AliasManager::getPathByAlias

public AliasManager::getPathByAlias($alias, $langcode = NULL)

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;
    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;
}