def test___eq__(self):
self.assertEqual(True, Fen().__eq__(Fen()))
def test___getitem__(self):
fen = Fen()
self.assertEqual('R', fen.__getitem__(Square('a1')))
def test_text(self):
self.assertEqual(Fen.start, Fen().text)
def test_turn(self):
self.assertEqual('w', Fen().turn)
class Position(object):
"""Represents a chess position.
:param fen:
Optional. The FEN of the position. Defaults to the standard
chess start position.
Squares can be accessed via their name, a square object and their
x88 index:
>>> import chess
>>> pos = chess.Position()
>>> pos["e4"] = Piece("Q")
>>> pos[chess.Square("e4")]
Piece('Q')
>>> del pos["a8"]
>>> pos[0] # 0 is the x88 index of a8.
None
"""
def __init__(self, fen=Fen.start):
self.fen = Fen(fen)
self._pieces = self.fen._pieces
def copy(self):
"""Gets a copy of the position. The copy will not change when the
original instance is changed.
:return:
An exact copy of the positon.
"""
return copy.deepcopy(self)
def get_pseudo_legal_moves(self, source=None):
""":yield: Pseudo legal moves in the current position.
:param source: The source square to limit moves or None for
all possible moves.
"""
tomove = self.fen._to_move
for x88 in [
x88 for x88 in Square._x88_squares.keys()
if self._pieces[x88] and Piece.color(self._pieces[x88]) ==
tomove and (source is None or x88 == source._x88)
]:
piece = self._pieces[x88]
klass = Piece.klass(piece)
# pawn moves
if klass == PAWN:
single, double, capleft, capright = X88.PAWN_OFFSETS[tomove]
# Single square ahead. Do not capture.
offset = x88 + single
if not self._pieces[offset]:
# Promotion.
if X88.is_backrank(offset, tomove):
for promote_to in Piece.promote_to:
yield Move.from_x88(x88, offset, promote_to)
else:
yield Move.from_x88(x88, offset)
# Two squares ahead. Do not capture.
if X88.is_secondrank(x88, tomove):
offset = x88 + double
if not self._pieces[offset]:
yield Move.from_x88(x88, offset)
# Pawn captures.
for cap in [capleft, capright]:
offset = x88 + cap
if offset & X88.X88:
continue
target = self._pieces[offset]
if target and Piece.color(target) != tomove:
# Promotion.
if X88.is_backrank(offset, tomove):
for promote_to in Piece.promote_to:
yield Move.from_x88(x88, offset, promote_to)
else:
yield Move.from_x88(x88, offset)
# En-passant.
elif not target and offset == self.fen._ep:
yield Move.from_x88(target, self.fen._ep)
#piece moves
else:
# for each a direction a piece moves in
for offset in X88.PIECE_OFFSETS[Piece.klass(piece)]:
t_x88 = x88 + offset
# while we do not fall off the board
while not t_x88 & 0x88:
# if there was not piece to attack then yield a quiet move
if not self._pieces[t_x88]:
yield Move.from_x88(x88, t_x88)
# do not break out
# else there is a piece there
else:
# if we can attack generate a move
if Piece.color(self._pieces[t_x88]) != tomove:
yield Move.from_x88(x88, t_x88)
# we hit something so break out
break
# Knight and king do not go multiple times in their direction.
if klass in [KNIGHT, KING]:
break
# travel down the board in the direction
t_x88 += offset
# castling moves
opponent = Piece.opposite_color(tomove)
ok = True
# get possible castling for the side to move
for castle in [
c for c in self.fen._castle_rights if Piece.color(c) == tomove
]:
(square, enum), _ = Piece.castle_squares[castle]
king = Square(square)
if Piece.klass(castle) == KING:
direc = 1
else:
direc = -1
# for offset in the squares the king will travel
for offset in range(0, 3):
s = Square.from_x88(king._x88 + (offset * direc))
# if we are not the king square and we are occuppied
if offset and self._pieces[s._x88]:
ok = False
break
# if we are trying to travel through check
if self.is_attacked(opponent, s):
ok = False
break
# kludge: we have to check occupancy for one more square on the queen side
if direc == -1 and self._pieces[s._x88 - 1]:
ok = False
if ok:
yield Move(king, s)
def is_attacked(self, color, square):
"""Checks whether a square is attacked.
