rust_study/src/main.rs

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use std::cell::RefCell;
use std::hash::Hash;
use std::ops::Deref;
use std::rc::{Rc, Weak};
use std::sync::{mpsc, Arc, Mutex};
use std::time::Duration;
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use std::{collections::HashMap, fmt::Display, fs, fs::File, io, io::ErrorKind, thread};
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fn main() {
let mut s = String::from("Hello");
s.push_str(", World!");
println!("{}", s);
let c: char = 'd';
println!("{}", c);
let x = 5;
// cannot assign twice to immutable variable
// x = x + 1;
// 使用 let 重新定义 x隐藏了之前 x 的值
let x = x + 1;
println!("The value of x is {}", x);
let x = "test";
println!("The value of x is {}", x);
// 可变变量
let mut x = 2;
x = x * 3;
// expected integer, found reference
// x = "test";
println!("The value of x is {}", x);
// : 指定变量类型
let mut y: i32 = 22;
println!("The value of y is {}", y);
y = 12;
println!("The value of y is {}", y);
// 可变引用
let mut s = String::from("hello");
let s1 = &mut s;
// 在特定作用域中的特定数据有且只有一个可变引用
// let s2 = &mut s;
change(s1);
println!("{}", s1);
{
let s2 = &mut s;
println!("{}", s2);
}
// 多个不可变引用是可以的
let r1 = &s;
let r2 = &s;
// 不能在拥有不可变引用的同时拥有可变引用
// let r3 = &mut s;
println!("{}, {}", r1, r2);
// ---------------------------
println!("----------------------------------------");
let home = IpAddr::V4(127, 0, 0, 1);
let loopback = IpAddr::V6(String::from("::1"));
println!("{:?}, {:?}", home, loopback);
let m = Message::Quit;
m.call();
let m = &Message::Move { x: 1, y: 2 };
match m {
Message::Move { x, y } => println!("x: {}, y: {}", x, y),
_ => {}
}
m.call();
let m = Message::Write(String::from("test"));
m.call();
let m = Message::ChangeColor(1, 2, 3);
m.call();
// ---------------------------
println!("----------------------------------------");
let my_str = String::from("hello world!");
// let my_str = "hello world!";
println!("{}, {}", my_str, first_words(&my_str[..]));
println!("get first word: {}", first_words("hello world"));
let rect = Rectangle {
width: 21,
height: 23,
};
println!(
"The area of the rectangle is {} square pixels.",
rect.area()
);
let rect1 = Rectangle {
width: 30,
height: 50,
};
let rect2 = Rectangle {
width: 10,
height: 40,
};
let rect3 = Rectangle {
width: 60,
height: 45,
};
println!("rect1 is {:#?}", rect1);
println!("Can rect1 hold rect2? {}", rect1.can_hold(&rect2));
println!("Can rect1 hold rect3? {}", rect1.can_hold(&rect3));
let rece4 = Rectangle::square(8);
println!(
"The area of the rectangle is {} square pixels.",
rece4.area()
);
// ---------------------------
println!("-----------------vec-----------------------");
let mut v = vec![100, 32, 57];
for i in &mut v {
*i += 50;
}
println!("{:?}", v);
// let mut v=Vec::new();
let v = vec![1, 2, 3, 4, 5, 6, 7, 8, 9];
let f = v.get(100);
println!("{:?}", f);
let f = &v[0];
println!("{}", f);
// v.push(12);
let d: Option<u32> = None;
println!("{:?} {}", d, d.is_none());
let s = Some("ddd");
println!("{:#?}", s);
let s: Option<u32> = Some(2);
println!("{},{}", s.unwrap(), s.is_some());
performance_group::clarinet_trio();
performance_group::instrument::clarinet();
let s1 = String::from("Hello");
let s2 = String::from("World");
// + == fn add(self, s: &str) -> String
// 这个语句会获取 s1 的所有权,附加上从 s2 中拷贝的内容,并返回结果的所有权
let s3 = s1 + &s2;
let s = format!("{}-{}", s2, s3);
println!("{}", s);
let hello = "你好";
println!("{}", hello.len()); // output: 6
let s = &hello[0..3]; // output: 你
println!("{}", s);
for c in hello.chars() {
println!("{}", c);
}
for b in hello.bytes() {
println!("{}", b);
}
// ---------------------------
println!("----------------------------------------");
let mut scores = HashMap::new();
scores.insert(String::from("Blue"), 10);
scores.insert(String::from("Yellow"), 50);
let team_name = String::from("Blue");
let score = scores.get(&team_name);
println!("{}", score.unwrap());
for (k, v) in scores.iter() {
println!("{}, {}", k, v)
}
scores.entry(String::from("Yellow")).or_insert(50);
let black = scores.entry(String::from("black")).or_insert(50);
// cannot borrow `scores` as immutable because it is also borrowed as mutable
// println!("{:?}, {}", scores, black);
println!("{}", black);
println!("{:#?}", scores);
let text = "hello world wonderful world";
let mut map = HashMap::new();
for word in text.split_whitespace() {
let count = map.entry(word).or_insert(0);
*count += 1;
}
println!("{:?}", map);
// ---------------------------
