function drupal_lookup_path

Given an alias, return its Drupal system URL if one exists. Given a Drupal system URL return one of its aliases if such a one exists. Otherwise, return FALSE.

Parameters

$action: One of the following values:

• wipe: delete the alias cache.
• alias: return an alias for a given Drupal system path (if one exists).
• source: return the Drupal system URL for a path alias (if one exists).

$path: The path to investigate for corresponding aliases or system URLs.

Return value

Either a Drupal system path, an aliased path, or FALSE if no path was found.

File

includes/path.inc, line 41

Functions to handle paths in Drupal, including path aliasing.

Code

function drupal_lookup_path($action, $path = '') {

  // $map keys are Drupal paths and the values are the corresponding aliases
  static $map = array(), $no_src = array();
  static $count;

  // Use $count to avoid looking up paths in subsequent calls if there simply are no aliases
  if (!isset($count)) {
    $count = db_result(db_query('SELECT COUNT(pid) FROM {url_alias}'));
  }
  if ($action == 'wipe') {
    $map = array();
    $no_src = array();
  }
  elseif ($count > 0 && $path != '') {
    if ($action == 'alias') {
      if (isset($map[$path])) {
        return $map[$path];
      }
      $alias = db_result(db_query("SELECT dst FROM {url_alias} WHERE src = '%s'", $path));
      $map[$path] = $alias;
      return $alias;
    }
    elseif ($action == 'source' && !isset($no_src[$path])) {

      // Look for the value $path within the cached $map
      if (!($src = array_search($path, $map))) {
        if ($src = db_result(db_query("SELECT src FROM {url_alias} WHERE dst = '%s'", $path))) {
          $map[$src] = $path;
        }
        else {

          // We can't record anything into $map because we do not have a valid
          // index and there is no need because we have not learned anything
          // about any Drupal path. Thus cache to $no_src.
          $no_src[$path] = TRUE;
        }
      }
      return $src;
    }
  }
  return FALSE;
}