def place_piece(self, piece, square):
""" Places piece on board at square specified
Input piece can be str(K) or Piece
Input square can be one of:
- str('E4'),
- tuple of array coordinates((0,2))
- Piece with file and rank properties """
if type(square) is str:
file = FILE[square[0]]
rank = RANK[square[1]]
elif type(square) is Piece:
file = square.file
rank = square.rank
else:
rank = square[0]
file = square[1]
if type(piece) is str:
piece = Piece(piece, rank=rank, file=file)
else:
piece.rank = rank
piece.file = file
self.BOARD[rank][file] = piece
def get_possible_squares(self, piece=None, square=None):
""" Returns a list of possible squares availale to move to.
Input needed: One of: piece or square, or both
piece can be one of: string - 'K'
Piece - Piece('K')
square can be one of: string - 'E4'
array coordinates - [3,5]
Usage: get_possible_squares(piece='K', square='E4')
get_possible_squares(square='E4')
get_possible_squares(piece=<Piece>) // Piece with .file and .rank
get_possible_squares(square=<Piece>) // Piece with .file and .rank
"""
#print(f"piece:{piece}, square:{square}")
# if both piece and square are None
if not piece and not square:
return None
# piece can be string or Piece object or empty
if type(piece) is str:
piece_obj = Piece(piece)
elif type(piece) is Piece:
piece_obj = piece
else:
piece_obj = self.board.BOARD[RANK[square[1]]][FILE[square[0]]]
# square can be empty, string or array coordinates
if not square:
file = piece_obj.file
rank = piece_obj.rank
elif type(square) is str:
file = FILE[square[0]]
rank = RANK[square[1]]
else:
file = square[1]
rank = square[0]
# If no piece enterred and square is EMPTY:
if not piece and self.board.BOARD[rank][file] is EMPTY:
return None
# If piece is newly created without file and rank
if not piece_obj.file:
piece_obj.file = file
piece_obj.rank = rank
# If not active colour
if piece_obj.colour is not self.whose_move():
return None
#print(f"get_possible_squares({piece_obj._id} on {Board.square_name((piece_obj.rank, piece_obj.file))})")
# Loop through directions of piece movements
possible_squares = []
for movement in piece_obj.movements:
distance = 0
possible_file = file
possible_rank = rank
max_distance = piece_obj.max_distance
# Loop until range of piece is exceeded
while distance != max_distance:
# If pawn on starting position
if piece_obj.name is PAWN:
if piece_obj.colour == WHITE and rank == 1 or \
piece_obj.colour == BLACK and rank == 6:
max_distance = 2
# copy board for testing in_check conditions
possible_board = Board(self.board.BOARD)
possible_file += movement[1]
possible_rank += movement[0]
# If passed edge of board
if possible_file < 0 or possible_file > 7 or \
possible_rank < 0 or possible_rank > 7:
#print("Can't move: off edge of board")
break
possible_square = possible_board.BOARD[possible_rank][
possible_file]
# If square is occupied
if possible_square is not EMPTY:
# If own piece in the way
if possible_square.colour == piece_obj.colour:
break
# If opposition piece in the way
else:
# If moving piece is a pawn
if piece_obj.name == PAWN:
# If forward pawn move
if movement in piece_obj.normal_movements:
break
# Test for putting self in check
possible_board.remove_piece((rank, file))
possible_board.place_piece(square=possible_square,
piece=piece_obj._id)
if self.in_check(board=possible_board,
colour=piece_obj.colour):
break
# Can capture piece
else:
possible_squares.append(
[possible_rank, possible_file])
break
# Square not occupied
else:
# If pawn
if piece_obj.name == PAWN:
# Can't move diagonal if not capturing unless en-passant
if movement in piece_obj.capture_movements:
if not self.en_passant_sq:
break
elif self.en_passant_sq and \
Board.square_name((possible_rank, possible_file)) != self.en_passant_sq.upper():
break
# If not on 2nd rank(WHITE) or 7th rank(BLACK): Can't move two squares
if piece_obj.colour == WHITE and rank != 1 and distance == 1 or \
piece_obj.colour == BLACK and rank != 6 and distance == 1:
break
# If Castling King
if piece_obj.name is KING and piece_obj.colour is WHITE:
if movement is E and self.castling_rights[0]:
if max_distance == 1:
max_distance = 2
if movement is W and self.castling_rights[1]:
if max_distance == 1:
max_distance = 2
elif piece_obj.name is KING and piece_obj.colour is BLACK:
if movement is E and self.castling_rights[2]:
if max_distance == 1:
max_distance = 2
if movement is W and self.castling_rights[3]:
if max_distance == 1:
max_distance = 2
# Test for putting self in check
possible_board.remove_piece((rank, file))
possible_board.place_piece(square=(possible_rank,
possible_file),
piece=piece_obj._id)
if not self.in_check(board=possible_board,
colour=piece_obj.colour):
possible_squares.append([possible_rank, possible_file])
else:
# Can't castle through a check
if piece_obj.name is KING:
max_distance = 1
distance += 1
if not possible_squares:
return None
else:
return possible_squares
