pain

src/basic_search.rs

@@ -1,3 +1,5 @@
+#![allow(dead_code)]
+
 use std::collections::VecDeque;
 
 struct Node<T> {

src/lib.rs

@@ -1,27 +1,23 @@
 //! https://www.baeldung.com/java-monte-carlo-tree-search
 
-#![allow(dead_code)]
-
 mod basic_search;
 
+pub use mcts::find_next_move;
+
 pub trait GameState {
     fn points(&self) -> i32;
 
-    fn next(&self) -> &[Self]
-    where
-        Self: Sized;
+    fn next_states(&self) -> Box<dyn Iterator<Item = Self>>;
 
     fn is_finished(&self) -> bool;
 }
 
 mod mcts {
     use crate::GameState;
-    use bumpalo::collections::Vec;
+    use bumpalo::collections::Vec as BumpVec;
     use bumpalo::Bump;
     use rand::Rng;
-    use std::cell::{Cell, RefCell};
-
-    type Tree<'tree, S> = RefCell<Node<'tree, S>>;
+    use std::cell::Cell;
 
     #[derive(Clone)]
     struct Node<'tree, S> {
@@ -29,11 +25,9 @@ mod mcts {
         visited: Cell<u64>,
         score: Cell<u64>,
         parent: Option<&'tree Node<'tree, S>>,
-        children: Vec<'tree, Node<'tree, S>>,
+        children: BumpVec<'tree, Node<'tree, S>>,
     }
 
-    type RefNode<'tree, S> = RefCell<Node<'tree, S>>;
-
     impl<'tree, S> Node<'tree, S> {
         fn new(state: S, alloc: &'tree Bump) -> Node<S> {
             Node {
@@ -41,7 +35,7 @@ mod mcts {
                 visited: Cell::new(0),
                 score: Cell::new(0),
                 parent: None,
-                children: Vec::new_in(alloc),
+                children: BumpVec::new_in(alloc),
             }
         }
 
@@ -69,7 +63,7 @@ mod mcts {
             let promising_node = select_promising_node(root_node);
 
             if !promising_node.state.is_finished() {
-                expand_node(promising_node);
+                expand_node(&alloc, promising_node);
             }
 
             if !promising_node.children.is_empty() {
@@ -98,8 +92,26 @@ mod mcts {
         node
     }
 
-    fn expand_node<S>(_node: &Node<'_, S>) {
-        todo!("next")
+    fn expand_node<S: GameState>(alloc: &Bump, node: &Node<'_, S>) {
+        /*
+               List<State> possibleStates = node.getState().getAllPossibleStates();
+        possibleStates.forEach(state -> {
+            Node newNode = new Node(state);
+            newNode.setParent(node);
+            newNode.getState().setPlayerNo(node.getState().getOpponent());
+            node.getChildArray().add(newNode);
+        });
+             */
+        let possible_states = node.state.next_states();
+        for state in possible_states {
+            let child = Node {
+                state,
+                visited: Cell::new(0),
+                score: Cell::new(0),
+                parent: Some(node),
+                children: BumpVec::new_in(alloc),
+            };
+        }
     }
 
     fn simulate_random_playout<S>(_node: &Node<'_, S>) -> u64 {