quizzes

practice/src/bin/m_node.rs

@@ -0,0 +1,45 @@
+use std::cell::RefCell;
+use std::rc::{Rc, Weak};
+
+#[derive(Debug)]
+struct Node {
+    value: i32,
+    parent: RefCell<Option<Weak<Node>>>,                            // <-- weak ref to parent
+    children: RefCell<Vec<Rc<Node>>>,
+}
+
+impl Node {
+    fn new(value: i32) -> Rc<Self> {
+        Rc::new(Self {
+            value,
+            parent: Default::default(),
+            children: Default::default(),
+        })
+    }
+
+    fn set_parent(&self, parent: Rc<Node>) {
+        *self.parent.borrow_mut() = Some(Rc::downgrade(&parent));   // <-- create weak ref to parent
+    }
+
+    fn add_child(self: &Rc<Self>, child: Rc<Node>) {
+        child.set_parent(self.clone());
+        self.children.borrow_mut().push(child);
+    }
+}
+
+impl Drop for Node {
+    fn drop(&mut self) {
+        println!(
+            "Dropping node with value {} and {} children",
+            self.value,
+            self.children.borrow().len()
+        );
+    }
+}
+
+fn main() {
+    let tree = Node::new(1);
+    tree.add_child(Node::new(3));
+    tree.add_child(Node::new(5));
+    println!("Finishing program now");
+}