println!("----------------------------------------");
let f = match File::open("hello.txt") {
Ok(file) => file,
Err(error) => match error.kind() {
ErrorKind::NotFound => match File::create("hello.txt") {
Ok(file) => file,
Err(e) => panic!("Tried to create file but there was a problem: {:?}", e),
},
ot_err => panic!("There was a problem opening the file: {:?}", ot_err),
},
};
println!("{:?}", f.metadata());
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match read_username_from_file("hello2.txt") {
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Ok(st) => println!("{}", st),
Err(err) => panic!("There was a problem read string: {:?}", err),
};
let h: std::net::IpAddr = "127.0.0.1".parse().unwrap();
let s: String = "127.0.0.1".parse().unwrap();
println!("{:?}, {}", h, s);
let v = ["d", "fd"];
println!("{:?}", v);
let v = vec!["d", "fd"];
println!("{:?}", v);
// ---------------------------
println!("----------------------------------------");
let t = Tweet {
username: String::from("horse_ebooks"),
content: String::from("of course, as you probably already know, people"),
reply: false,
retweet: false,
};
let t1 = returns_summarizable();
println!("{}", notify(&t, &t1));
let number_list = vec![34, 50, 25, 100, 65];
let result = largest(&number_list);
println!("The largest number is {}", result);
let char_list = vec!['y', 'm', 'a', 'q'];
let result = largest(&char_list);
println!("The largest char is {}", result);
// ---------------------------
println!("----------------------------------------");
let p = Pair::new(String::from("t"), String::from("s"));
p.cmp_display();
let p = Pair::new(
Rectangle {
width: 2,
height: 3,
},
Rectangle {
width: 4,
height: 9,
},
);
println!("{:?}", p);
// no method named `cmp_display` found for type `Pair<Rectangle>` in the current scope
// p.cmp_display();
// ---------------------------
println!("----------------------------------------");
let s1 = String::from("abcd");
let r;
{
let s2 = String::from("qw");
r = longest(s1.as_str(), s2.as_ref());
println!("The longest string is {}", r);
}
// `s2` does not live long enough
// println!("The longest string is {}", r);
let closure = |x: u32| -> u32 { x + 2 };
// let closure = |x| x + 2;
println!("closure: {}", closure(3));
let mut s = String::from("hello");
let d = change;
d(&mut s);
println!("{}", s);
generate_workout(10, 3);
// ---------------------------
println!("----------------------------------------");
let x = 4;
let equal_to_x = |z| z == x;
println!("{}", equal_to_x(4));
let x = vec![1, 2, 3];
// move 强制闭包获取其使用的环境值的所有权
let equal_to_x = move |z| z == x;
//value used here after move
// println!("can't use x here: {:?}", x);
let y = vec![1, 2, 3];
println!("{}", equal_to_x(y));
let v1: Vec<i32> = vec![1, 2, 3];
let v2: Vec<_> = v1.iter().map(|x| x + 1).collect();
println!("{:?}", v2);
let shoes = vec![
Shoe {
size: 10,
style: String::from("sneaker"),
},
Shoe {
size: 13,
style: String::from("sandal"),
},
Shoe {
size: 10,
style: String::from("boot"),
},
];
let in_my_size = shoes_in_my_size(shoes, 10);
println!("{:?}", in_my_size);
let counter = Counter::new();
let v: Vec<_> = counter.into_iter().map(|x| x + 1).collect();
println!("{:?}", v);
let v: Vec<_> = Counter::new()
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.zip(Counter::new().skip(1))
.map(|(a, b)| a * b)
.collect();
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println!("{:?}", v);
let sum: u32 = Counter::new()
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.zip(Counter::new().skip(1))
.map(|(a, b)| a * b)
.filter(|x| x % 3 == 0)
.sum();
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println!("{}", sum);
// ---------------------------
println!("----------------------------------------");
use crate::List::*;
let a = Rc::new(Cons(5, RefCell::new(Rc::new(Nil))));
println!("a initial rc count = {}", Rc::strong_count(&a));
println!("a next item = {:?}", a.tail());
let b = Rc::new(Cons(10, RefCell::new(Rc::clone(&a))));
println!("a rc count after b creation = {}", Rc::strong_count(&a));
println!("b initial rc count = {}", Rc::strong_count(&b));
println!("b next item = {:?}", b.tail());
if let Some(link) = a.tail() {
*link.borrow_mut() = Rc::clone(&b);
}
println!("b rc count after changing a = {}", Rc::strong_count(&b));
println!("a rc count after changing a = {}", Rc::strong_count(&a));
// 这会导致栈溢出
// println!("a next item = {:?}", a.tail());
// 并不是 a.tail(); 引起死循环,打印函数触发循环引用
// ---------------------------
println!("----------------------------------------");
