feat: immediately return score of hash moves

2 files changed, 25 insertions, 9 deletions

diff --git a/src/board/engine.rs b/src/board/engine.rs
index c43a722..da0f38b 100644
--- a/src/board/engine.rs
+++ b/src/board/engine.rs
@@ -217,11 +217,12 @@ impl Board {
         0.0
     }
 
-    pub fn hash_move(&self) -> Option<Move> {
+    /// Find current transposition in Transposition Table
+    pub fn transposition(&self) -> Option<TranspositionTableItem> {
         match self.transposition_table[(self.hash % TTABLE_SIZE) as usize] {
             Some(item) => {
                 if item.hash == self.hash {
-                    return Some(item.best_move)
+                    return Some(item)
                 }
                 None
             }
@@ -267,8 +268,8 @@ impl Board {
 
         }
 
-        match self.hash_move() {
-            Some(mov) => ordered_moves.insert(0, mov),
+        match self.transposition() {
+            Some(transposition) => ordered_moves.insert(0, transposition.mov),
             None => {},
         }
 
@@ -280,6 +281,21 @@ impl Board {
         let mut killer_moves = Vec::new();
         let color = self.color();
 
+        match self.transposition() {
+            Some(transposition) => {
+                if transposition.depth >= depth_left {
+                    match transposition.node_type {
+                        NodeType::PV => { // PV-nodes have exact score
+                            principal_variation.push(transposition.mov);
+                            return (transposition.score, principal_variation);
+                        }
+                        _ => {} // TODO: prune when out ouf bounds
+                    }
+                }
+            }
+            None => {},
+        }
+
         let mut moves = self.generate_pseudolegal_moves(color);
         moves = self.order_moves(moves, parent_killers.to_vec());
 
@@ -319,7 +335,7 @@ impl Board {
                 if score >= beta {
                     self.transposition_table[(self.hash % TTABLE_SIZE) as usize] = Some(TranspositionTableItem {
                         hash: self.hash,
-                        best_move: mov,
+                        mov,
                         depth: depth_left, // TODO: should be actual depth searched
                         node_type: NodeType::Cut,
                         score,
@@ -343,7 +359,7 @@ impl Board {
 
                     self.transposition_table[(self.hash % TTABLE_SIZE) as usize] = Some(TranspositionTableItem {
                         hash: self.hash,
-                        best_move: mov,
+                        mov,
                         depth: depth_left, // TODO: should be actual depth searched
                         node_type: NodeType::PV,
                         score,
@@ -351,7 +367,7 @@ impl Board {
                 } else {
                     self.transposition_table[(self.hash % TTABLE_SIZE) as usize] = Some(TranspositionTableItem {
                         hash: self.hash,
-                        best_move: mov,
+                        mov,
                         depth: depth_left, // TODO: should be actual depth searched
                         node_type: NodeType::All,
                         score,
@@ -363,7 +379,7 @@ impl Board {
 
             // Could not finish in time, return what we have so far
             if Instant::now() > deadline {
-                return (alpha, principal_variation)
+                break;
             }
         }
 
diff --git a/src/board/ttable.rs b/src/board/ttable.rs
index 3a103da..9f9e0b0 100644
--- a/src/board/ttable.rs
+++ b/src/board/ttable.rs
@@ -15,7 +15,7 @@ pub enum NodeType {
 pub struct TranspositionTableItem {
     /// Zobrist hash of this position
     pub hash: u64,
-    pub best_move: Move,
+    pub mov: Move,
     pub depth: u8,
     pub score: f32,
     pub node_type: NodeType,