MODx - Build closure table array

<?php

function buildHierarchy(&$results, $parent = 0, $level = 0)
{
  global $modx;
  $children = array_values($modx->getChildIds($parent, 1));
  $level = $level + 1;
  foreach($children as $child)
  {
    $descendents = array_values($modx->getChildIds($child, 100));
    array_unshift($descendents, $child);
    $results[$child] = array(
                        'id'     => $child,
                        'descendents' => $descendents,
                        'level'  => $level,
                       );
    buildHierarchy($results, $child, $level);
  }
}

function buildClosureTable($results)
{
  $closure_array = array();
  foreach($results as $result)
  {
    foreach($result['descendents'] as $child)
    {
      $closure_array[] = array(
        'ancestor' => $result['id'],
        'descendent' => $child,
        'level' => $results[$child]['level'],
      );
    }
  }
  
  return $closure_array;
}

$root = 0;
$descendents = array_values($modx->getChildIds($root, 100));
array_unshift($descendents, $root);

$results = array(0 => array(
                          'id' => 0,
                          'descendents' => $descendents,
                          'level' => 0,
                      )
                );
buildHierarchy($results);
$closure_array = buildClosureTable($results);



$table_tpl = '<table cellpadding="5"><tr><th>Ancestor</th><th>Descendent</th><th>Level</th></tr>%s</table>';
$rows_tpl = '<tr><td>%s</td><td>%s</td><td>%s</td></tr>';
$rows = '';
foreach($closure_array as $row)
{
  $rows .= sprintf($rows_tpl, $row['ancestor'], $row['descendent'], $row['level']);
}

echo sprintf($table_tpl, $rows);