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-rw-r--r--exercises/19_smart_pointers/box1.rs42
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());
}
}