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