let leaf = Rc::new(Node {
value: 3,
parent: RefCell::new(Weak::new()),
children: RefCell::new(vec![]),
});
println!(
"leaf strong = {}, weak = {}, parent = {:?}",
Rc::strong_count(&leaf),
Rc::weak_count(&leaf),
leaf.parent.borrow().upgrade(),
);
{
let branch = Rc::new(Node {
value: 5,
parent: RefCell::new(Weak::new()),
children: RefCell::new(vec![Rc::clone(&leaf)]),
});
*leaf.parent.borrow_mut() = Rc::downgrade(&branch);
// let leaf = Rc::new(Node {
// value: 3,
// parent: RefCell::new(Rc::downgrade(&branch)),
// children: RefCell::new(vec![]),
// });
println!(
"branch strong = {}, weak = {}, parent = {:?}",
Rc::strong_count(&branch),
Rc::weak_count(&branch),
branch.parent.borrow().upgrade(),
);
println!(
"leaf strong = {}, weak = {}, parent = {:?}",
Rc::strong_count(&leaf),
Rc::weak_count(&leaf),
leaf.parent.borrow().upgrade(),
);
} // -> 离开作用域此时Rc<branch> 的强引用strong_count为 0但是 Weak<branch> 弱引用数weak_count仍然为 1引用 Weak<branch> 的 Rc<leaf> 仍然存在),
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// weak_count 无需计数为 0 就能使 Rc<branch> 实例被清理。
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println!(
"leaf strong = {}, weak = {}, parent = {:?}",
Rc::strong_count(&leaf),
Rc::weak_count(&leaf),
leaf.parent.borrow().upgrade(),
);
// ---------------------------
println!("----------------------------------------");
let x = Rc::new(5);
let y = *x;
assert_eq!(5, y);
let r = Rc::new("Rust".to_string());
// Rc 不支持解引用移动
// let x = *r;
// println!("{:?}", x);
println!("{:?}", *r);
let x = RefCell::new(5);
println!("{}", *x.borrow());
// 变量 x 非 mut可通过以下代码修改 x 的值
*x.borrow_mut() = 7;
println!("{}", *x.borrow());
let x = Box::new(5);
let x1 = *x;
println!("Box {}", x1);
// ---------------------------
println!("--------函数和方法的隐式解引用强制多态--------------");
// let m = Box::new(String::from("Rust"));
let m = MyBox::new(String::from("Rust"));
//String 上的 Deref 实现: fn deref(&self) -> &str {...}
// hello_str(&(*m)[..]);
// 当所涉及到的类型定义了 Deref traitRust 会分析这些类型并使用任意多次 Deref::deref 调用以获得匹配参数的类型
// &m -> &String -> &str
hello_str(&m);
// ---------------------------
println!("---------------------------");
let jh = thread::spawn(|| {
for i in 1..10 {
println!("hi number {} from the spawned thread!", i);
thread::sleep(Duration::from_millis(1));
}
});
for i in 1..5 {
println!("hi number {} from the main thread!", i);
thread::sleep(Duration::from_millis(1));
}
jh.join().unwrap();
let v = vec![1, 2, 3];
let handle = thread::spawn(move || {
println!("Here's a vector: {:?}", v);
});
// drop(v);
// ^ value used here after move
handle.join().unwrap();
// ---------------------------
println!("---------------------------");
let (tx, rx) = mpsc::channel();
let tx1 = mpsc::Sender::clone(&tx);
thread::spawn(move || {
let vals = vec![
String::from("hi"),
String::from("from"),
String::from("the"),
String::from("thread"),
];
for val in vals {
tx1.send(val).unwrap();
thread::sleep(Duration::from_millis(50));
}
});
thread::spawn(move || {
// tx.send(12).unwrap();
tx.send(String::from("12")).unwrap();
});
for received in rx {
println!("Got: {}", received);
}
// ---------------------------
println!("---------------------------");
let counter = Arc::new(Mutex::new(0));
let mut handles = vec![];
for _ in 0..10 {
let counter = Arc::clone(&counter);
let handle = thread::spawn(move || {
let mut num = counter.lock().unwrap();
*num += 1;
});
handles.push(handle);
}
for handle in handles {
handle.join().unwrap();
}
println!("Result: {}", *counter.lock().unwrap());
// ---------------------------
println!("---------------------------");
let screen = Screen {
components: vec![
Box::new(SelectBox {
width: 75,
height: 10,
options: vec![
String::from("Yes"),
String::from("Maybe"),
String::from("No"),
],
}),
Box::new(Button {
width: 50,
height: 10,
label: String::from("OK"),
}),
],
};
screen.run();
// ---------------------------
println!("---------------------------");
let bt = Bt {
height: 10,
label: Some(String::from("test")),
};
let h = bt.label.unwrap();
println!("{}", h);
// borrow of moved value: `bt`
// println!("{:?}", bt);
// ---------------------------
println!("---------------------------");
let favorite_color: Option<&str> = None;
let is_tuesday = false;
let age: Result<u8, _> = "34".parse();
if let Some(color) = favorite_color {
println!("Using your favorite color, {}, as the background", color);
} else if is_tuesday {
println!("Tuesday is green day!");
} else if let Ok(age) = age {
if age > 30 {
println!("Using purple as the background color");
