From 4dfc11d74ab02ac5765ae5d08fb750c91f4744b4 Mon Sep 17 00:00:00 2001 From: Hunter Kvalevog Date: Fri, 2 Oct 2026 21:53:51 -0500 Subject: rustlings: move to rust/ --- rustlings/exercises/19_smart_pointers/cow1.rs | 66 --------------------------- 1 file changed, 66 deletions(-) delete mode 100644 rustlings/exercises/19_smart_pointers/cow1.rs (limited to 'rustlings/exercises/19_smart_pointers/cow1.rs') 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(_))); - } -} -- cgit v1.2.3