介绍

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

链表定义

我们重新定义链表如下:

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

type Link<T> = Option<Box<Node<T>>>;

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

new

pub fn new() -> Self {
List { head: None, tail: ptr::null_mut() }
}

push

下面我们来实现push,代码如下:

pub fn push(&mut self, elem: T)  {
let mut new_tail = Box::new(Node {
elem: elem,
next: None,
});

let raw_tail: *mut _ = &mut *new_tail;

if !self.tail.is_null() {
unsafe {//非安全代码
(*self.tail).next = Some(new_tail);
}
} else {
self.head = Some(new_tail);
}

self.tail = raw_tail;
}

pop

下面我们来实现pop,实现代码如下:

pub fn pop(&mut self) -> Option<T> {
self.head.take().map(|head| {
let head = *head;
self.head = head.next;

if self.head.is_none() {
self.tail = ptr::null_mut();
}
head.elem
})
}

测试代码

#[cfg(test)]
mod tests {
use super::List;

#[test]
fn basics() {
let mut list = List::new();
assert_eq!(list.pop(), None);

list.push(1);
list.push(2);
list.push(3);

assert_eq!(list.pop(), Some(1));
assert_eq!(list.pop(), Some(2));
list.push(4);
assert_eq!(list.pop(), Some(3));
assert_eq!(list.pop(), Some(4));
assert_eq!(list.pop(), None);
}
}

完整代码

use std::ptr;
pub struct List<T> {
head: Link<T>,
tail: *mut Node<T>,
}

type Link<T> = Option<Box<Node<T>>>;

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

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

pub fn push(&mut self, elem: T) {
let mut new_tail = Box::new(Node {
elem: elem,
next: None,
});

let raw_tail: *mut _ = &mut *new_tail;

if !self.tail.is_null() {
unsafe {
(*self.tail).next = Some(new_tail);
}
} else {
self.head = Some(new_tail);
}

self.tail = raw_tail;
}

pub fn pop(&mut self) -> Option<T> {
self.head.take().map(|head| {
let head = *head;
self.head = head.next;

if self.head.is_none() {
self.tail = ptr::null_mut();
}
head.elem
})
}
}

#[cfg(test)]
mod tests {
use super::List;

#[test]
fn basics() {
let mut list = List::new();
assert_eq!(list.pop(), None);

list.push(1);
list.push(2);
list.push(3);

assert_eq!(list.pop(), Some(1));
assert_eq!(list.pop(), Some(2));
list.push(4);
assert_eq!(list.pop(), Some(3));
assert_eq!(list.pop(), Some(4));
assert_eq!(list.pop(), None);
}
}