Решение на упр.08 задача 1 от Венислав Трендафилов
Към профила на Венислав Трендафилов
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>,
}
pub struct Iter<'a, T> {
next: Option<&'a Node<T>>,
}
impl<T> List<T> {
fn new() -> Self {
List { head: None }
}
fn head(&self) -> Option<&T> {
self.head.as_ref().map(|node| &node.elem)
}
fn tail(&self) -> List<T> {
let next_link = match self.head.as_ref() {
Some(node) => node.next.clone(),
None => None,
};
List { head: next_link }
}
fn prepend(&self, value: T) -> List<T> {
let new_node = Rc::new(Node {
elem: value,
next: self.head.clone(),
});
List { head: Some(new_node) }
}
fn iter(&self) -> Iter<'_, T> {
Iter {
next: self.head.as_deref(),
}
}
}
impl<'a, T> Iterator for Iter<'a, T> {
type Item = &'a T;
fn next(&mut self) -> Option<Self::Item> {
match self.next {
Some(node) => {
self.next = node.next.as_ref().map(|next_rc| next_rc.as_ref());
Some(&node.elem)
}
None => None,
}
}
}
impl<T> Drop for List<T> {
fn drop(&mut self) {
let mut link = self.head.take();
while let Some(rc_node) = link {
if let Ok(mut node) = Rc::try_unwrap(rc_node) {
link = node.next.take();
} else {
break;
}
}
}
}