Решение на упр.08 задача 1 от Пламен Колев
Код
use std::rc::Rc;
struct List<T> {
head: Link<T>,
}
type Link<T> = Option<Rc<Node<T>>>;
struct Node<T> {
elem: T,
next: Link<T>,
}
struct Iter<'a, T> {
next: Option<&'a Node<T>>,
}
impl<'a, T> Iterator for Iter<'a, T> {
type Item = &'a T;
fn next(&mut self) -> Option<Self::Item> {
self.next.map(|n| { self.next = n.next.as_deref();
&n.elem
})
}
}
impl<T> List<T> {
fn new() -> Self {
List{head: None}
}
fn head(&self) -> Option<&T> {
self.head.as_ref().map(|n| &n.elem)
}
fn tail(&self) -> List<T> {
List { head: self.head.as_ref().and_then(|n| n.next.clone())}
}
fn prepend(&self, value: T) -> List<T> {
List {
head: Some(Rc::new(Node {
elem: value,
next: self.head.clone(),
})),
}
}
fn iter(&self) -> Iter<'_, T> {
Iter {next: self.head.as_deref()}
}
}
impl<T> List<T> {
fn drop2(mut self){
let mut head = self.head.take();
while let Some(node) = head {
head = Rc::try_unwrap(node).ok().and_then(|n| n.next);
}
}
}
fn main() {
let mut list = List::new();
for i in 0..1_000_000 {
list = list.prepend(i);
}
list.drop2();
}