:param color:
Check if this player is attacking.
:param square:
The square the player might be attacking.
:return:
A boolean indicating whether the given square is attacked
by the player of the given color.
"""
try:
self.get_attackers(color, square).next()
return True
except StopIteration:
return False
def get_attackers(self, color, square):
"""Gets the attackers of a specific square.
:param color:
Filter attackers by this piece color.
:param square:
The square to check for.
:yield:
Source squares of the attack.
"""
if not color in [BLACK, WHITE]:
raise KeyError("Invalid color: %s." % repr(color))
for x88, source in Square._x88_squares.iteritems():
piece = self._pieces[x88]
if not piece or Piece.color(piece) != color:
continue
difference = x88 - square._x88
index = difference + X88.ATTACKER_DIFF
klass = Piece.klass(piece)
if X88.ATTACKS[index] & (1 << X88.SHIFTS[klass]):
# Handle pawns.
if klass == PAWN:
if difference > 0:
if Piece.color(piece) == WHITE:
yield source
else:
if Piece.color(piece) == BLACK:
yield source
continue
# Handle knights and king.
if klass in [KNIGHT, KING]:
yield source
# Handle the others.
offset = X88.RAYS[index]
j = source._x88 + offset
blocked = False
while j != square._x88:
if self._pieces[j]:
blocked = True
break
j += offset
if not blocked:
yield source
def make_move(self, move, validate=True):
"""Makes a move.
:param move:
The move to make.
:param validate:
Defaults to `True`. Whether the move should be validated.
:return:
Making a move changes the position object. The same
(changed) object is returned for chainability.
:raise MoveError:
If the validate parameter is `True` and the move is not
legal in the position.
"""
#if validate:
if validate:
if move not in self.get_legal_moves(source=move.source):
raise MoveError("%s is not a legal move in the position %s." %
(move, self.fen))
piece = self._pieces[move._source_x88]
capture = self._pieces[move._target_x88]
target = move.target
source = move.source
# Move the piece.
self._pieces[move._target_x88] = piece
self._pieces[move._source_x88] = None
# It is the next players turn.
ocolor = Piece.opposite_color(self.fen._to_move)
self.fen._to_move = ocolor
# Pawn moves.
self._ep = None
if Piece.klass(piece) == PAWN:
# En-passant.
if target.x != source.x and not capture:
offset = 16 if self.fen._to_move == WHITE else -16
self._pieces[target.x88() + offset] = None
capture = True
# If big pawn move, set the en-passant file.
if abs(target.y - source.y) == 2:
if self.get_theoretical_ep_right(target.x):
self._ep = move.target
# Promotion.
if move.promotion:
self._pieces[move.target._x88] = move.promotion
# Potential castling.
if Piece.klass(piece) == KING:
steps = move.target.x - move.source.x
if abs(steps) == 2:
# Queen-side castling.
if steps == -2:
rook_target = move.target.x88 + 1
rook_source = move.target.x88 - 2
# King-side castling.
else:
rook_target = move.target.x88 - 1
rook_source = move.target.x88 + 1
self._pieces[rook_target] = self._pieces[rook_source]
self._pieces[rook_source] = None
# Update castling rights.
for klass in self.fen._castle_rights:
if not self.get_theoretical_castling_right(klass):
self.fen._castle_rights.remove(klass)
# XXX Castling rights can only be removed
#self.set_castling_right(klass, False)
# Increment the 50 move half move counter.
if Piece.klass(piece) == PAWN or capture:
self.fen._fifty_move = 0
else:
self.fen._fifty_move += 1
# Increment the move number.
if self.fen._to_move == WHITE:
self.fen._full_move += 1
return self
def get_legal_moves(self, source=None):
""":yield: All legal moves in the current position."""
for move in self.get_pseudo_legal_moves(source=source):
potential_position = self.copy()
potential_position.make_move(move, False)
if not potential_position.is_king_attacked(self.fen._to_move):
yield move
def is_king_attacked(self, color):
""":return: Whether the king of the given color is attacked.
