How to Implement the Visitor Pattern in Rust

Implement the Visitor Pattern in Rust by defining a Visitor trait with methods for each node type and a visit method on your data structure that dispatches to the trait.

trait Visitor {
    fn visit_node(&self, node: &Node) {}
}

enum Node {
    Leaf(i32),
    Branch(Vec<Node>),
}

impl Node {
    fn visit<V: Visitor>(&self, v: &V) {
        match self {
            Node::Leaf(_) => v.visit_node(self),
            Node::Branch(children) => {
                for child in children {
                    child.visit(v);
                }
            }
        }
    }
}

The Visitor Pattern lets you add new operations to a set of objects without changing their code. It works by separating the algorithm from the object structure, like a tour guide visiting different rooms in a house to perform specific tasks without altering the house itself. You use this when you need to perform complex actions on a tree-like data structure without cluttering the node definitions.