too-many-lists/advanced-lists/intro

[giscus[bot]]

too-many-lists/advanced-lists/intro

https://course.rs/too-many-lists/advanced-lists/intro.html

[Neutron3529]

使用高级技巧：声明forbid_unsafe之后处处unsafe，以此同时获取性能上的优势，以及避开语言律师

#![forbid(unsafe_code)]
#[inline(always)]
fn extend_mut<'a, T>(input: &'a mut T) -> &'static mut T {
    struct Bounded<'a, 'b: 'static, T>(&'a mut T, [&'b ();0]);
    let mut n:Box<dyn FnMut(&mut T) -> Bounded<'static, '_, T>>=Box::new(|x| Bounded(x, []));
    n(input).0
}
pub struct LinkedListImpl<'a:'static,T>{
    pub data:T,
    pub prev:Option<&'a mut Self>,
    pub next:Option<&'a mut Self>,
}
type LinkedList<T>=LinkedListImpl<'static,T>;
impl<T> LinkedList<T> {
    pub fn new(t:T)->Self{Self{data:t,prev:None,next:None}}
    pub fn insert_next(&mut self, t:&mut Self){
        self.next=Some(extend_mut(t));
        t.prev=Some(extend_mut(self))
    }
    pub fn insert_prev(&mut self, t:&mut Self){
        t.insert_next(self)
    }
// 复杂逻辑我就不写了
}
fn main(){
    let mut a=LinkedList::new(3);
    let mut b=LinkedList::new(4);
    a.insert_next(&mut b);
    println!{"{} {}",a.data, a.next.unwrap().data}
}

[NichtsHsu]

Bug 给你们玩明白了。不过实际这里不用 Box，写 &mut dyn FnMut(&mut T) -> Bounded<'static, '_, T> 也是可以的