} else {
println!("Using orange as the background color");
}
} else {
println!("Using blue as the background color");
}
let mut stack = Vec::new();
stack.push(1);
stack.push(2);
stack.push(3);
while let Some(top) = stack.pop() {
println!("{}", top);
}
let v = vec!['a', 'b', 'c'];
for (index, value) in v.iter().enumerate() {
println!("{} is at index {}", value, index);
}
let x: u32 = 5;
let point = (3, x as i32);
print_coordinates(&point);
// ---------------------------
println!("---------------------------");
// 匹配字面值
let x = 1;
match x {
1 => println!("one"),
2 => println!("two"),
3 => println!("three"),
_ => println!("anything"),
}
// 匹配命名变量
let x = Some(5);
let y = 10;
match x {
Some(50) => println!("Got 50"),
Some(y) => println!("Matched, y = {:?}", y),
_ => println!("Default case, x = {:?}", x),
}
println!("at the end: x = {:?}, y = {:?}", x, y);
// 多个模式
let x = 1;
match x {
1 | 2 => println!("one or two"),
3 => println!("three"),
_ => println!("anything"),
}
// 通过 ... 匹配值的范围
// 范围只允许用于数字或 char 值
let x = 5;
match x {
1...5 => println!("one through five"),
_ => println!("something else"),
}
let x = 'c';
match x {
'a'...'j' => println!("early ASCII letter"),
'k'...'z' => println!("late ASCII letter"),
_ => println!("something else"),
}
// 解构结构体
struct Point {
x: i32,
y: i32,
}
let p = Point { x: 0, y: 7 };
let Point { x: a, y: b } = p;
assert_eq!(0, a);
assert_eq!(7, b);
let Point { x, y } = p;
assert_eq!(0, x);
assert_eq!(7, y);
match p {
Point { x, y: 0 } => println!("On the x axis at {}", x),
Point { x: 0, y } => println!("On the y axis at {}", y),
Point { x, y } => println!("On neither axis: ({}, {})", x, y),
}
// 解构枚举
// let msg = Message::ChangeColor(0, 160, 255);
let msg = &Message::Move { x: 1, y: 2 };
// let msg = &Message::Quit;
match msg {
Message::Quit => println!("The Quit variant has no data to destructure."),
Message::Move { x, y } => {
println!("Move in the x direction {} and in the y direction {}", x, y);
}
Message::Write(text) => println!("Text message: {}", text),
Message::ChangeColor(r, g, b) => {
println!("Change the color to red {}, green {}, and blue {}", r, g, b)
}
}
// 解构嵌套的结构体 & 枚举
let msg = Msg::ChangeColor(Color::Hsv(0, 160, 255));
match msg {
Msg::ChangeColor(Color::_Rgb(r, g, b)) => {
println!("Change the color to red {}, green {}, and blue {}", r, g, b)
}
Msg::ChangeColor(Color::Hsv(h, s, v)) => println!(
"Change the color to hue {}, saturation {}, and value {}",
h, s, v
),
_ => (),
}
// 解构引用
let points = vec![
Point { x: 0, y: 0 },
Point { x: 1, y: 5 },
Point { x: 10, y: -3 },
];
let sum_of_squares: i32 = points.iter().map(|&Point { x, y }| x * x + y * y).sum();
println!("{}", sum_of_squares);
// 解构结构体和元组
let ((feet, inches), Point { x, y }) = ((3, 10), Point { x: 3, y: -10 });
println!("{} {} {} {}", feet, inches, x, y);
// 忽略模式中的值
foo(3, 4);
fn foo(_: i32, y: i32) {
println!("This code only uses the y parameter: {}", y);
}
let mut setting_value = Some(5);
let new_setting_value = Some(10);
match (setting_value, new_setting_value) {
(Some(_), Some(_)) => {
println!("Can't overwrite an existing customized value");
}
_ => {
setting_value = new_setting_value;
}
}
println!("setting is {:?}", setting_value);
let numbers = (2, 4, 8, 16, 32);
match numbers {
(first, _, third, _, fifth) => println!("Some numbers: {}, {}, {}", first, third, fifth),
}
match numbers {
(first, .., last) => println!("Some numbers: {}, {}", first, last),
// error: `..` can only be used once per tuple or tuple struct pattern
// (.., second, ..) => println!("Some numbers: {}", second),
}
// 通过在名字前以一个下划线开头来忽略未使用的变量
let _x = 5;
// let y = 10;
// ^ help: consider prefixing with an underscore: `_y`
struct Pt {
x: i32,
_y: i32,
_z: i32,
}
let origin = Pt { x: 0, _y: 0, _z: 0 };
match origin {
Pt { x, .. } => println!("x is {}", x),
}
// 匹配守卫提供的额外条件
let num = Some(4);
match num {
Some(x) if x < 5 => println!("less than five: {}", x),
Some(x) => println!("{}", x),
None => (),
}
let x = 4;
let y = true;
match x {
// 匹配守卫中引用外部变量 y而不是创建新变量 y
// if 条件作用于整个 4 | 5 | 6 模式,类似:(4 | 5 | 6) if y => println!("yes"),
4 | 5 | 6 if y => println!("yes"),
_ => println!("no"),
}
// 使用 @ 可以在一个模式中同时测试和保存变量值。
enum Ms {
Hello { id: i32 },
}
let msg = Ms::Hello { id: 5 };
match msg {
Ms::Hello { id: id_var @ 3...7 } => println!("Found an id in range: {}", id_var),
// 此匹配分支不能使用 id
Ms::Hello { id: 10...12 } => println!("Found an id in another range"),
Ms::Hello { id } => println!("Found some other id: {}", id),
