php语法如何快速实现排序的非递归算法

function quick_sort(&$arr) {
  $stack = new SplStack(); // 使用SplStack实现栈
  $stack->push(count($arr) - 1); // 将整个数组的下标压入栈
  $stack->push(0);
  while (!$stack->isEmpty()) {
    $left = $stack->pop();
    $right = $stack->pop();
    $pivotIndex = partition($arr, $left, $right);
    if ($left < $pivotIndex - 1) {
      $stack->push($pivotIndex - 1);
      $stack->push($left);
    }
    if ($pivotIndex + 1 < $right) {
      $stack->push($right);
      $stack->push($pivotIndex + 1);
    }
  }
}