Build a basic tree and experiment with traversals

Cargo.lock

@@ -4060,6 +4060,10 @@ version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "efd1f82c56340fdf16f2a953d7bda4f8fdffba13d93b00844c25572110b26079"
 
+[[package]]
+name = "tree"
+version = "0.1.0"
+
 [[package]]
 name = "try-lock"
 version = "0.2.4"

Cargo.toml

@@ -20,4 +20,5 @@ members = [
     "result-extended",
     "screenplay",
     "sgf",
+    "tree",
 ]

build.sh

@@ -23,6 +23,7 @@ RUST_ALL_TARGETS=(
     "result-extended"
     "screenplay"
     "sgf"
+    "tree"
 )
 
 build_rust_targets() {

tree/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "tree"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

tree/src/lib.rs

@@ -0,0 +1,113 @@
+//! This data structure is a generic tree which can contain any data. That data itself need to keep
+//! track of its own tree structure.
+//!
+//! This surely already exists. I am created it to test my own ability to do things in Rust.
+
+use std::{cell::RefCell, collections::VecDeque, rc::Rc};
+
+#[derive(Debug)]
+pub enum Tree<T> {
+    Empty,
+    Root(Rc<RefCell<Node<T>>>),
+}
+
+impl<T> Default for Tree<T> {
+    fn default() -> Self {
+        Tree::Empty
+    }
+}
+
+impl<T> Tree<T> {
+    pub fn set_value(&mut self, value: T) {
+        *self = Tree::Root(Rc::new(RefCell::new(Node::new(value))));
+    }
+
+    pub fn find_bfs<'a, F>(&'a self, op: F) -> Option<Rc<RefCell<Node<T>>>>
+    where
+        F: FnOnce(&T) -> bool + Copy,
+    {
+        let mut queue: VecDeque<Rc<RefCell<Node<T>>>> = match self {
+            Tree::Empty => VecDeque::new(),
+            Tree::Root(node) => {
+                let mut queue = VecDeque::new();
+                queue.push_back(node.clone());
+                queue
+            }
+        };
+
+        while let Some(node) = queue.pop_front() {
+            if op(&node.borrow().value) {
+                return Some(node.clone());
+            }
+
+            for child in node.borrow().children.iter() {
+                queue.push_back(child.clone());
+            }
+        }
+        None
+    }
+}
+
+#[derive(Debug, PartialEq)]
+pub struct Node<T> {
+    value: T,
+    children: Vec<Rc<RefCell<Node<T>>>>,
+}
+
+impl<T> Node<T> {
+    pub fn new(value: T) -> Self {
+        Self {
+            value,
+            children: vec![],
+        }
+    }
+
+    pub fn children<'a>(&'a self) -> &'a Vec<Rc<RefCell<Node<T>>>> {
+        &self.children
+    }
+
+    pub fn value<'a>(&'a self) -> &'a T {
+        &self.value
+    }
+
+    pub fn value_mut<'a>(&'a mut self) -> &'a mut T {
+        &mut self.value
+    }
+
+    pub fn add_child_node(&mut self, child: Node<T>) {
+        self.children.push(Rc::new(RefCell::new(child)));
+    }
+
+    pub fn add_child_value(&mut self, value: T) {
+        self.children.push(Rc::new(RefCell::new(Node::new(value))));
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn can_find_node_in_tree() {
+        let mut tree = Tree::default();
+        tree.set_value(15);
+        assert!(tree.find_bfs(|val| *val == 15).is_some());
+        assert!(tree.find_bfs(|val| *val == 16).is_none());
+
+        {
+            let node_ref = tree.find_bfs(|val| *val == 15).unwrap();
+            node_ref.borrow_mut().add_child_value(20);
+        }
+
+        assert!(tree.find_bfs(|val| *val == 20).is_some());
+    }
+
+    #[test]
+    fn node_can_add_children() {
+        let mut n = Node::new(15);
+        n.add_child_value(20);
+
+        assert_eq!(n.value, 15);
+        assert_eq!(n.children, vec![Rc::new(RefCell::new(Node::new(20)))]);
+    }
+}