Linked lists for fun in Rust

Nov 10, 2023

I did a leetcode question in Rust for fun and thought I'd implement a reversal method for their linked list implementation while trying to borrow as much as I can.

struct Node<'a, T> {
    value: &'a T,
    next: Option<Box<Node<'a, T>>>,
}

impl<'a, T> Node<'a, T> {
    fn reversed(&self) -> Self {
        fn inner<'a, T>(node: &Node<'a, T>, acc: Option<Box<Node<'a, T>>>) -> Node<'a, T> {
            let x = &node.next;
            let xs = Node {
                value: node.value,
                next: acc,
            };
            // x.map_or(xs, |node| inner(node, Some(Box::new(xs)))); // XXX: does not work because the closure is set up to take ownership of the node.
            match x {
                Some(node) => inner(node, Some(Box::new(xs))),
                None => xs,
            }
        }
        inner(self, None)
    }
}