diff options
| author | Hunter Kvalevog <hunter@kvog.sh> | 2026-10-02 21:53:51 -0500 |
|---|---|---|
| committer | Hunter Kvalevog <hunter@kvog.sh> | 2026-10-02 21:53:51 -0500 |
| commit | 4dfc11d74ab02ac5765ae5d08fb750c91f4744b4 (patch) | |
| tree | 17ba62056d6b691dd0217b0e8f1b3a5826dce0f6 /rustlings/exercises/19_smart_pointers | |
| parent | 02d8f1c62896576e1266553a56980eddbc2a88d7 (diff) | |
rustlings: move to rust/
Diffstat (limited to 'rustlings/exercises/19_smart_pointers')
| -rw-r--r-- | rustlings/exercises/19_smart_pointers/README.md | 12 | ||||
| -rw-r--r-- | rustlings/exercises/19_smart_pointers/arc1.rs | 45 | ||||
| -rw-r--r-- | rustlings/exercises/19_smart_pointers/box1.rs | 50 | ||||
| -rw-r--r-- | rustlings/exercises/19_smart_pointers/cow1.rs | 66 | ||||
| -rw-r--r-- | rustlings/exercises/19_smart_pointers/rc1.rs | 108 |
5 files changed, 0 insertions, 281 deletions
diff --git a/rustlings/exercises/19_smart_pointers/README.md b/rustlings/exercises/19_smart_pointers/README.md deleted file mode 100644 index d56d2b6..0000000 --- a/rustlings/exercises/19_smart_pointers/README.md +++ /dev/null @@ -1,12 +0,0 @@ -# Smart Pointers - -In Rust, smart pointers are variables that contain an address in memory and reference some other data, but they also have additional metadata and capabilities. -Smart pointers in Rust often own the data they point to, while references only borrow data. - -## Further Information - -- [Smart Pointers](https://doc.rust-lang.org/book/ch15-00-smart-pointers.html) -- [Using Box to Point to Data on the Heap](https://doc.rust-lang.org/book/ch15-01-box.html) -- [Rc\<T\>, the Reference Counted Smart Pointer](https://doc.rust-lang.org/book/ch15-04-rc.html) -- [Shared-State Concurrency](https://doc.rust-lang.org/book/ch16-03-shared-state.html) -- [Cow Documentation](https://doc.rust-lang.org/std/borrow/enum.Cow.html) diff --git a/rustlings/exercises/19_smart_pointers/arc1.rs b/rustlings/exercises/19_smart_pointers/arc1.rs deleted file mode 100644 index f44e4e1..0000000 --- a/rustlings/exercises/19_smart_pointers/arc1.rs +++ /dev/null @@ -1,45 +0,0 @@ -// In this exercise, we are given a `Vec` of `u32` called `numbers` with values -// ranging from 0 to 99. We would like to use this set of numbers within 8 -// different threads simultaneously. Each thread is going to get the sum of -// every eighth value with an offset. -// -// The first thread (offset 0), will sum 0, 8, 16, … -// The second thread (offset 1), will sum 1, 9, 17, … -// The third thread (offset 2), will sum 2, 10, 18, … -// … -// The eighth thread (offset 7), will sum 7, 15, 23, … -// -// Each thread should own a reference-counting pointer to the vector of -// numbers. But `Rc` isn't thread-safe. Therefore, we need to use `Arc`. -// -// Don't get distracted by how threads are spawned and joined. We will practice -// that later in the exercises about threads. - -// Don't change the lines below. -#![forbid(unused_imports)] -use std::{sync::Arc, thread}; - -fn main() { - let numbers: Vec<_> = (0..100u32).collect(); - - // TODO: Define `shared_numbers` by using `Arc`. - let shared_numbers = Arc::new(numbers); - - let mut join_handles = Vec::new(); - - for offset in 0..8 { - // TODO: Define `child_numbers` using `shared_numbers`. - let child_numbers = shared_numbers.clone(); - - let handle = thread::spawn(move || { - let sum: u32 = child_numbers.iter().filter(|&&n| n % 8 == offset).sum(); - println!("Sum of offset {offset} is {sum}"); - }); - - join_handles.push(handle); - } - - for handle in join_handles.into_iter() { - handle.join().unwrap(); - } -} diff --git a/rustlings/exercises/19_smart_pointers/box1.rs b/rustlings/exercises/19_smart_pointers/box1.rs deleted file mode 100644 index ee379ca..0000000 --- a/rustlings/exercises/19_smart_pointers/box1.rs +++ /dev/null @@ -1,50 +0,0 @@ -// At compile time, Rust needs to know how much space a type takes up. This -// becomes problematic for recursive types, where a value can have as part of -// itself another value of the same type. To get around the issue, we can use a -// `Box` - a smart pointer used to store data on the heap, which also allows us -// to wrap a recursive type. -// -// The recursive type we're implementing in this exercise is the "cons list", a -// data structure frequently found in functional programming languages. Each -// item in a cons list contains two elements: The value of the current item and -// the next item. The last item is a value called `Nil`. - -// TODO: Use a `Box` in the enum definition to make the code compile. -#[derive(PartialEq, Debug)] -enum List { - Cons(i32, Box<List>), - Nil, -} - -// TODO: Create an empty cons list. -fn create_empty_list() -> List { - List::Nil -} - -// TODO: Create a non-empty cons list. -fn create_non_empty_list() -> List { - List::Cons(1, Box::new(List::Nil)) -} - -fn main() { - println!