:param color: `"w"` or `"b"`.
"""
square = self.get_king(color)
if square:
return self.is_attacked(Piece.opposite_color(color), square)
# XXX No king?
else:
return False
def get_king(self, color):
"""Gets the square of the king.
:param color:
`"w"` for the white players king. `"b"` for the black
players king.
:return:
The first square with a matching king or `None` if that
player has no king.
"""
#if not color in ["w", "b"]:
# raise KeyError("Invalid color: %s." % repr(color))
for square, piece in [(s, self._pieces[s._x88])
for s in Square.get_all()
if self._pieces[s._x88]]:
if Piece.is_klass_and_color(piece, KING, color):
return square
def get_theoretical_ep_right(self, x):
"""Checks if a player could have an ep-move in theory from
looking just at the piece positions.
:param file:
The file to check as a letter between `"a"` and `"h"`.
:return:
A boolean indicating whether the player could theoretically
have that en-passant move.
"""
if x < 0 or x > 7:
raise ValueError(x)
'''
3 states of en-passant
p. pP ..
.. .. .p
.P .. ..
'''
# Check there is a pawn on the right rank for e.p.
y = 3 if self.fen._to_move == WHITE else 4
x88 = X88.from_x_and_y(x, y)
piece = self._pieces[x88]
if not piece:
return False
# If the square is not an opposite colored pawn then its not possible.
ocolor = Piece.opposite_color(self.fen._to_move)
if not Piece.is_klass_and_color(piece, PAWN, ocolor):
return False
# If the square below the pawn is not empty then it not possible.
y = 2 if self.fen.turn == WHITE else 5
x88 = X88.from_x_and_y(x, y)
if self[x88]:
return False
# If there is not pawn of opposite color on a neighboring file then its not possible.
xs = [_x for _x in range(8) if _x >= 0 and _x < 8 and abs(x - _x) == 1]
for _x in xs:
x88 = X88.from_x_and_y(_x, y)
piece = self._pieces[x88]
if Piece.is_klass_and_color(
piece, PAWN, Piece.opposite_color(self.fen._to_move)):
return True
# Else its just not possible.
return False
def get_theoretical_castling_right(self, klass):
"""Checks if a player could have a castling right in theory from
looking just at the piece positions.
:param klass:
The type of castling move to check. See
`Position.get_castling_right(type)` for values.
:return:
A boolean indicating whether the player could theoretically
have that castling right.
"""
if klass not in Piece.castleclass:
raise KeyError(klass)
# TODO: Support Chess960.
for square, enum in Piece.castle_squares[klass]:
piece = self._pieces[Square(square)._x88]
if not piece or Piece.enum(piece) != enum:
return False
return True
def is_check(self):
""":return: Whether the current player is in check."""
return self.is_king_attacked(self.fen._to_move)
def is_checkmate(self):
""":return: Whether the current player has been checkmated."""
if not self.is_check():
return False
else:
try:
self.get_legal_moves().next()
return False
except StopIteration:
return True
def is_stalemate(self):
""":return: Whether the current player is in stalemate."""
if self.is_check():
return False
else:
try:
self.get_legal_moves().next()
return False
except StopIteration:
return True
def get_piece_counts(self, colors=[WHITE, BLACK]):
"""Counts the pieces on the board.
:param color:
list of colors to check. Defualts to black and white
:return:
A dictionary of piece counts, keyed by lowercase piece type
letters.
