change handling of current_depth

src/logic/future_moves.rs

@@ -24,9 +24,6 @@ pub struct FutureMoves {
     /// Index of the [`Move`] tree's root node
     current_root: Option<usize>,
 
-    /// Current generated depth of the Arena
-    current_depth: usize,
-
     /// Color w.r.t
     agent_color: Piece,
 
@@ -110,7 +107,6 @@ impl FutureMoves {
         Self {
             arena: Vec::new(),
             current_root: None,
-            current_depth: 0,
             agent_color,
             config,
             board: Board::new(),
@@ -139,30 +135,27 @@ impl FutureMoves {
         indexes
     }
 
-    /// Find the current depth of the arena by
+    /// Return the current depth of the tree
-    /// looking at leaf moves and finding the smallest value
+    fn current_depth(&self) -> usize {
-    fn determine_current_depth(&self) -> Option<usize> {
         // leaf_moves is sorted from min to max depth
-        self.leaf_moves().first().map(|&i| self.depth_of(i))
+        self.leaf_moves()
+            .first()
+            .map(|&i| self.depth_of(i))
+            .unwrap_or(0) // handle empty trees
     }
 
     /// Generate children for all children of `nodes`
     /// only `pub` for the sake of benchmarking
     pub fn extend_layers(&mut self) {
-        // recover from partial tree extention
-        if let Some(current_depth) = self.determine_current_depth() {
-            self.current_depth = current_depth;
-        }
-
         let mut leafs = self.leaf_moves().into_iter().collect::<Vec<usize>>();
 
-        for _ in self.current_depth..self.config.max_depth {
+        for _ in self.current_depth()..self.config.max_depth {
             let pstyle_inner = if cfg!(test) || !self.config.print {
                 ""
             } else {
                 &format!(
                     "Generating children (depth: {}/{}): ({{pos}}/{{len}}) {{per_sec}}",
-                    self.current_depth + 1,
+                    self.current_depth() + 1,
                     self.config.max_depth
                 )
             };
@@ -197,7 +190,6 @@ impl FutureMoves {
             let got_len = curr_size.load(Ordering::Acquire);
 
             self.prune_bad_children();
-            self.current_depth += 1;
             if got_len == allowed_size {
                 // arena has hit the upper limit of size permitted
                 break;
@@ -430,7 +422,6 @@ impl FutureMoves {
     fn rebuild_from_board(&mut self, board: Board) {
         self.arena = vec![self.create_move(None, board, !self.agent_color)];
         self.current_root = Some(0);
-        self.current_depth = 0;
         self.board = board;
     }
 
@@ -438,7 +429,6 @@ impl FutureMoves {
         let board = self
             .get_board_from_idx(idx)
             .expect("unable to get board at idx");
-        self.current_depth -= self.depth_of(idx);
         self.current_root = Some(idx);
         self.board = board;
         self.refocus_tree();
@@ -490,7 +480,7 @@ impl FutureMoves {
     }
 
     fn prune_bad_children(&mut self) {
-        if self.current_depth < self.config.min_arena_depth || !self.config.do_prune {
+        if self.current_depth() < self.config.min_arena_depth || !self.config.do_prune {
             return;
         }
 
@@ -499,7 +489,7 @@ impl FutureMoves {
 
         for (depth, indexes) in self.by_depth(0..self.arena.len()) {
             // TODO! maybe update by_depth every iteration or something?
-            if depth > self.current_depth.saturating_sub(self.config.up_to_minus) {
+            if depth > self.current_depth().saturating_sub(self.config.up_to_minus) {
                 return;
             }