91 lines
1.9 KiB
Rust
91 lines
1.9 KiB
Rust
use std::rc::Rc;
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#[derive(Debug)]
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enum List {
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Cons(i32, Rc<List>),
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Nil,
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}
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use std::ops::Deref;
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struct MyBox<T>(T);
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impl<T> MyBox<T> {
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fn new(x: T) -> MyBox<T> {
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MyBox(x)
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}
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}
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impl<T> Deref for MyBox<T> {
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type Target = T;
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fn deref(&self) -> &T {
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&self.0
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}
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}
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struct CustomSmartPointer {
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data: String,
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}
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impl Drop for CustomSmartPointer {
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fn drop(&mut self) {
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println!("Dropping CustomSmartPointer with data `{}`!", self.data);
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}
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}
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use crate::List::{Cons, Nil};
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fn hello(name: &str) {
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println!("Hello, {}!", name);
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}
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fn main() {
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let b = Box::new(5);
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println!("b = {}", b);
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let list = Cons(1, Rc::new(Cons(2, Rc::new(Cons(3, Rc::new(Nil))))));
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println!("{:?}", list);
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let x = 5;
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let y = MyBox::new(x);
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assert_eq!(5, x);
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assert_eq!(5, *y);
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let m = MyBox::new(String::from("Rust"));
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hello(&m);
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hello(&(*m)[..]);
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let c = CustomSmartPointer {
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data: String::from("my stuff"),
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};
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let d = CustomSmartPointer {
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data: String::from("other stuff"),
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};
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println!("CustomSmartPointers created.");
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println!("{}, {}", c.data, d.data);
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drop(c);
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println!("CustomSmartPointer dropped before the end of main.");
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let a = Rc::new(Cons(5, Rc::new(Cons(10, Rc::new(Nil)))));
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println!("count after creating a = {}", Rc::strong_count(&a));
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let b = Cons(3, Rc::clone(&a));
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println!("count after creating b = {}", Rc::strong_count(&a));
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{
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let _c = Cons(4, Rc::clone(&a));
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println!("count after creating c = {}", Rc::strong_count(&a));
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}
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match b {
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Cons(_aa, bb) => {
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match &*bb {
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Cons(cc, _dd) => println!("{}", cc),
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Nil => println!("Nil"),
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}
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}
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Nil => println!("Nil"),
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};
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println!("count after c goes out of scope = {}", Rc::strong_count(&a));
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} |