}
// 遗留模式: ref 和 ref mut
let robot_name = &Some(String::from("Bors"));
match robot_name {
Some(name) => println!("Found a name: {}", name),
// 老版本中会如下使用
// &Some(ref name) => println!("Found a name: {}", name),
None => (),
}
println!("robot_name is: {:?}", robot_name);
// ---------------------------
println!("---------------------------");
let mut num = 5;
let r1 = &num as *const i32; // 不可变的裸指针
let r2 = &mut num as *mut i32; // 可变的裸指针
unsafe {
println!("r1 is: {}", *r1);
println!("r2 is: {}", *r2);
}
unsafe fn dangerous() {
println!("this dangerous function");
}
unsafe {
dangerous();
}
let mut v = vec![1, 2, 3, 4, 5, 6];
let r = &mut v[..];
// let (a, b) = r.split_at_mut(3);
let (a, b) = split_at_mut(r, 3);
println!("{:?}", a);
println!("{:?}", b);
// 使用 extern 函数调用外部 C 语言代码
extern "C" {
fn abs(input: i32) -> i32;
}
unsafe {
println!("Absolute value of -3 according to C: {}", abs(-3));
}
// 定义可供 C 语言调用的函数
#[no_mangle]
pub extern "C" fn call_from_c() {
println!("Just called a Rust function from C!");
}
// 静态变量
// 访问不可变静态变量是安全的
static HELLO_WORLD: &str = "Hello, world!";
println!("name is: {}", HELLO_WORLD);
// 访问和修改可变静态变量都是 不安全 的
add_to_count(3);
unsafe {
println!("COUNTER: {}", COUNTER);
}
unsafe trait Foo {
// methods go here
}
unsafe impl Foo for i32 {
// method implementations go here
}
// ---------------------------
println!("---------------------------");
struct Context<'s>(&'s str);
// 声明一个不短于 'c 的生命周期 's。
// struct Parser<'c, 's: 'c> {
struct Parser<'c, 's> {
context: &'c Context<'s>,
}
impl<'c, 's> Parser<'c, 's> {
fn parse(&self) -> Result<(), &'s str> {
Err(&self.context.0[1..])
}
}
fn parse_context(context: Context) -> Result<(), &str> {
Parser { context: &context }.parse()
}
let centext = Context("test");
match parse_context(centext) {
Err(s) => println!("{}", s),
_ => (),
}
// ---------------------------
println!("---------------------------");
trait Red {}
struct Ball<'a> {
diameter: &'a i32,
}
// impl<'a> Red for Ball<'a> {}
impl Red for Ball<'_> {}
let num = 5;
let obj = Box::new(Ball { diameter: &num }) as Box<dyn Red>;
// ---------------------------
println!("---------------------------");
struct StrWrap<'a>(&'a str);
// '_ 表明在此处使用省略的生命周期,这意味着我们仍然知道 StrWrap 包含一个引用,不过无需所有的生命周期注解来知道。
// fn foo<'a>(string: &'a str) -> StrWrap<'a> {
fn fsw(string: &str) -> StrWrap<'_> {
StrWrap(string)
}
// ---------------------------
println!("---------------------------");
fn add_one(x: i32) -> i32 {
x + 1
}
fn do_twice(f: fn(i32) -> i32, arg: i32) -> i32 {
f(arg) + f(arg)
}
let answer = do_twice(add_one, 5);
println!("The answer is: {}", answer);
// ---------------------------
println!("---------------------------");
let list_of_numbers = vec![1, 2, 3];
let list_of_strings: Vec<String> = list_of_numbers.iter().map(ToString::to_string).collect();
// let list_of_strings: Vec<String> = list_of_numbers.iter().map(|i| i.to_string()).collect();
println!("{:?}", list_of_strings);
#[derive(Debug)]
enum Status {
Value(u32),
Stop,
}
let list_of_statuses: Vec<Status> = (0u32..20).map(Status::Value).collect();
// let list_of_statuses: Vec<Status> = (0u32..20).map(|i| Status::Value(i)).collect();
println!("{:?}", list_of_statuses);
fn returns_closure() -> Box<dyn Fn(i32) -> i32> {
Box::new(|x| x + 1)
}
let rc = returns_closure();
println!("{}", rc(12));
// ---------------------------
println!("---------------------------");
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// use hello_macro::HelloMacro;
// use hello_macro_derive::HelloMacro;
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// #[derive(HelloMacro)]
// struct Pancakes;
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// Pancakes::hello_macro();
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let user1 = User {
username: String::from("hllo"),
email: String::from("hell@world.com"),
sign_in_count: 1,
active: false,
};
println!("{:?}", user1);
let s: &str = "Hello";
println!("{}", s);
let mut s: String = "Hello".to_string();
let w = "World";
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s.push_str(w); // 并不需要获取 w 的所有权
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s.push('!');
println!("{} {}", s, w);
let t = (1, "34");
test_tuple(t);
println!("{} {}", t.0, t.1);
let s1 = String::from("Hello, ");
let s2 = String::from("World!");
let s3 = s1 + &s2; // 注意 s1 被移动了,不能继续使用
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// println!("{} {} {}", s1, s3, s2);
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println!("{} {}", s3, s2);
