sander/rust-workshop-linkedlist
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use Option

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This commit is contained in:
Sander Hautvast 2022-02-14 12:56:00 +01:00
parent 71587e810c
commit eca0964be5
1 changed files with 7 additions and 11 deletions
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18
src/main.rs
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@ -13,11 +13,7 @@ pub struct List<T> {
head: Link<T>, head: Link<T>,
} }
#[derive(Debug)] type Link<T> = Option<Box<Node<T>>>;
enum Link<T> {
Empty,
More(Box<Node<T>>),
}
#[derive(Debug)] #[derive(Debug)]
struct Node<T> { struct Node<T> {
@ -27,21 +23,21 @@ struct Node<T> {
impl <T> List<T> { impl <T> List<T> {
pub fn new() -> Self { pub fn new() -> Self {
Self { head: Link::Empty } Self { head: None }
} }
pub fn push(&mut self, elem: T) { pub fn push(&mut self, elem: T) {
let new_node = Node { let new_node = Node {
elem: elem, elem: elem,
next: std::mem::replace(&mut self.head, Link::Empty), next: std::mem::replace(&mut self.head, None),
}; };
self.head = Link::More(Box::new(new_node)); self.head = Some(Box::new(new_node));
} }
pub fn pop(&mut self) -> Option<T> { pub fn pop(&mut self) -> Option<T> {
match std::mem::replace(&mut self.head, Link::Empty) { match std::mem::replace(&mut self.head, None) {
Link::Empty => None, None => None,
Link::More(node) => { Some(node) => {
self.head = node.next; self.head = node.next;
Some(node.elem) Some(node.elem)
} }