러스트 초보의 단일 Linked List 만들어보기

linked_list.rs

#[derive(Debug)]
struct LinkedList<T> {
    head: Option<Box<Node<T>>>,
    length: usize
}

#[derive(Debug)]
struct Node<T> {
    element: T,
    next: Option<Box<Node<T>>>
}

impl<T> LinkedList<T> {
    fn new() -> Self {
        LinkedList {
            head: None,
            length: 0
        }
    }

    fn length(&self) -> usize {
        self.length
    }

    fn push_front(&mut self, element: T) {
        let node = Node {
            element,
            next: self.head.take()
        };

        self.head = Some(Box::new(node));
        self.length += 1;
    }

    fn is_empty(&self) -> bool {
        match self.length {
            0 => true,
            _ => false
        }
    }

    fn pop_front(&mut self) {
        if !self.is_empty() {
            let prev_head = self.head.take();
            self.head = prev_head.unwrap().next;
        }
    }

    fn peek(&self) -> Option<&T> {
        match self.head {
            Some(ref node) => {
                Some(&node.element)
            },
            None => None
        }
    }
}

fn main() {
    let mut list = LinkedList::new();
    for i in (0..4).rev() {
        list.push_front(i);
    }

    println!("front: {:?}", list.peek());
    list.pop_front();
    println!("front: {:?}", list.peek());
    list.push_front(5);
    println!("front: {:?}", list.peek());

    println!("{:#?}", list);
}