("This is an empty cons list: {:?}", create_empty_list()); - println!( - "This is a non-empty cons list: {:?}", - create_non_empty_list(), - ); -} - -#[cfg(test)] -mod tests { - use super::*; - - #[test] - fn test_create_empty_list() { - assert_eq!(create_empty_list(), List::Nil); - } - - #[test] - fn test_create_non_empty_list() { - assert_ne!(create_empty_list(), create_non_empty_list()); - } -} diff --git a/rustlings/exercises/19_smart_pointers/cow1.rs b/rustlings/exercises/19_smart_pointers/cow1.rs deleted file mode 100644 index 56a25b9..0000000 --- a/rustlings/exercises/19_smart_pointers/cow1.rs +++ /dev/null @@ -1,66 +0,0 @@ -// This exercise explores the `Cow` (Clone-On-Write) smart pointer. It can -// enclose and provide immutable access to borrowed data and clone the data -// lazily when mutation or ownership is required. The type is designed to work -// with general borrowed data via the `Borrow` trait. - -use std::borrow::Cow; - -fn abs_all(input: &mut Cow<[i32]>) { - for ind in 0..input.len() { - let value = input[ind]; - if value < 0 { - // Clones into a vector if not already owned. - input.to_mut()[ind] = -value; - } - } -} - -fn main() { - // You can optionally experiment here. -} - -#[cfg(test)] -mod tests { - use super::*; - - #[test] - fn reference_mutation() { - // Clone occurs because `input` needs to be mutated. - let vec = vec![-1, 0, 1]; - let mut input = Cow::from(&vec); - abs_all(&mut input); - assert!(matches!(input, Cow::Owned(_))); - } - - #[test] - fn reference_no_mutation() { - // No clone occurs because `input` doesn't need to be mutated. - let vec = vec![0, 1, 2]; - let mut input = Cow::from(&vec); - abs_all(&mut input); - assert!(matches!(input, Cow::Borrowed(_))); - } - - #[test] - fn owned_no_mutation() { - // We can also pass `vec` without `&` so `Cow` owns it directly. In this - // case, no mutation occurs (all numbers are already absolute) and thus - // also no clone. But the result is still owned because it was never - // borrowed or mutated. - let vec = vec![0, 1, 2]; - let mut input = Cow::from(vec); - abs_all(&mut input); - assert!(matches!(input, Cow::Owned(_))); - } - - #[test] - fn owned_mutation() { - // Of course this is also the case if a mutation does occur (not all - // numbers are absolute). In this case, the call to `to_mut()` in the - // `abs_all` function returns a reference to the same data as before. - let vec = vec![-1, 0, 1]; - let mut input = Cow::from(vec); - abs_all(&mut input); - assert!(matches!(input, Cow::Owned(_))); - } -} diff --git a/rustlings/exercises/19_smart_pointers/rc1.rs b/rustlings/exercises/19_smart_pointers/rc1.rs deleted file mode 100644 index 5c9ce84..0000000 --- a/rustlings/exercises/19_smart_pointers/rc1.rs +++ /dev/null @@ -1,108 +0,0 @@ -// 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 `Planet`s. The planets take ownership of the sun, indicating that -// they revolve around the sun. - -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() { - // You can optionally experiment here. -} - -#[cfg(test)] -mod tests { - use super::*; - - #[test] - fn rc1() { - 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::clone(&sun)); - println!("reference count = {}", Rc::strong_count(&sun)); // 7 references - saturn.details(); - - // TODO - let uranus = Planet::Uranus(Rc::clone(&sun)); - println!("reference count = {}", Rc::strong_count(&sun)); // 8 references - uranus.details(); - - // TODO - let neptune = Planet::Neptune(Rc::clone(&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 - drop(earth); - println!("reference count = {}", Rc::strong_count(&sun)); // 3 references - - // TODO - drop(venus); - println!("reference count = {}", Rc::strong_count(&sun)); // 2 references - - // TODO - drop(mercury); - println!("reference count = {}", Rc::strong_count(&sun)); // 1 reference - - assert_eq!(Rc::strong_count(&sun), 1); - } -} |