100 lines
2.9 KiB
Rust
100 lines
2.9 KiB
Rust
// rc1.rs
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// In this exercise, we want to express the concept of multiple owners via the Rc<T> type.
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// This is a model of our solar system - there is a Sun type and multiple Planets.
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// The Planets take ownership of the sun, indicating that they revolve around the sun.
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// Make this code compile by using the proper Rc primitives to express that the sun has multiple owners.
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// I AM NOT DONE
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use std::rc::Rc;
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#[derive(Debug)]
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struct Sun {}
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#[derive(Debug)]
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enum Planet {
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Mercury(Rc<Sun>),
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Venus(Rc<Sun>),
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Earth(Rc<Sun>),
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Mars(Rc<Sun>),
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Jupiter(Rc<Sun>),
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Saturn(Rc<Sun>),
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Uranus(Rc<Sun>),
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Neptune(Rc<Sun>),
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}
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impl Planet {
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fn details(&self) {
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println!("Hi from {:?}!", self)
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}
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}
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fn main() {
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let sun = Rc::new(Sun {});
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println!("reference count = {}", Rc::strong_count(&sun)); // 1 reference
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let mercury = Planet::Mercury(Rc::clone(&sun));
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println!("reference count = {}", Rc::strong_count(&sun)); // 2 references
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mercury.details();
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let venus = Planet::Venus(Rc::clone(&sun));
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println!("reference count = {}", Rc::strong_count(&sun)); // 3 references
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venus.details();
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let earth = Planet::Earth(Rc::clone(&sun));
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println!("reference count = {}", Rc::strong_count(&sun)); // 4 references
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earth.details();
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let mars = Planet::Mars(Rc::clone(&sun));
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println!("reference count = {}", Rc::strong_count(&sun)); // 5 references
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mars.details();
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let jupiter = Planet::Jupiter(Rc::clone(&sun));
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println!("reference count = {}", Rc::strong_count(&sun)); // 6 references
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jupiter.details();
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// TODO
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let saturn = Planet::Saturn(Rc::new(Sun {}));
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println!("reference count = {}", Rc::strong_count(&sun)); // 7 references
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saturn.details();
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// TODO
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let uranus = Planet::Uranus(Rc::new(Sun {}));
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println!("reference count = {}", Rc::strong_count(&sun)); // 8 references
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uranus.details();
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// TODO
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let neptune = Planet::Neptune(Rc::new(Sun {}));
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println!("reference count = {}", Rc::strong_count(&sun)); // 9 references
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neptune.details();
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assert_eq!(Rc::strong_count(&sun), 9);
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drop(neptune);
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println!("reference count = {}", Rc::strong_count(&sun)); // 8 references
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drop(uranus);
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println!("reference count = {}", Rc::strong_count(&sun)); // 7 references
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drop(saturn);
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println!("reference count = {}", Rc::strong_count(&sun)); // 6 references
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drop(jupiter);
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println!("reference count = {}", Rc::strong_count(&sun)); // 5 references
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drop(mars);
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println!("reference count = {}", Rc::strong_count(&sun)); // 4 references
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// TODO
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println!("reference count = {}", Rc::strong_count(&sun)); // 3 references
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// TODO
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println!("reference count = {}", Rc::strong_count(&sun)); // 2 references
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// TODO
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println!("reference count = {}", Rc::strong_count(&sun)); // 1 reference
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assert_eq!(Rc::strong_count(&sun), 1);
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}
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