chay.dev
Going through rustlings for the first time
1// In this exercise, we want to express the concept of multiple owners via the
2// `Rc<T>` type. This is a model of our solar system - there is a `Sun` type and
3// multiple `Planet`s. The planets take ownership of the sun, indicating that
4// they revolve around the sun.
5
6use std::rc::Rc;
7
8#[derive(Debug)]
9struct Sun;
10
11#[derive(Debug)]
12enum Planet {
13 Mercury(Rc<Sun>),
14 Venus(Rc<Sun>),
15 Earth(Rc<Sun>),
16 Mars(Rc<Sun>),
17 Jupiter(Rc<Sun>),
18 Saturn(Rc<Sun>),
19 Uranus(Rc<Sun>),
20 Neptune(Rc<Sun>),
21}
22
23impl Planet {
24 fn details(&self) {
25 println!("Hi from {self:?}!");
26 }
27}
28
29fn main() {
30 // You can optionally experiment here.
31}
32
33#[cfg(test)]
34mod tests {
35 use super::*;
36
37 #[test]
38 fn rc1() {
39 let sun = Rc::new(Sun);
40 println!("reference count = {}", Rc::strong_count(&sun)); // 1 reference
41
42 let mercury = Planet::Mercury(Rc::clone(&sun));
43 println!("reference count = {}", Rc::strong_count(&sun)); // 2 references
44 mercury.details();
45
46 let venus = Planet::Venus(Rc::clone(&sun));
47 println!("reference count = {}", Rc::strong_count(&sun)); // 3 references
48 venus.details();
49
50 let earth = Planet::Earth(Rc::clone(&sun));
51 println!("reference count = {}", Rc::strong_count(&sun)); // 4 references
52 earth.details();
53
54 let mars = Planet::Mars(Rc::clone(&sun));
55 println!("reference count = {}", Rc::strong_count(&sun)); // 5 references
56 mars.details();
57
58 let jupiter = Planet::Jupiter(Rc::clone(&sun));
59 println!("reference count = {}", Rc::strong_count(&sun)); // 6 references
60 jupiter.details();
61
62 let saturn = Planet::Saturn(Rc::clone(&sun));
63 println!("reference count = {}", Rc::strong_count(&sun)); // 7 references
64 saturn.details();
65
66 // TODO
67 let uranus = Planet::Uranus(Rc::clone(&sun));
68 println!("reference count = {}", Rc::strong_count(&sun)); // 8 references
69 uranus.details();
70
71 // TODO
72 let neptune = Planet::Neptune(Rc::clone(&sun));
73 println!("reference count = {}", Rc::strong_count(&sun)); // 9 references
74 neptune.details();
75
76 assert_eq!(Rc::strong_count(&sun), 9);
77
78 drop(neptune);
79 println!("reference count = {}", Rc::strong_count(&sun)); // 8 references
80
81 drop(uranus);
82 println!("reference count = {}", Rc::strong_count(&sun)); // 7 references
83
84 drop(saturn);
85 println!("reference count = {}", Rc::strong_count(&sun)); // 6 references
86
87 drop(jupiter);
88 println!("reference count = {}", Rc::strong_count(&sun)); // 5 references
89
90 drop(mars);
91 println!("reference count = {}", Rc::strong_count(&sun)); // 4 references
92
93 drop(earth);
94 println!("reference count = {}", Rc::strong_count(&sun)); // 3 references
95
96 drop(venus);
97 println!("reference count = {}", Rc::strong_count(&sun)); // 2 references
98
99 drop(mercury);
100 println!("reference count = {}", Rc::strong_count(&sun)); // 1 reference
101
102 assert_eq!(Rc::strong_count(&sun), 1);
103 }
104}