feat: improved scoring for (semi)dead positions

1 files changed, 21 insertions, 0 deletions

diff --git a/src/board/mod.rs b/src/board/mod.rs
index 1e4fd93..01a5b03 100644
--- a/src/board/mod.rs
+++ b/src/board/mod.rs
@@ -392,6 +392,27 @@ impl Board {
     pub fn threefold_repetition(&self) -> bool {
         self.positions.iter().filter(|&&p| p == self.hash).count() >= 3
     }
+
+    pub fn is_theoretically_winnable(&self, color: Color) -> bool {
+        if [
+            Piece::Pawn,
+            Piece::Rook,
+            Piece::Queen,
+        ].iter().any(|&piece| {
+            self.piece_sets[piece.colored(color) as usize].pop_count() > 0
+        }) {
+            return true;
+        };
+
+        let minor_pieces = [
+            Piece::Knight,
+            Piece::Bishop,
+        ].iter().fold(0, |acc, &piece| {
+            acc + self.piece_sets[piece.colored(color) as usize].pop_count()
+        });
+
+        minor_pieces > 1
+    }
 }