"""
#if not color in ["w", "b", "wb", "bw"]:
# raise KeyError(
# "Expected color filter to be one of 'w', 'b', 'wb', 'bw', "
# "got: %s." % repr(color))
counts = {
PAWN: 0,
BISHOP: 0,
KNIGHT: 0,
ROOK: 0,
KING: 0,
QUEEN: 0,
}
for piece in self._pieces:
if piece and Piece.color(piece) in colors:
counts[Piece.klass(piece)] += 1
return counts
def is_insufficient_material(self):
"""Checks if there is sufficient material to mate.
Mating is impossible in:
* A king versus king endgame.
* A king with bishop versus king endgame.
* A king with knight versus king endgame.
* A king with bishop versus king with bishop endgame, where both
bishops are on the same color. Same goes for additional
bishops on the same color.
Assumes that the position is valid and each player has exactly
one king.
:return:
Whether there is insufficient material to mate.
"""
piece_counts = self.get_piece_counts()
# King versus king.
if sum(piece_counts.values()) == 2:
return True
# King and knight or bishop versus king.
elif sum(piece_counts.values()) == 3:
if piece_counts["b"] == 1 or piece_counts["n"] == 1:
return True
# Each player with only king and any number of bishops,
# where all bishops are on the same color.
elif sum(piece_counts.values()) == 2 + piece_counts[BISHOP]:
white_has_bishop = self.get_piece_counts([WHITE])[BISHOP] != 0
black_has_bishop = self.get_piece_counts([BLACK])[BISHOP] != 0
if white_has_bishop and black_has_bishop:
color = None
for square in Square.get_all():
p = self._pieces[square._x88]
if p and Piece.klass(p) == BISHOP:
if color and color != square.is_light():
return False
color = square.is_light()
return True
return False
def is_game_over(self):
"""Checks if the game is over.
:return:
Whether the game is over by the rules of chess,
disregarding that players can agree on a draw, claim a draw
or resign.
"""
return (self.is_checkmate() or self.is_stalemate()
or self.is_insufficient_material())
def __str__(self):
return str(self.fen)
def __repr__(self):
return "Position(%s)" % repr(str(self.fen))
def __eq__(self, other):
return self.fen == other.fen
def __ne__(self, other):
return self.fen != other.fen
def __hash__(self):
hasher = ZobristHasher(ZobristHasher.POLYGLOT_RANDOM_ARRAY)
return hasher.hash_position(self)
def __getitem__(self, square):
return self.fen.__getitem__(square)
def __setitem__(self, square, piece):
self.fen.__setitem__(square, piece)
def __delitem__(self, square):
self.fen.__delitem__(square)
#TODO
def clear_board(self):
pass
def reset(self):
pass
# do we want this public?
def toggle_turn(self):
"""Toggles whos turn it is."""
def test___hash__(self):
hash(Fen())
def test_castle_rights(self):
self.assertEqual('KQkq', Fen().castle_rights)
def test___repr__(self):
self.assertEqual("Position('%s')" % Fen(), repr(self.pos))
def test___setitem__(self):
f, s = Fen(), Square('a1')
f[s] = 'K'
self.assertEqual('K', f[s])
def test___str__(self):
self.assertEqual(Fen.start, Fen().__str__())
def test___repr__(self):
# fen = Fen(fen)
self.assertEqual('Fen(\'' + Fen.start + '\')', Fen().__repr__())
def test___ne__(self):
self.assertEqual(False, Fen().__ne__(Fen()))
def test___init__(self):
Fen()
Fen('rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w - - 0 1')
Fen('rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w - e3 0 1')
with self.assertRaises(FenError):
Fen('rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0')
with self.assertRaises(FenError):
Fen('rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP w KQkq - 0')
with self.assertRaises(FenError):
Fen('rnbqkbnr/pppppppp/71/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1')
with self.assertRaises(FenError):
Fen('Znbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1')
with self.assertRaises(FenError):
Fen('rnbqkbnr/ppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1')
with self.assertRaises(FenError):
Fen('rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR Z KQkq - 0 1')
with self.assertRaises(FenError):
Fen('rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w ZQkq - 0 1')
with self.assertRaises(FenError):
Fen('rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w - e4 0 1')
with self.assertRaises(FenError):
Fen('rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - -1 1')
with self.assertRaises(FenError):
Fen('rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - Z 1')
with self.assertRaises(FenError):
Fen('rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 0')
with self.assertRaises(FenError):
Fen('rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 Z')
class Position(object):
"""Represents a chess position.
