def is_defended(board: Board, piece: Piece, square: Square) -> bool:
if board.attackers(piece.color, square):
return True
# ray defense https://lichess.org/editor/6k1/3q1pbp/2b1p1p1/1BPp4/rp1PnP2/4PRNP/4Q1P1/4B1K1_w_-_-_0_1
for attacker in board.attackers(not piece.color, square):
if board.piece_at(attacker).piece_type in ray_piece_types:
bc = board.copy(stack = False)
bc.remove_piece_at(attacker)
if bc.attackers(piece.color, square):
return True
return False
def is_in_bad_spot(board: Board, square: Square) -> bool:
# hanging or takeable by lower piece
piece = board.piece_at(square)
assert (piece)
return (bool(board.attackers(not piece.color, square))
and (is_hanging(board, piece, square)
or can_be_taken_by_lower_piece(board, piece, square)))
def can_be_taken_by_lower_piece(board: Board, piece: Piece,
square: Square) -> bool:
for attacker_square in board.attackers(not piece.color, square):
attacker = board.piece_at(attacker_square)
assert attacker
if attacker.piece_type != chess.KING and values[
attacker.piece_type] < values[piece.piece_type]:
return True
return False
def evaluate(board: chess.Board):
ENEMY = {chess.WHITE: chess.BLACK, chess.BLACK: chess.WHITE}
score = 0
if board.result() == "1-0" or board.result() == "0-1":
score += 9999
if board.is_check():
score += 10
for sq in chess.SQUARES:
score += len(board.attackers(board.turn,
sq)) * VALUE[board.piece_type_at(sq)]
score -= len(board.attackers(ENEMY[board.turn],
sq)) * VALUE[board.piece_type_at(sq)]
return score
def get_attacking_pieces(board: chess.Board, attacking_color: chess.Color, square: chess.Square) -> [chess.PieceType]:
piece_types = []
attacking_squares = board.attackers(attacking_color, square)
for attacking_square in attacking_squares:
if board.is_pinned(attacking_color, attacking_square) == False:
piece_type = board.piece_type_at(attacking_square)
piece_types.append(piece_type)
return piece_types
def attacker_pieces(board: Board, color: Color, square: Square) -> List[Piece]:
return [
p for p in [board.piece_at(s) for s in board.attackers(color, square)]
if p
]
