gistfile1.txt

use std::{rc::Rc, cell::RefCell, fmt::Display};

type Pointer<T> = Option<Rc<RefCell<Node<T>>>>;

struct Node<T> {
    data: T,
    next : Pointer<T>,
    prev : Pointer<T>,
}

impl<T> Node<T> {
    
    pub fn new(data: T, next: Pointer<T>, prev: Pointer<T>) -> Self {
        Node { data, next, prev }
    }
}

pub struct DoubleLinkedList<T> {

    first : Pointer<T>,
    last : Pointer<T>,
    size : u32,
}

impl<T> DoubleLinkedList<T> {
    
    pub fn new() -> Self {
        DoubleLinkedList { first : None, last: None, size : 0 }
    }

    pub fn push(&mut self, data: T) {

        let new_node = Some(Rc::new(RefCell::new(Node::new(data, None, self.last.clone()))));

        if self.first.is_none() { // first append
         
            self.first = new_node;
            self.last = self.first.clone();

        } else {

            if let Some(last_node_rc) = self.last.take() {
                let mut last_node = last_node_rc.as_ref().borrow_mut();
                last_node.next = new_node.clone();
            }
            self.last = new_node.clone();
        }
        self.size = self.size + 1;
    }

    pub fn empty(&self) -> bool {
        self.first.is_none()
    }

    pub fn len(&self) -> u32 {
        self.size
    }
}