:param fen:
Optional. The FEN of the position. Defaults to the standard
chess start position.
Squares can be accessed via their name, a square object and their
x88 index:
>>> import chess
>>> pos = chess.Position()
>>> pos["e4"] = Piece("Q")
>>> pos[chess.Square("e4")]
Piece('Q')
>>> del pos["a8"]
>>> pos[0] # 0 is the x88 index of a8.
None
"""
def __init__(self, fen=Fen.start):
self.fen = Fen(fen)
self._pieces = self.fen._pieces
def copy(self):
"""Gets a copy of the position. The copy will not change when the
original instance is changed.
:return:
An exact copy of the positon.
"""
return copy.deepcopy(self)
def get_pseudo_legal_moves(self, source=None):
""":yield: Pseudo legal moves in the current position.
:param source: The source square to limit moves or None for
all possible moves.
"""
tomove = self.fen._to_move
for x88 in [ x88 for x88 in Square._x88_squares.keys()
if self._pieces[x88]
and Piece.color(self._pieces[x88]) == tomove
and (source is None or x88 == source._x88)]:
piece = self._pieces[x88]
klass = Piece.klass(piece)
# pawn moves
if klass == PAWN:
single, double, capleft, capright = X88.PAWN_OFFSETS[tomove]
# Single square ahead. Do not capture.
offset = x88 + single
if not self._pieces[offset]:
# Promotion.
if X88.is_backrank(offset, tomove):
for promote_to in Piece.promote_to:
yield Move.from_x88(x88, offset, promote_to)
else:
yield Move.from_x88(x88, offset)
# Two squares ahead. Do not capture.
if X88.is_secondrank(x88, tomove):
offset = x88 + double
if not self._pieces[offset]:
yield Move.from_x88(x88, offset)
# Pawn captures.
for cap in [capleft, capright]:
offset = x88 + cap
if offset & X88.X88:
continue
target = self._pieces[offset]
if target and Piece.color(target) != tomove:
# Promotion.
if X88.is_backrank(offset, tomove):
for promote_to in Piece.promote_to:
yield Move.from_x88(x88, offset, promote_to)
else:
yield Move.from_x88(x88, offset)
# En-passant.
elif not target and offset == self.fen._ep:
yield Move.from_x88(target, self.fen._ep)
#piece moves
else:
# for each a direction a piece moves in
for offset in X88.PIECE_OFFSETS[Piece.klass(piece)]:
t_x88 = x88 + offset
# while we do not fall off the board
while not t_x88 & 0x88:
# if there was not piece to attack then yield a quiet move
if not self._pieces[t_x88]:
yield Move.from_x88(x88, t_x88)
# do not break out
# else there is a piece there
else:
# if we can attack generate a move
if Piece.color(self._pieces[t_x88]) != tomove:
yield Move.from_x88(x88, t_x88)
# we hit something so break out
break
# Knight and king do not go multiple times in their direction.
if klass in [KNIGHT, KING]:
break
# travel down the board in the direction
t_x88 += offset
# castling moves
opponent = Piece.opposite_color(tomove)
ok = True
# get possible castling for the side to move
for castle in [c for c in self.fen._castle_rights if Piece.color(c) == tomove]:
(square, enum), _ = Piece.castle_squares[castle]
king = Square(square)
if Piece.klass(castle) == KING:
direc = 1
else:
direc = -1
# for offset in the squares the king will travel
for offset in range(0, 3):
s = Square.from_x88(king._x88 + (offset * direc))
# if we are not the king square and we are occuppied
if offset and self._pieces[s._x88]:
ok = False
break
# if we are trying to travel through check
if self.is_attacked(opponent, s):
ok = False
break
# kludge: we have to check occupancy for one more square on the queen side
if direc == -1 and self._pieces[s._x88 - 1]:
ok = False
if ok:
yield Move(king, s)
def is_attacked(self, color, square):
"""Checks whether a square is attacked.
