diff options
Diffstat (limited to 'exercises/19_smart_pointers/box1.rs')
| -rw-r--r-- | exercises/19_smart_pointers/box1.rs | 42 |
1 files changed, 17 insertions, 25 deletions
diff --git a/exercises/19_smart_pointers/box1.rs b/exercises/19_smart_pointers/box1.rs index 513e7da..d70e1c3 100644 --- a/exercises/19_smart_pointers/box1.rs +++ b/exercises/19_smart_pointers/box1.rs @@ -1,45 +1,37 @@ -// box1.rs -// // 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 +// 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 +// 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`. -// -// Step 1: use a `Box` in the enum definition to make the code compile -// Step 2: create both empty and non-empty cons lists by replacing `todo!()` -// -// Note: the tests should not be changed -// -// Execute `rustlings hint box1` or use the `hint` watch subcommand for a hint. - -// I AM NOT DONE +// TODO: Use a `Box` in the enum definition to make the code compile. #[derive(PartialEq, Debug)] -pub enum List { +enum List { Cons(i32, 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() - ); +// TODO: Create an empty cons list. +fn create_empty_list() -> List { + todo!() } -pub fn create_empty_list() -> List { +// TODO: Create a non-empty cons list. +fn create_non_empty_list() -> List { todo!() } -pub fn create_non_empty_list() -> List { - todo!() +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)] @@ -48,11 +40,11 @@ mod tests { #[test] fn test_create_empty_list() { - assert_eq!(List::Nil, 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()) + assert_ne!(create_empty_list(), create_non_empty_list()); } } |
