/**
  * {@inheritdoc}
  */
 public function getPathByAlias($alias, $langcode = NULL)
 {
     // If no language is explicitly specified we default to the current URL
     // language. If we used a language different from the one conveyed by the
     // requested URL, we might end up being unable to check if there is a path
     // alias matching the URL path.
     $langcode = $langcode ?: $this->languageManager->getCurrentLanguage(LanguageInterface::TYPE_URL)->getId();
     // If we already know that there are no paths for this alias simply return.
     if (empty($alias) || !empty($this->noPath[$langcode][$alias])) {
         return $alias;
     }
     // Look for the alias within the cached map.
     if (isset($this->lookupMap[$langcode]) && ($path = array_search($alias, $this->lookupMap[$langcode]))) {
         return $path;
     }
     // Look for path in storage.
     if ($path = $this->storage->lookupPathSource($alias, $langcode)) {
         $this->lookupMap[$langcode][$path] = $alias;
         $this->cacheNeedsWriting = TRUE;
         return $path;
     }
     // We can't record anything into $this->lookupMap because we didn't find any
     // paths for this alias. Thus cache to $this->noPath.
     $this->noPath[$langcode][$alias] = TRUE;
     return $alias;
 }
 protected function lookup($type, $lookup, $langcode = null)
 {
     if (self::SOURCE !== $type) {
         // Exclude all admin paths
         if ($this->excludeAdminPath && path_is_admin($lookup)) {
             return $lookup;
         }
         // Also check for whitelist
         if (false !== $this->whitelist && !isset($this->whitelist[strtok($lookup, '/')])) {
             return $lookup;
         }
     }
     if (!$langcode) {
         $langcode = $GLOBALS['language']->getId();
     }
     // Compute cache key lookup
     if (self::SOURCE === $type) {
         $dest = self::ALIAS;
     } else {
         $type = self::ALIAS;
         $dest = self::SOURCE;
         if ($this->doCache && !$this->isPreloaded) {
             if (empty($this->data[self::ALIAS][$langcode])) {
                 $this->data[self::ALIAS][$langcode] = [];
             }
             $this->data[self::ALIAS][$langcode] += $this->preloadSourceItems($langcode);
             $this->isPreloaded = true;
         }
     }
     if (isset($this->data[$type][$langcode][$lookup])) {
         $found = $this->data[$type][$langcode][$lookup];
         return $found ? $found : $lookup;
     }
     $this->dataIsUpdated = true;
     if (self::SOURCE === $type) {
         $found = $this->storage->lookupPathSource($lookup, $langcode);
     } else {
         $found = $this->storage->lookupPathAlias($lookup, $langcode);
     }
     if ($found) {
         $this->data[$type][$langcode][$lookup] = $found;
         $this->data[$dest][$langcode][$found] = $lookup;
     } else {
         $this->data[$type][$langcode][$lookup] = false;
     }
     return $found ? $found : $lookup;
 }
 public function testTheMockUp()
 {
     // Tests registered aliases
     $this->assertSame('alias-en', $this->aliasStorage->lookupPathAlias('duplicate-langcode', 'en'));
     $this->assertSame('alias-fr', $this->aliasStorage->lookupPathAlias('duplicate-langcode', 'fr'));
     $this->assertSame('alias-und', $this->aliasStorage->lookupPathAlias('duplicate-langcode', LanguageInterface::LANGCODE_NOT_SPECIFIED));
     // Non existing language returns the undefined language alias
     $this->assertSame('alias-und', $this->aliasStorage->lookupPathAlias('duplicate-langcode', 'martian'));
     // More basic tests
     $this->assertSame('duplicate-langcode', $this->aliasStorage->lookupPathSource('alias-fr', 'fr'));
     $this->assertSame('duplicate-langcode', $this->aliasStorage->lookupPathSource('alias-en', 'en'));
     $this->assertFalse($this->aliasStorage->lookupPathSource('alias-fr', LanguageInterface::LANGCODE_NOT_SPECIFIED));
     $this->assertFalse($this->aliasStorage->lookupPathSource('alias-en', LanguageInterface::LANGCODE_NOT_SPECIFIED));
     $this->assertFalse($this->aliasStorage->lookupPathSource('alias-fr', 'en'));
     $this->assertFalse($this->aliasStorage->lookupPathSource('alias-en', 'fr'));
 }