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let hello = "测试中文字符串";
for c in hello.chars() {
print!("{} ", c);
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}
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println!("");
for b in hello.bytes() {
print!("{} ", b);
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}
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println!("");
// let s = hello[1]; // Rust 的字符串不支持索引
// let s = &hello[0..4]; // thread 'main' panicked at 'byte index 4 is not a char boundary; it is inside '试' (bytes 3..6) of `测试中文字符串`', src/libcore/str/mod.rs:2219:5
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println!("{}", &hello[0..3]);
println!("--------------HashMap-----------");
let mut scores = HashMap::new();
scores.insert(String::from("Blue"), 10);
scores.insert(String::from("Yellow"), 50);
println!("{:?}", scores);
for (k, v) in &scores {
println!("k {}, v {}", k, v);
}
// 只在键没有对应值时插入
// Entry 的 or_insert 方法在键对应的值存在时就返回这个值的 Entry
// 如果不存在则将参数作为新值插入并返回修改过的 Entry
let x3 = scores.entry("Blue".to_string()).or_insert(60);
println!("{}", x3);
let x2 = scores.entry("Red".to_string()).or_insert(55);
println!("{}", x2);
println!("{:?}", scores);
let nms = vec![String::from("Blue"), String::from("Yellow")];
let scs = vec![10, 50];
let scores: HashMap<_, _> = nms.iter().zip(scs.iter()).collect();
println!("{:?}", scores);
let field_name = String::from("hello");
let field_value = 456;
let mut map1 = HashMap::new();
map1.insert(field_name, field_value);
// borrow of moved value: `field_name`
// println!("{} {} {:?}", field_name, field_value, map1);
println!("{} {:?}", field_value, map1);
let k = &String::from("hello");
let v = String::from("world");
let mut map1 = HashMap::new();
map1.insert(k, v);
// borrow of moved value: `v`
// println!("{} {} {:?}", k, v, map1);
println!("{} {:?}", *k, map1);
let option = map1.get(k);
println!("{}", option.unwrap());
let text = "hello world wonderful world";
let mut map = HashMap::new();
for tex in text.split_whitespace() {
let counts = map.entry(tex).or_insert(0);
*counts += 1;
}
println!("{:?}", map);
println!("----------------错误处理-----------------");
let fnames = "hello2.txt";
let result = File::open(fnames);
let file = match result {
Ok(f) => f,
// Err(e) => {
// println!("Problem opening the file: {:?}", e);
//
// File::create(fnames).unwrap()
// }
Err(e) => match e.kind() {
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ErrorKind::NotFound => match File::create(fnames) {
Ok(f) => f,
Err(e) => panic!("Problem creating the file: {:?}", e),
},
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oe => panic!("Problem opening the file: {:?}", oe),
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},
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};
println!("{:?}", file);
println!("----------------match 匹配 枚举------------------");
let m = Message::Quit;
match m {
Message::Write(s) => println!("{}", s),
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// 此处可使用任意字符匹配其它情况
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abc => println!("{:?}", abc),
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};
println!("----------------错误传递--------------");
let r = read_username_from_file("hello2.txt");
match r {
Ok(s) => println!("read from file result: {}", s),
Err(e) => println!("read from file error: {:?}", e),
};
println!("--------------泛型--------------");
let p = Point1 { x: 5, y: 10 };
println!("p.x = {}", p.x());
println!("p.y = {}", p.y());
let p1 = Point1 { x: "hello", y: 'd' };
let p2 = p.mixup(p1);
println!("{:?}", p2);
}
#[derive(Debug)]
struct Point1<T, U> {
x: T,
y: U,
}
impl<D, Z> Point1<D, Z> {
fn x(&self) -> &D {
&self.x
}
}
impl Point1<i32, i32> {
fn y(&self) -> i32 {
self.y
}
}
impl<T, U> Point1<T, U> {
fn mixup<V, W>(self, p: Point1<V, W>) -> Point1<T, W> {
Point1 { x: self.x, y: p.y }
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}
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}
fn test_tuple(t: (i32, &str)) {
println!("{} {}", t.0, t.1);
}
#[derive(Debug)]
struct User {
username: String,
email: String,
sign_in_count: u64,
active: bool,
}
static mut COUNTER: u32 = 0;
fn add_to_count(inc: u32) {
unsafe {
COUNTER += inc;
}
}
use std::io::Read;
use std::slice;
fn split_at_mut(slice: &mut [i32], mid: usize) -> (&mut [i32], &mut [i32]) {
// let len = slice.len();
// assert!(mid <= len);
// (&mut slice[..mid], &mut slice[mid..])
