如何借用对RefCell内部本身在Option内的东西的引用？

Question

我正在创建一个带有这样定义的节点的二叉树：

use std::cell::{Ref, RefCell};

pub struct Node<T>
where
    T: Copy + PartialOrd + std::fmt::Display,
{
    data: T,
    left: Option<RefCell<Box<Node<T>>>>,
    right: Option<RefCell<Box<Node<T>>>>,
}

我正在尝试实现一个函数find，该函数应该带有一个根节点和一个密钥，并返回对与给定密钥匹配的节点的引用。我试图递归地实现find，但是在从Option和RefCell中取出左右子树时遇到了麻烦。

fn find<T>(node: Ref<Box<Node<T>>>, data: T) -> Option<Ref<Box<Node<T>>>>
where
    T: Copy + PartialOrd + std::fmt::Display,
{
    if node.data == data {
        return Some(node);
    } else if node.data > data {
        if node.left.is_some() {
            // Error: Cannot move out of borrowed content
            let myref = node.left.unwrap().borrow();
            return find(myref, data);
        } else {
            return None;
        }
    } else {
        if node.right.is_some() {
            // Error: returns a value referencing data owned by the current function
            let myref = node.right.as_ref().unwrap().borrow();
            return find(myref, data);
        } else {
            return None;
        }
    }
}

error[E0507]: cannot move out of borrowed content
  --> src/lib.rs:21:25
   |
21 |             let myref = node.left.unwrap().borrow();
   |                         ^^^^^^^^^ cannot move out of borrowed content

error[E0515]: cannot return value referencing temporary value
  --> src/lib.rs:22:20
   |
21 |             let myref = node.left.unwrap().borrow();
   |                         ------------------ temporary value created here
22 |             return find(myref, data);
   |                    ^^^^^^^^^^^^^^^^^ returns a value referencing data owned by the current function

error[E0515]: cannot return value referencing function parameter `node`
  --> src/lib.rs:30:20
   |
29 |             let myref = node.right.as_ref().unwrap().borrow();
   |                         ---- `node` is borrowed here
30 |             return find(myref, data);
   |                    ^^^^^^^^^^^^^^^^^ returns a value referencing data owned by the current function