017 通过链表学Rust之实现元素添加

介绍

视频地址：https://www.bilibili.com/video/av78062009/
相关源码：https://github.com/anonymousGiga/Rust-link-list

详细内容

在上一节我们定义了我们的双链表，本节我们来给双链表创建new函数和pushfront函数。

new

impl<T> Node<T> {
  fn new(elem: T) -> Rc<RefCell<Self>> {
    Rc::new(RefCell::new(Node {
      elem: elem,
      prev: None,
      next: None,
    }))
  }
}

impl<T> List<T> {
  pub fn new() -> Self {
    List { head: None, tail: None }
  }
}

push_front

下面我们增加添加元素的函数，如下：

pub fn push_front(&mut self, elem: T) {
    let node = Node::new(elem);
    match self.head.take() {
      Some(head) => {
        head.borrow_mut().prev = Some(node.clone());
        node.borrow_mut().next = Some(head);
        self.head = Some(node);
      }
      None => {
        self.tail = Some(node.clone());
        self.head = Some(node);
      }
    }
  }

完整代码

添加后的完整代码如下：

use std::rc::Rc;
use std::cell::RefCell;

pub struct List<T> {
  head: Link<T>,
  tail: Link<T>,
}

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

struct Node<T> {
  elem: T,
  next: Link<T>,
  prev: Link<T>,
}

impl<T> Node<T> {
  fn new(elem: T) -> Rc<RefCell<Self>> {
    Rc::new(RefCell::new(Node {
      elem: elem,
      prev: None,
      next: None,
    }))
  }
}

impl<T> List<T> {
  pub fn new() -> Self {
    List { head: None, tail: None }
  }

  pub fn push_front(&mut self, elem: T) {
    let node = Node::new(elem);
    match self.head.take() {
      Some(head) => {
        head.borrow_mut().prev = Some(node.clone());

        node.borrow_mut().next = Some(head);
        self.head = Some(node);
      }

      None => {
        self.tail = Some(node.clone());
        self.head = Some(node);
      }
    }
  }
}