let len = slice.len();
let ptr = slice.as_mut_ptr();
assert!(mid <= len);
unsafe {
(
slice::from_raw_parts_mut(ptr, mid),
slice::from_raw_parts_mut(ptr.offset(mid as isize), len - mid),
)
}
}
fn print_coordinates(&(x, y): &(i32, i32)) {
println!("Current location: ({}, {})", x, y);
}
#[derive(Debug)]
struct Bt {
height: u32,
label: Option<String>,
}
#[derive(Debug)]
struct SelectBox {
width: u32,
height: u32,
options: Vec<String>,
}
impl Draw for SelectBox {
fn draw(&self) {
// code to actually draw a select box
println!("{:?}", self);
}
}
#[derive(Debug)]
pub struct Button {
pub width: u32,
pub height: u32,
pub label: String,
}
impl Draw for Button {
fn draw(&self) {
// 实际绘制按钮的代码
println!("{:?}", self);
}
}
pub struct Screen {
pub components: Vec<Box<dyn Draw>>,
}
impl Screen {
pub fn run(&self) {
for component in self.components.iter() {
component.draw();
}
}
}
pub trait Draw {
fn draw(&self);
}
struct MyBox<T>(T);
impl<T> MyBox<T> {
fn new(x: T) -> MyBox<T> {
MyBox(x)
}
}
impl<T> Deref for MyBox<T> {
type Target = T;
fn deref(&self) -> &T {
&self.0
}
}
fn hello_str(name: &str) {
println!("Hello, {}!", name);
}
#[derive(Debug)]
enum List {
Cons(i32, RefCell<Rc<List>>),
Nil,
}
impl List {
fn tail(&self) -> Option<&RefCell<Rc<List>>> {
use crate::List::*;
match self {
Cons(_, item) => Some(item),
Nil => None,
}
}
}
#[derive(Debug)]
struct Node {
value: i32,
parent: RefCell<Weak<Node>>,
children: RefCell<Vec<Rc<Node>>>,
}
fn change(some_string: &mut String) {
some_string.push_str(", world");
}
//enum IpAddrKind {
// V4,
// V6,
//}
#[derive(Debug)]
enum IpAddr {
V4(u8, u8, u8, u8),
V6(String),
}
enum Color {
_Rgb(i32, i32, i32),
Hsv(i32, i32, i32),
}
enum Msg {
_Quit,
ChangeColor(Color),
}
// Quit 没有关联任何数据。
// Move 包含一个匿名结构体。
// Write 包含单独一个 String。
// ChangeColor 包含三个 i32。
#[derive(Debug)]
enum Message {
Quit,
Move { x: i32, y: i32 },
Write(String),
ChangeColor(i32, i32, i32),
}
impl Message {
fn call(&self) {
println!("this message call.");
}
}
//fn first_words<'a>(s: &'a str) -> &'a str {
fn first_words(s: &str) -> &str {
let b = s.as_bytes();
for (i, &item) in b.iter().enumerate() {
if item == b' ' {
return &s[0..i];
}
}
&s[..]
}
#[derive(Debug)]
struct Rectangle {
width: u32,
height: u32,
}
impl Rectangle {
fn area(&self) -> u32 {
self.width * self.height
}
fn can_hold(&self, other: &Rectangle) -> bool {
self.width > other.width && self.height > other.height
}
fn square(size: u32) -> Rectangle {
Rectangle {
width: size,
height: size,
}
}
}
mod sound {
pub mod instrument {
pub fn clarinet() {
println!("this clarinet");
}
}
}
mod performance_group {
pub use crate::sound::instrument;
pub fn clarinet_trio() {
instrument::clarinet();
instrument::clarinet();
instrument::clarinet();
}
}
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/// 传播错误
fn read_username_from_file(path: &str) -> Result<String, io::Error> {
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// 1.
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// let f = File::open(path);
//
// let mut f = match f {
// Ok(file) => file,
// Err(error) => return Err(error),
// };
//
// let mut s = String::new();
// match f.read_to_string(&mut s) {
// Ok(_) => Ok(s),
// Err(e) => Err(e),
// }
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// 2.
let mut f = File::open(path)?;
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let mut s = String::new();
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f.read_to_string(&mut s)?;
Ok(s)
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// 3.
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// let mut s = String::new();
// File::open(path)?.read_to_string(&mut s)?;
// Ok(s)
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// 4.
