update at 2020-06-16 18:18:40 by ehlxr
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parent
4c9a6dec3c
commit
939f409503
63
src/main.rs
63
src/main.rs
@ -331,15 +331,15 @@ fn main() {
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let v: Vec<_> = counter.into_iter().map(|x| x + 1).collect();
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println!("{:?}", v);
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let v: Vec<_> = Counter::new()
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.zip(Counter::new().skip(1))
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.map(|(a, b)| a * b)
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.collect();
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.zip(Counter::new().skip(1))
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.map(|(a, b)| a * b)
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.collect();
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println!("{:?}", v);
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let sum: u32 = Counter::new()
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.zip(Counter::new().skip(1))
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.map(|(a, b)| a * b)
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.filter(|x| x % 3 == 0)
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.sum();
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.zip(Counter::new().skip(1))
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.map(|(a, b)| a * b)
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.filter(|x| x % 3 == 0)
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.sum();
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println!("{}", sum);
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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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@ -937,7 +937,7 @@ fn main() {
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println!("{}", s);
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let mut s: String = "Hello".to_string();
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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_str(w); // 并不需要获取 w 的所有权
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s.push('!');
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println!("{} {}", s, w);
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@ -948,18 +948,21 @@ 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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for c in "नमˑे".chars() {
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println!("{}", c);
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let hello = "测试中文字符串";
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for c in hello.chars() {
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print!("{} ", c);
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}
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for b in "नमˑे".bytes() {
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println!("{}", b);
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println!("");
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for b in hello.bytes() {
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print!("{} ", b);
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}
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let hello = "Здравствуйте";
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let s = &hello[0..4];
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println!("&hello[0..4]={}", s);
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println!("");
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// let s = hello[1]; // Rust 的字符串不支持索引
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// 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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print!("{}", &hello[0..3]);
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}
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fn test_tuple(t: (i32, &str)) {
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@ -1265,9 +1268,9 @@ 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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@ -1335,18 +1338,18 @@ 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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@ -1406,10 +1409,10 @@ struct Shoe {
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fn shoes_in_my_size(shoes: Vec<Shoe>, shoe_size: u32) -> Vec<Shoe> {
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shoes
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// .iter() // a collection of type `std::vec::Vec<Shoe>` cannot be built from `std::iter::Iterator<Item=&Shoe>`
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.into_iter() //获取 vector 所有权的迭代器
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.filter(|s| s.size == shoe_size)
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.collect()
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// .iter() // a collection of type `std::vec::Vec<Shoe>` cannot be built from `std::iter::Iterator<Item=&Shoe>`
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.into_iter() //获取 vector 所有权的迭代器
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.filter(|s| s.size == shoe_size)
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.collect()
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}
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struct Counter {
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