def legal_drop_squares_mask(self) -> chess.Bitboard:
king = self.king(self.turn)
if king is None:
return ~self.occupied
king_attackers = self.attackers_mask(not self.turn, king)
if not king_attackers:
return ~self.occupied
elif chess.popcount(king_attackers) == 1:
return chess.between(king, chess.msb(king_attackers)) & ~self.occupied
else:
return chess.BB_EMPTY
def slide_move(board: chess.Board, move: chess.Move) -> Optional[chess.Move]:
# We iterate longest to shortest so the revised move is the longest pseudo-legal move.
# If the to-square < from-square then we want our list in sorted order.
# Otherwise we want it in reverse order.
# In either case, we need to add the to-square to the front of our list manually.
squares = chess.SquareSet(chess.between(move.from_square, move.to_square))
if move.to_square > move.from_square:
squares = reversed(squares)
for slide_square in [move.to_square] + list(squares):
revised = chess.Move(move.from_square, slide_square, move.promotion)
if board.is_pseudo_legal(revised):
return revised
return None
def slide_move(board: chess.Board, move: chess.Move) -> Optional[chess.Move]:
psuedo_legal_moves = list(board.generate_pseudo_legal_moves())
squares = list(
chess.SquareSet(chess.between(move.from_square,
move.to_square))) + [move.to_square]
squares = sorted(squares,
key=lambda s: chess.square_distance(s, move.from_square),
reverse=True)
for slide_square in squares:
revised = chess.Move(move.from_square, slide_square, move.promotion)
if revised in psuedo_legal_moves:
return revised
return None
def is_illegal_castle(board: chess.Board, move: chess.Move) -> bool:
if not board.is_castling(move):
return False
# illegal without kingside rights
if board.is_kingside_castling(move) and not board.has_kingside_castling_rights(board.turn):
return True
# illegal without queenside rights
if board.is_queenside_castling(move) and not board.has_queenside_castling_rights(board.turn):
return True
# illegal if any pieces are between king & rook
rook_square = chess.square(7 if board.is_kingside_castling(move) else 0, chess.square_rank(move.from_square))
between_squares = chess.SquareSet(chess.between(move.from_square, rook_square))
if any(map(lambda s: board.piece_at(s), between_squares)):
return True
# its legal
return False
