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Map on the data within the node instead of the node itself

This commit is contained in:
Savanni D'Gerinel 2023-10-24 23:05:02 -04:00
parent 0fbfb4f1ad
commit c2e34db79c
1 changed files with 13 additions and 4 deletions
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17
tree/src/lib.rs
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@ -60,14 +60,23 @@ impl<T> Tree<T> {
None None
} }
/// Convert each node of a tree from type T to type U
pub fn map<F, U>(&self, op: F) -> Tree<U> pub fn map<F, U>(&self, op: F) -> Tree<U>
where where
F: FnOnce(&Node<T>) -> Node<U> + Copy, F: FnOnce(&T) -> U + Copy,
{ {
// A key part of this is to avoid recursion. There is no telling how deep a tree may go (Go
// game records can go hundreds of nodes deep), so we're going to just avoid recursion.
match self { match self {
Tree::Empty => Tree::Empty, Tree::Empty => Tree::Empty,
Tree::Root(root) => { Tree::Root(root) => {
let new_root = op(root); let new_root = Node::new(op(&root.value()));
// This queue serves as a work list. Each node in the queue needs to be converted,
// and I've paired the node up with the one that it's supposed to be attached to.
// So, as we look at a node A, we make sure that all of its children gets added to
// the queue, and that the queue knows that the conversion of each child node
// should get attached to A.
let mut queue: VecDeque<(Node<T>, Node<U>)> = root let mut queue: VecDeque<(Node<T>, Node<U>)> = root
.children() .children()
.iter() .iter()
@ -75,7 +84,7 @@ impl<T> Tree<T> {
.collect(); .collect();
while let Some((source, dest)) = queue.pop_front() { while let Some((source, dest)) = queue.pop_front() {
let res = op(&source); let res = Node::new(op(&source.value()));
dest.add_child_node(res.clone()); dest.add_child_node(res.clone());
for child in source.children().iter() { for child in source.children().iter() {
@ -174,7 +183,7 @@ mod tests {
let n = n.add_child_value(16); let n = n.add_child_value(16);
let _ = n.add_child_value(17); let _ = n.add_child_value(17);
let tree2 = tree.map(|v| Node::new(v.value().to_string())); let tree2 = tree.map(|v| v.to_string());
assert!(tree2.find_bfs(|val| *val == "15").is_some()); assert!(tree2.find_bfs(|val| *val == "15").is_some());
assert!(tree2.find_bfs(|val| *val == "16").is_some()); assert!(tree2.find_bfs(|val| *val == "16").is_some());