update at 2020-06-23 18:08:26 by ehlxr
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26ab99279a
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@ -0,0 +1 @@
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千万千万群群无群无群无群无群所多所多
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126
src/main.rs
126
src/main.rs
@ -4,7 +4,7 @@ use std::ops::Deref;
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use std::rc::{Rc, Weak};
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use std::sync::{mpsc, Arc, Mutex};
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use std::time::Duration;
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use std::{collections::HashMap, fmt::Display, fs::File, io, io::ErrorKind, thread};
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use std::{collections::HashMap, fmt::Display, fs, fs::File, io, io::ErrorKind, thread};
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fn main() {
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let mut s = String::from("Hello");
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@ -216,7 +216,7 @@ fn main() {
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};
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println!("{:?}", f.metadata());
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match read_username_from_file() {
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match read_username_from_file("hello2.txt") {
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Ok(st) => println!("{}", st),
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Err(err) => panic!("There was a problem read string: {:?}", err),
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};
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@ -409,7 +409,7 @@ fn main() {
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leaf.parent.borrow().upgrade(),
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);
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} // -> 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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// weak_count 无需计数为 0 就能使 Rc<branch> 实例被清理。
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println!(
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"leaf strong = {}, weak = {}, parent = {:?}",
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Rc::strong_count(&leaf),
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@ -948,7 +948,7 @@ fn main() {
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let s1 = String::from("Hello, ");
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let s2 = String::from("World!");
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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!("{} {} {}", s1, s3, s2);
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println!("{} {}", s3, s2);
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let hello = "测试中文字符串";
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@ -1025,14 +1025,12 @@ fn main() {
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// File::create(fnames).unwrap()
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// }
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Err(e) => match e.kind() {
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ErrorKind::NotFound => {
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match File::create(fnames) {
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Ok(f) => f,
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Err(e) => panic!("Problem creating the file: {:?}", e),
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}
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}
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ErrorKind::NotFound => match File::create(fnames) {
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Ok(f) => f,
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Err(e) => panic!("Problem creating the file: {:?}", e),
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},
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oe => panic!("Problem opening the file: {:?}", oe),
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}
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},
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};
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println!("{:?}", file);
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@ -1040,7 +1038,49 @@ fn main() {
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let m = Message::Quit;
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match m {
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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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};
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println!("----------------错误传递--------------");
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let r = read_username_from_file("hello2.txt");
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match r {
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Ok(s) => println!("read from file result: {}", s),
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Err(e) => println!("read from file error: {:?}", e),
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};
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println!("--------------泛型--------------");
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let p = Point1 { x: 5, y: 10 };
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println!("p.x = {}", p.x());
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println!("p.y = {}", p.y());
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let p1 = Point1 { x: "hello", y: 'd' };
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let p2 = p.mixup(p1);
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println!("{:?}", p2);
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}
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#[derive(Debug)]
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struct Point1<T, U> {
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x: T,
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y: U,
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}
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impl<D, Z> Point1<D, Z> {
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fn x(&self) -> &D {
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&self.x
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}
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}
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impl Point1<i32, i32> {
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fn y(&self) -> i32 {
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self.y
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}
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}
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impl<T, U> Point1<T, U> {
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fn mixup<V, W>(self, p: Point1<V, W>) -> Point1<T, W> {
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Point1 { x: self.x, y: p.y }
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}
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}
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@ -1278,36 +1318,36 @@ mod performance_group {
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}
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}
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// 传播错误
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fn read_username_from_file() -> Result<String, io::Error> {
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/// 传播错误
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fn read_username_from_file(path: &str) -> Result<String, io::Error> {
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// 1.
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let f = File::open("hello.txt");
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let mut f = match f {
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Ok(file) => file,
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Err(error) => return Err(error),
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};
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let mut s = String::new();
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match f.read_to_string(&mut s) {
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Ok(_) => Ok(s),
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Err(e) => Err(e),
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}
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// let f = File::open(path);
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//
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// let mut f = match f {
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// Ok(file) => file,
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// Err(error) => return Err(error),
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// };
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//
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// let mut s = String::new();
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// match f.read_to_string(&mut s) {
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// Ok(_) => Ok(s),
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// Err(e) => Err(e),
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// }
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// 2.
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// let mut f = File::open("hello.txt")?;
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//
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// let mut s = String::new();
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// f.read_to_string(&mut s)?;
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// Ok(s)
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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)?;
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Ok(s)
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// 3.
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// let mut s = String::new();
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// File::open("hello.txt")?.read_to_string(&mut s)?;
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// Ok(s)
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// let mut s = String::new();
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// File::open(path)?.read_to_string(&mut s)?;
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// Ok(s)
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// 4.
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// fs::read_to_string("hello.txt")
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// fs::read_to_string(path)
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}
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trait Summary {
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@ -1347,9 +1387,9 @@ impl ToString for Tweet {
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//}
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fn notify<T, U>(t: &T, u: &U) -> String
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where
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T: Summary + ToString,
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U: Summary,
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where
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T: Summary + ToString,
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U: Summary,
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{
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format!("{}, {}", u.summarize(), t.to_string())
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}
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@ -1417,18 +1457,18 @@ fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
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}
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struct Cacher<T, D, F>
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where
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T: Fn(&D) -> F,
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where
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T: Fn(&D) -> F,
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{
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calculation: T,
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value: HashMap<D, F>,
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}
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impl<T, D, F> Cacher<T, D, F>
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where
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D: Hash + Eq,
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F: Copy,
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T: Fn(&D) -> F,
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where
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D: Hash + Eq,
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F: Copy,
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T: Fn(&D) -> F,
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{
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fn new(calculation: T) -> Cacher<T, D, F> {
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Self {
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