1 locale.module locale($string = NULL, $context = NULL, $langcode = NULL)

Provides interface translation services.

This function is called from t() to translate a string if needed.


$string: A string to look up translation for. If omitted, all the cached strings will be returned in all languages already used on the page.

$context: The context of this string.

$langcode: Language code to use for the lookup.


core/modules/locale/locale.module, line 530
Add language handling functionality and enables the translation of the user interface to languages other than English.


function locale($string = NULL, $context = NULL, $langcode = NULL) {
  global $language;

  // Use the advanced backdrop_static() pattern, since this is called very often.
  static $backdrop_static_fast;
  if (!isset($backdrop_static_fast)) {
    $backdrop_static_fast['locale'] = &backdrop_static(__FUNCTION__);
  $locale_t = &$backdrop_static_fast['locale'];

  if (!isset($string)) {
    // Return all cached strings if no string was specified
    return $locale_t;

  $langcode = isset($langcode) ? $langcode : $language->langcode;

  // Store database cached translations in a static variable. Only build the
  // cache after $language has been set to avoid an unnecessary cache
  // rebuild.
  if (!isset($locale_t[$langcode]) && isset($language)) {
    $locale_t[$langcode] = array();
    // 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 (settings_get('locale_cache_strings', 1) == 1) {
      if ($cache = cache()->get('locale:' . $langcode)) {
        $locale_t[$langcode] = $cache->data;
      elseif (lock_acquire('locale_cache_' . $langcode)) {
        // Refresh database stored cache of translations for given language.
        // We only store short strings used in current version, to improve
        // performance and consume less memory.
        try {
          $result = db_query("SELECT s.source, s.context, t.translation, t.language FROM {locales_source} s LEFT JOIN {locales_target} t ON s.lid = t.lid AND t.language = :language WHERE s.version = :version AND LENGTH(s.source) < :length", array(
            ':language' => $langcode,
            ':version' => BACKDROP_VERSION,
            ':length' => config_get('locale.settings', 'cache_length'),
          foreach ($result as $data) {
            $locale_t[$langcode][$data->context][$data->source] = (empty($data->translation) ? TRUE : $data->translation);
          cache()->set('locale:' . $langcode, $locale_t[$langcode]);
          lock_release('locale_cache_' . $langcode);
        catch (PDOException $e) {
          // Throw exception for any problem except for missing database tables.
          if ($e->getCode() !== '42S02') {
            throw $e;
          return $string;

  // If we have the translation cached, skip checking the database
  if (!isset($locale_t[$langcode][$context][$string])) {
    // We do not have this translation cached, so get it from the DB.
    try {
      $translation = db_query("SELECT s.lid, t.translation, s.version FROM {locales_source} s LEFT JOIN {locales_target} t ON s.lid = t.lid AND t.language = :language WHERE s.source = :source AND s.context = :context", array(
        ':language' => $langcode,
        ':source' => $string,
        ':context' => (string) $context,
    // In the event the table does not exist (such as when uninstalling the
    // module), just return the untranslated string.
    catch (PDOException $e) {
      return $string;

    if ($translation) {
      // We have the source string at least.
      // Cache translation string or TRUE if no translation exists.
      $locale_t[$langcode][$context][$string] = (empty($translation->translation) ? TRUE : $translation->translation);

      if ($translation->version != BACKDROP_VERSION) {
        // This is the first use of this string under current Backdrop version. Save version
        // and clear cache, to include the string into caching next time. Saved version is
        // also a string-history information for later pruning of the tables.
          ->fields(array('version' => BACKDROP_VERSION))
          ->condition('lid', $translation->lid)
    else {
      // We don't have the source string, cache this as untranslated.
          'location' => request_uri(),
          'version' => BACKDROP_VERSION,
          'source' => $string,
          'context' => (string) $context,
      $locale_t[$langcode][$context][$string] = TRUE;
      // Clear locale cache so this string can be added in a later request.

  return ($locale_t[$langcode][$context][$string] === TRUE ? $string : $locale_t[$langcode][$context][$string]);