Apply material counting to stalemate (#973)

Author: ianfab

src/ffishjs.cpp

@@ -313,13 +313,8 @@ class Board {
 
     if (!gameEnd)
       return "*";
-    if (result == 0) {
-      if (pos.material_counting())
-        result = pos.material_counting_result();
-
-      if (result == 0)
-        return "1/2-1/2";
-    }
+    if (result == 0)
+      return "1/2-1/2";
     if (pos.side_to_move() == BLACK)
       result = -result;
     if (result > 0)

src/position.h

@@ -915,11 +915,6 @@ inline EnclosingRule Position::flip_enclosed_pieces() const {
 
 inline Value Position::stalemate_value(int ply) const {
   assert(var != nullptr);
-  if (var->stalematePieceCount)
-  {
-      int c = count<ALL_PIECES>(sideToMove) - count<ALL_PIECES>(~sideToMove);
-      return c == 0 ? VALUE_DRAW : convert_mate_value(c < 0 ? var->stalemateValue : -var->stalemateValue, ply);
-  }
   // Check for checkmate of pseudo-royal pieces
   if (var->extinctionPseudoRoyal)
   {
@@ -949,7 +944,17 @@ inline Value Position::stalemate_value(int ply) const {
               return convert_mate_value(var->checkmateValue, ply);
       }
   }
-  return convert_mate_value(var->stalemateValue, ply);
+  Value result = var->stalemateValue;
+  // Is piece count used to determine stalemate result?
+  if (var->stalematePieceCount)
+  {
+      int c = count<ALL_PIECES>(sideToMove) - count<ALL_PIECES>(~sideToMove);
+      result = c == 0 ? VALUE_DRAW : c < 0 ? var->stalemateValue : -var->stalemateValue;
+  }
+  // Apply material counting
+  if (result == VALUE_DRAW && var->materialCounting)
+      result = material_counting_result();
+  return convert_mate_value(result, ply);
 }
 
 inline Value Position::checkmate_value(int ply) const {

test.py

@@ -1082,6 +1082,17 @@ def test_game_result(self):
         result = sf.game_result("suicide", "8/8/8/7p/7P/8/8/n7 w - - 0 1", [])
         self.assertEqual(result, sf.VALUE_MATE)
 
+        # armageddon
+        # black gets stalemated
+        result = sf.game_result("armageddon", "k7/P7/K7/8/8/8/8/8 b - - 0 1", [])
+        self.assertEqual(result, sf.VALUE_MATE)
+        # white gets stalemated
+        result = sf.game_result("armageddon", "8/8/8/8/8/k7/p7/K7 w - - 0 1", [])
+        self.assertEqual(result, -sf.VALUE_MATE)
+        # 50 move rule
+        result = sf.game_result("armageddon", "3n4/8/8/3k4/8/3K4/8/3BB3 w - - 100 80", [])
+        self.assertEqual(result, -sf.VALUE_MATE)
+
         # atomic check- and stalemate
         # checkmate
         result = sf.game_result("atomic", "BQ6/Rk6/8/8/8/8/8/4K3 b - - 0 1", [])

tests/js/test.js

@@ -443,15 +443,9 @@ describe('board.result()', function () {
     board.pushSan("Kxd8");
     chai.expect(board.result()).to.equal("1/2-1/2");
 
-    // Insufficient material with material counting - black draw odds (armageddon)
+    // Stalemate with material counting - black draw odds (armageddon)
     board.delete();
     board = new ffish.Board("armageddon");
-    board.setFen("3Rk3/8/8/8/8/8/2N5/3K4 b - - 0 1");
-    chai.expect(board.result()).to.equal("*");
-    board.pushSan("Kxd8");
-    chai.expect(board.result()).to.equal("0-1");
-
-    // Stalemate with material counting - black draw odds (armageddon)
     board.setFen("2Q2bnr/4p1pq/5pkr/7p/7P/4P3/PPPP1PP1/RNB1KBNR w KQ - 1 10");
     chai.expect(board.result()).to.equal("*");
     board.pushSan("Qe6");