chess: don't store capture piece in Move

e0ff · Nov 27, 2023 · f27e2e2 · f27e2e2
1 parent 14d0db6
commit f27e2e2
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Showing 3 changed files with 18 additions and 44 deletions.
diff --git a/internal/chess/move.go b/internal/chess/move.go
@@ -47,7 +47,6 @@ type Move struct {
 	flags    MoveFlag
 
 	promotionPiece Piece
-	capturePiece   Piece
 }
 
 var NullMove = NewMove(A1, A1, Null, NoMoveFlag)
@@ -60,7 +59,6 @@ func NewMove(from, to Square, moveType MoveType, flags MoveFlag) Move {
 		moveType:       moveType,
 		flags:          flags,
 		promotionPiece: EmptyPiece,
-		capturePiece:   EmptyPiece,
 	}
 }
 
@@ -80,12 +78,6 @@ func (m *Move) WithPromotion(piece Piece) {
 	m.promotionPiece = piece
 }
 
-// WithCapture sets that the move will result in the given piece being captured.
-func (m *Move) WithCapture(piece Piece) {
-	m.flags |= CaputureMoveFlag
-	m.capturePiece = piece
-}
-
 // Type returns the type of the move.
 func (m Move) Type() MoveType {
 	return m.moveType
@@ -117,9 +109,9 @@ func (m Move) IsPromotion() bool {
 	return m.promotionPiece != EmptyPiece
 }
 
-// Captures returns whether the move results in a capture.
-func (m Move) Captures() bool {
-	return m.capturePiece != EmptyPiece
+// IsCapture returns whether the move results in a capture.
+func (m Move) IsCapture() bool {
+	return m.HasFlag(CaputureMoveFlag)
 }
 
 // HasFlag checks if the move has that flag set.

diff --git a/internal/chess/movegen.go b/internal/chess/movegen.go
@@ -54,14 +54,12 @@ func generatePawnMoves(position Position, genType MoveGenerationType) []Move {
 			if capturePiece != EmptyPiece && capturePiece.Color() != position.turn {
 				if captureSquare.Rank() == pawnPromotionRank(position.Turn()) {
 					for _, pieceType := range promotablePieces {
-						move := NewMove(square, captureSquare, NormalMove, NoMoveFlag)
-						move.WithCapture(capturePiece)
+						move := NewMove(square, captureSquare, NormalMove, CaputureMoveFlag)
 						move.WithPromotion(NewPiece(pieceType, position.Turn()))
 						moves = append(moves, move)
 					}
 				} else {
-					move := NewMove(square, captureSquare, NormalMove, NoMoveFlag)
-					move.WithCapture(capturePiece)
+					move := NewMove(square, captureSquare, NormalMove, CaputureMoveFlag)
 					moves = append(moves, move)
 				}
 			}
@@ -73,8 +71,7 @@ func generatePawnMoves(position Position, genType MoveGenerationType) []Move {
 
 			capturePiece, _ := position.GetPieceAt(captureSquare)
 			if capturePiece.Type() == Pawn && capturePiece.Color() == position.Turn().OpposingSide() {
-				move := NewMove(square, position.EnPassant(), EnPassantMove, NoMoveFlag)
-				move.WithCapture(capturePiece)
+				move := NewMove(square, position.EnPassant(), EnPassantMove, CaputureMoveFlag)
 				moves = append(moves, move)
 			}
 		}
@@ -108,11 +105,7 @@ func generateKnightMoves(position Position, genType MoveGenerationType) []Move {
 		capturesBB := attackBB & opponent
 		for capturesBB > 0 {
 			toSquare := Square(capturesBB.PopLsb())
-			piece, _ := position.GetPieceAt(toSquare)
-
-			move := NewMove(fromSquare, toSquare, NormalMove, NoMoveFlag)
-			move.WithCapture(piece)
-
+			move := NewMove(fromSquare, toSquare, NormalMove, CaputureMoveFlag)
 			moves = append(moves, move)
 		}
 	}
@@ -143,11 +136,7 @@ func generateBishopMoves(position Position, pieceBB BitBoard, genType MoveGenera
 		capturesBB := attackBB & opponent
 		for capturesBB > 0 {
 			toSquare := Square(capturesBB.PopLsb())
-			piece, _ := position.GetPieceAt(toSquare)
-
-			move := NewMove(fromSquare, toSquare, NormalMove, NoMoveFlag)
-			move.WithCapture(piece)
-
+			move := NewMove(fromSquare, toSquare, NormalMove, CaputureMoveFlag)
 			moves = append(moves, move)
 		}
 	}
@@ -178,11 +167,7 @@ func generateRookMoves(position Position, pieceBB BitBoard, genType MoveGenerati
 		capturesBB := attacks & opponent
 		for capturesBB > 0 {
 			toSquare := Square(capturesBB.PopLsb())
-			piece, _ := position.GetPieceAt(toSquare)
-
-			move := NewMove(fromSquare, toSquare, NormalMove, NoMoveFlag)
-			move.WithCapture(piece)
-
+			move := NewMove(fromSquare, toSquare, NormalMove, CaputureMoveFlag)
 			moves = append(moves, move)
 		}
 	}
@@ -224,11 +209,7 @@ func generateKingMoves(position Position, genType MoveGenerationType, includeCas
 	capturesBB := attacks & opponent
 	for capturesBB > 0 {
 		toSquare := Square(capturesBB.PopLsb())
-		piece, _ := position.GetPieceAt(toSquare)
-
-		move := NewMove(kingSquare, toSquare, NormalMove, NoMoveFlag)
-		move.WithCapture(piece)
-
+		move := NewMove(kingSquare, toSquare, NormalMove, CaputureMoveFlag)
 		moves = append(moves, move)
 	}
 

diff --git a/internal/chess/position.go b/internal/chess/position.go
@@ -568,7 +568,7 @@ func (p *Position) MakeMove(move Move) error {
 		return fmt.Errorf("%w: tyring to move opponent's piece with %s", ErrInvalidMove, move)
 	}
 
-	capturePiece := move.capturePiece
+	capturePiece, _ := p.GetPieceAt(move.To())
 	if movingPiece.Color() == capturePiece.Color() {
 		return fmt.Errorf("%w: trying to capture piece of same color with %s", ErrInvalidMove, move)
 	}
@@ -619,7 +619,7 @@ func (p *Position) MakeMove(move Move) error {
 			}
 		}
 
-		if move.Captures() {
+		if move.IsCapture() {
 			p.clearPiece(to)
 
 			if capturePiece.Type() == Rook {
@@ -765,13 +765,14 @@ func (p *Position) MakeUciMove(uci string) error {
 		moveType = EnPassantMove
 	}
 
-	move := NewMove(from, to, moveType, NoMoveFlag)
-
-	capturePiece, err := p.GetPieceAt(to)
-	if err == nil {
-		move.WithCapture(capturePiece)
+	flag := QuietMoveFlag
+	capturePiece, _ := p.GetPieceAt(to)
+	if capturePiece != EmptyPiece {
+		flag = CaputureMoveFlag
 	}
 
+	move := NewMove(from, to, moveType, flag)
+
 	if len(uci) > 4 {
 		switch uci[4] {
 		case 'n':