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// fs::read_to_string(path)
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}
trait Summary {
fn summarize_author(&self) -> String;
fn summarize(&self) -> String {
format!("(Read more from {}...)", self.summarize_author())
}
}
#[derive(Debug)]
struct Tweet {
pub username: String,
pub content: String,
pub reply: bool,
pub retweet: bool,
}
impl Summary for Tweet {
fn summarize_author(&self) -> String {
format!("@{}", self.username)
}
}
impl ToString for Tweet {
fn to_string(&self) -> String {
format!("{:?}", self)
}
}
//fn notify<T: Summary + ToString, U: Summary>(t: &T, u: &U) -> String {
// format!("{}, {}", u.summarize(), t.to_string())
//}
//fn notify(t: &(impl Summary + ToString), u: &(impl Summary)) -> String {
// format!("{}, {}", u.summarize(), t.to_string())
//}
fn notify<T, U>(t: &T, u: &U) -> String
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where
T: Summary + ToString,
U: Summary,
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{
format!("{}, {}", u.summarize(), t.to_string())
}
// 返回实现了指定 trait 的方法
fn returns_summarizable() -> impl Summary {
Tweet {
username: String::from("horse_ebooks"),
content: String::from("of course, as you probably already know, people"),
reply: false,
retweet: false,
}
}
fn largest<T: PartialOrd + Copy>(list: &[T]) -> T {
//fn largest(list: &[impl PartialOrd + Copy]) -> impl PartialOrd + Copy {
//fn largest<T>(list: &[T]) -> T
// where T: PartialOrd + Copy {
let mut largest = list[0];
for &item in list.iter() {
if item > largest {
largest = item;
}
}
// for item in list.iter() {
// if *item > largest {
// largest = *item;
// }
// }
return largest;
}
#[derive(Debug)]
struct Pair<T> {
x: T,
y: T,
}
impl<T> Pair<T> {
fn new(x: T, y: T) -> Self {
Self { x, y }
}
}
// 只有那些为 T 类型实现了 PartialOrd trait来允许比较和 Display trait来启用打印的 Pair<T> 才会实现 cmp_display 方法
impl<T: Display + PartialOrd> Pair<T> {
fn cmp_display(&self) {
if self.x >= self.y {
println!("The largest member is x = {}", self.x);
} else {
println!("The largest member is y = {}", self.y);
}
}
}
fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
if x.len() > y.len() {
x
} else {
y
}
}
struct Cacher<T, D, F>
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where
T: Fn(&D) -> F,
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{
calculation: T,
value: HashMap<D, F>,
}
impl<T, D, F> Cacher<T, D, F>
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where
D: Hash + Eq,
F: Copy,
T: Fn(&D) -> F,
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{
fn new(calculation: T) -> Cacher<T, D, F> {
Self {
calculation,
value: HashMap::<D, F>::new(),
}
}
fn value(&mut self, args: D) -> F {
match self.value.get(&args) {
Some(&v) => v,
None => {
let v = (self.calculation)(&args);
let v1 = v.clone();
self.value.insert(args, v);
v1
}
}
}
}
fn generate_workout(intensity: u32, random_number: u32) {
// let calculation = |num: u32| -> u32 {
// println!("calculating slowly...");
// thread::sleep(Duration::from_secs(2));
// num
// };
let mut expensive_result = Cacher::new(|num| {
println!("calculating slowly...");
thread::sleep(Duration::from_millis(500));
num + 1
});
if intensity < 25 {
println!("Today, do {} pushups!", expensive_result.value(intensity));
println!("Next, do {} situps!", expensive_result.value(intensity));
} else {
if random_number == 3 {
println!("Take a break today! Remember to stay hydrated!");
} else {
println!(
"Today, run for {} minutes!",
expensive_result.value(intensity)
);
}
}
}
#[derive(Debug)]
struct Shoe {
size: u32,
style: String,
}
fn shoes_in_my_size(shoes: Vec<Shoe>, shoe_size: u32) -> Vec<Shoe> {
shoes
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// .iter() // a collection of type `std::vec::Vec<Shoe>` cannot be built from `std::iter::Iterator<Item=&Shoe>`
.into_iter() //获取 vector 所有权的迭代器
.filter(|s| s.size == shoe_size)
.collect()
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}
struct Counter {
count: u32,
}
impl Counter {
fn new() -> Counter {
Counter { count: 0 }
}
}
impl Iterator for Counter {
type Item = u32;
fn next(&mut self) -> Option<Self::Item> {
self.count += 1;
if self.count < 6 {
Some(self.count)
} else {
None
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn call_with_different_values() {
let mut c = Cacher::new(|a| {
println!("cal: {}", a);
a + 1
});
let v1 = c.value(2);
let v1 = c.value(2);
assert_eq!(v1, 3);
let v2 = c.value(-2);
assert_eq!(v2, -1);
}
#[test]
fn call_with_different_type() {
let mut c = Cacher::new(|a| {
println!("\ncal: {}", a);
7
});
let v = c.value("tetsss");
assert_eq!(v, 7);
}
#[test]
fn iterator_demonstration() {
let v1 = vec![1, 2, 3];
let mut v1_iter = v1.iter();
assert_eq!(v1_iter.next(), Some(&1));
assert_eq!(v1_iter.next(), Some(&2));
assert_eq!(v1_iter.next(), Some(&3));
assert_eq!(v1_iter.next(), None);
}
#[test]
fn iterator_sum() {
let v1 = vec![1, 2, 3];
let v1_iter = v1.iter();
let total: i32 = v1_iter.sum();
assert_eq!(total, 6);
}
}