【rCore OS 开源操作系统】Rust 练习题题解: Enums

【rCore OS 开源操作系统】Rust 练习题题解: Enums

摘要

rCore OS 开源操作系统训练营学习中的代码练习部分。
在此记录下自己学习过程中的产物，以便于日后更有“收获感”。
后续还会继续完成其他章节的练习题题解。

正文

enums1

题目

// enums1.rs
//
// No hints this time! ;)// I AM NOT DONE#[derive(Debug)]
enum Message {// TODO: define a few types of messages as used below
}fn main() {println!("{:?}", Message::Quit);println!("{:?}", Message::Echo);println!("{:?}", Message::Move);println!("{:?}", Message::ChangeColor);
}

题解

目测就是基本的枚举值语法。
甚至简单到题目中出现了 No hints this time! ;)，不会做那就有点汗颜了。

参考资料：https://doc.rust-lang.org/stable/book/ch06-01-defining-an-enum.html

// enums1.rs
//
// No hints this time! ;)#[derive(Debug)]
enum Message {// TODO: define a few types of messages as used below
}fn main() {println!("{:?}", Message::Quit);println!("{:?}", Message::Echo);println!("{:?}", Message::Move);println!("{:?}", Message::ChangeColor);
}

enums2

这里的核心知识点是，枚举与数据类型关联。

题目

// enums2.rs
//
// Execute `rustlings hint enums2` or use the `hint` watch subcommand for a
// hint.// I AM NOT DONE#[derive(Debug)]
enum Message {// TODO: define the different variants used below
}impl Message {fn call(&self) {println!("{:?}", self);}
}fn main() {let messages = [Message::Move { x: 10, y: 30 },Message::Echo(String::from("hello world")),Message::ChangeColor(200, 255, 255),Message::Quit,];for message in &messages {message.call();}
}

题解

题解与上面一样。

// enums2.rs
//
// Execute `rustlings hint enums2` or use the `hint` watch subcommand for a
// hint.#[derive(Debug)]
enum Message {// TODO: define the different variants used belowMove { x: i32, y: i32 },Echo(String),ChangeColor(i32, i32, i32),Quit,
}impl Message {fn call(&self) {println!("{:?}", self);}
}fn main() {let messages = [Message::Move { x: 10, y: 30 },Message::Echo(String::from("hello world")),Message::ChangeColor(200, 255, 255),Message::Quit,];for message in &messages {message.call();}
}

enums3

题目

// enums3.rs
//
// Address all the TODOs to make the tests pass!
//
// Execute `rustlings hint enums3` or use the `hint` watch subcommand for a
// hint.// I AM NOT DONEenum Message {// TODO: implement the message variant types based on their usage below
}struct Point {x: u8,y: u8,
}struct State {color: (u8, u8, u8),position: Point,quit: bool,message: String
}impl State {fn change_color(&mut self, color: (u8, u8, u8)) {self.color = color;}fn quit(&mut self) {self.quit = true;}fn echo(&mut self, s: String) { self.message = s }fn move_position(&mut self, p: Point) {self.position = p;}fn process(&mut self, message: Message) {// TODO: create a match expression to process the different message// variants// Remember: When passing a tuple as a function argument, you'll need// extra parentheses: fn function((t, u, p, l, e))}
}#[cfg(test)]
mod tests {use super::*;#[test]fn test_match_message_call() {let mut state = State {quit: false,position: Point { x: 0, y: 0 },color: (0, 0, 0),message: "hello world".to_string(),};state.process(Message::ChangeColor(255, 0, 255));state.process(Message::Echo(String::from("hello world")));state.process(Message::Move(Point { x: 10, y: 15 }));state.process(Message::Quit);assert_eq!(state.color, (255, 0, 255));assert_eq!(state.position.x, 10);assert_eq!(state.position.y, 15);assert_eq!(state.quit, true);assert_eq!(state.message, "hello world");}
}

题解

在要求会用枚举的基础上，结合了常常配合枚举一起使用的模式匹配。

// enums3.rs
//
// Address all the TODOs to make the tests pass!
//
// Execute `rustlings hint enums3` or use the `hint` watch subcommand for a
// hint.enum Message {// TODO: implement the message variant types based on their usage belowChangeColor(u8, u8, u8),Echo(String),Move(Point),Quit,
}struct Point {x: u8,y: u8,
}struct State {color: (u8, u8, u8),position: Point,quit: bool,message: String,
}impl State {fn change_color(&mut self, color: (u8, u8, u8)) {self.color = color;}fn quit(&mut self) {self.quit = true;}fn echo(&mut self, s: String) {self.message = s}fn move_position(&mut self, p: Point) {self.position = p;}fn process(&mut self, message: Message) {// TODO: create a match expression to process the different message// variants// Remember: When passing a tuple as a function argument, you'll need// extra parentheses: fn function((t, u, p, l, e))match message {Message::ChangeColor(r, g, b) => self.change_color((r, g, b)),Message::Echo(string) => self.echo(string),Message::Move(point) => self.move_position(point),Message::Quit => self.quit(),}}
}#[cfg(test)]
mod tests {use super::*;#[test]fn test_match_message_call() {let mut state = State {quit: false,position: Point { x: 0, y: 0 },color: (0, 0, 0),message: "hello world".to_string(),};state.process(Message::ChangeColor(255, 0, 255));state.process(Message::Echo(String::from("hello world")));state.process(Message::Move(Point { x: 10, y: 15 }));state.process(Message::Quit);assert_eq!(state.color, (255, 0, 255));assert_eq!(state.position.x, 10);assert_eq!(state.position.y, 15);assert_eq!(state.quit, true);assert_eq!(state.message, "hello world");}
}