php function to walk an array/object recursively

walk_array.php

/**
 * works for json objects. will replace all
 * keys and values with the result of the
 * closure.
 */
function walk_recursive($obj, $closure) {
  if ( is_object($obj) ) {
    $newObj = new stdClass();
    foreach ($obj as $property => $value) {
      $newProperty = $closure($property);
      $newValue = walk_recursive($value, $closure);
      $newObj->$newProperty = $newValue;
    }
    return $newObj;
  } else if ( is_array($obj) ) {
    $newArray = array();
    foreach ($obj as $key => $value) {
      $key = $closure($key);
      $newArray[$key] = walk_recursive($value, $closure);
    }
    return $newArray;
  } else {
    return $closure($obj);
  }
}