问题描述
我是 rust 的新手,并试图在数组中维护 2 个链表,我的代码如下:
#[derive(copy,Clone)]
struct Node {
next: i32,prev: i32,val: i32
}
impl Node {
pub fn new()->Self{
Self{
next: 0,val: 0,prev: 0
}
}
pub fn get_prev(&self) -> i32{
self.prev
}
pub fn get_next(&self) -> i32{
self.next
}
pub fn set_prev(& mut self,idx: i32){
self.prev = idx;
}
pub fn set_next(& mut self,idx: i32){
self.next = idx;
}
pub fn get_val(&self)->i32{
self.val
}
pub fn set_val(& mut self,v: i32){
self.val = v;
}
}
struct MyVec{
red_start: i32,black_start: i32,data: [Node; 48]
}
impl MyVec{
pub fn new()->Self{
let mut ans = Self{
red_start : -1,black_start: 0,data: [Node::new(); 48]
};
let len = ans.data.len();
for i in 0..ans.data.len(){
let n: & mut Node = & mut ans.data[i];
n.set_prev(((i + len-1) % len) as i32);
n.set_next(((i+1) % len) as i32);
}
ans
}
pub fn move_black_to_red(& mut self,idx: i32){
let n: & mut Node = & mut self.data[idx as usize];
let prev: & mut Node = & mut self.data[n.get_prev() as usize];
let next: & mut Node = & mut self.data[n.get_next() as usize];
prev.set_next(n.get_next());
next.set_prev(n.get_prev());
//other stuff...
}
}
难点在move_black_to_red fucntion,我需要维护这个列表,所以我需要同时获取3个mut引用并更新它们。但是,最多只能从 self 借用 1 mut,那我该怎么办?
解决方法
Rust 不允许同时对同一个变量进行多个可变引用。解决此问题的最简单方法是交错借用,并且不可变地借用 n
,因为您永远不会改变它:
pub fn move_black_to_red(& mut self,idx: i32){
let n: Node = self.data[idx as usize];
let prev: & mut Node = & mut self.data[n.get_prev() as usize];
prev.set_next(n.get_next());
let next: & mut Node = & mut self.data[n.get_next() as usize];
next.set_prev(n.get_prev());
//other stuff...
}