  protected $langcode;

  /**
   * The msgctxt context.
   *
   * @var string
   */
  protected $context;

  /**
   * The locale storage.
   *
   * @var \Drupal\locale\StringStorageInterface
   */
  protected $stringStorage;

  /**
   * Constructs a LocaleCache object.
   */
  public function __construct($langcode, $context, $string_storage) {
    $this->langcode = $langcode;
    $this->context = (string) $context;
    $this->stringStorage = $string_storage;

    // Add the current user's role IDs to the cache key, this ensures that, for
    // example, strings for admin menu items and settings forms are not cached
    // for anonymous users.
    $rids = isset($GLOBALS['user']) ? implode(':', array_keys($GLOBALS['user']->roles)) : '0';
    parent::__construct("locale:{$langcode}:{$context}:{$rids}", 'cache', array(
      'locale' => TRUE,
    ));
  }

  /**
   * {@inheritdoc}
   */
  protected function resolveCacheMiss($offset) {
    $translation = $this->stringStorage
      ->findTranslation(array(
      'language' => $this->langcode,
      'source' => $offset,
      'context' => $this->context,
    ));
    if ($translation) {
      $value = !empty($translation->translation) ? $translation->translation : TRUE;
    }
    else {

      // We don't have the source string, update the {locales_source} table to
      // indicate the string is not translated.
      $this->stringStorage
        ->createString(array(
        'source' => $offset,
        'context' => $this->context,
        'version' => VERSION,
      ))
        ->addLocation('path', request_uri())
        ->save();
      $value = TRUE;
    }
    $this->storage[$offset] = $value;

    // Disabling the usage of string caching allows a module to watch for
    // the exact list of strings used on a page. From a performance
    // perspective that is a really bad idea, so we have no user
    // interface for this. Be careful when turning this option off!
    if (config('locale.settings')
      ->get('cache_strings')) {
      $this
        ->persist($offset);
    }
    return $value;
  }

  /**
   * {@inheritdoc}
   */
  public function destruct() {
    parent::__destruct();
  }

  /**
   * {@inheritdoc}
   */
  public function __destruct() {

    // Do nothing to avoid segmentation faults. This can be restored after the
    // cache collector from http://drupal.org/node/1786490 is used.
  }

}