:param color:
Check if this player is attacking.
:param square:
The square the player might be attacking.
:return:
A boolean indicating whether the given square is attacked
by the player of the given color.
"""
try:
self.get_attackers(color, square).next()
return True
except StopIteration:
return False
def get_attackers(self, color, square):
"""Gets the attackers of a specific square.
:param color:
Filter attackers by this piece color.
:param square:
The square to check for.
:yield:
Source squares of the attack.
"""
if not color in [BLACK, WHITE]:
raise KeyError("Invalid color: %s." % repr(color))
for x88, source in Square._x88_squares.iteritems():
piece = self._pieces[x88]
if not piece or Piece.color(piece) != color:
continue
difference = x88 - square._x88
index = difference + X88.ATTACKER_DIFF
klass = Piece.klass(piece)
if X88.ATTACKS[index] & (1 << X88.SHIFTS[klass]):
# Handle pawns.
if klass == PAWN:
if difference > 0:
if Piece.color(piece) == WHITE:
yield source
else:
if Piece.color(piece) == BLACK:
yield source
continue
# Handle knights and king.
if klass in [KNIGHT, KING]:
yield source
# Handle the others.
offset = X88.RAYS[index]
j = source._x88 + offset
blocked = False
while j != square._x88:
if self._pieces[j]:
blocked = True
break
j += offset
if not blocked:
yield source
def make_move(self, move, validate=True):
"""Makes a move.
:param move:
The move to make.
:param validate:
Defaults to `True`. Whether the move should be validated.
:return:
Making a move changes the position object. The same
(changed) object is returned for chainability.
:raise MoveError:
If the validate parameter is `True` and the move is not
legal in the position.
"""
#if validate:
if validate:
if move not in self.get_legal_moves(source=move.source):
raise MoveError(
"%s is not a legal move in the position %s." % (move, self.fen))
piece = self._pieces[move._source_x88]
capture = self._pieces[move._target_x88]
target = move.target
source = move.source
# Move the piece.
self._pieces[move._target_x88] = piece
self._pieces[move._source_x88] = None
# It is the next players turn.
ocolor = Piece.opposite_color(self.fen._to_move)
self.fen._to_move = ocolor
# Pawn moves.
self._ep = None
if Piece.klass(piece) == PAWN:
# En-passant.
if target.x != source.x and not capture:
offset = 16 if self.fen._to_move == WHITE else -16
self._pieces[target.x88() + offset] = None
capture = True
# If big pawn move, set the en-passant file.
if abs(target.y - source.y) == 2:
if self.get_theoretical_ep_right(target.x):
self._ep = move.target
# Promotion.
if move.promotion:
self._pieces[move.target._x88] = move.promotion
# Potential castling.
if Piece.klass(piece) == KING:
steps = move.target.x - move.source.x
if abs(steps) == 2:
# Queen-side castling.
if steps == -2:
rook_target = move.target.x88 + 1
rook_source = move.target.x88 - 2
# King-side castling.
else:
rook_target = move.target.x88 - 1
rook_source = move.target.x88 + 1
self._pieces[rook_target] = self._pieces[rook_source]
self._pieces[rook_source] = None
# Update castling rights.
for klass in self.fen._castle_rights:
if not self.get_theoretical_castling_right(klass):
self.fen._castle_rights.remove(klass)
# XXX Castling rights can only be removed
#self.set_castling_right(klass, False)
# Increment the 50 move half move counter.
if Piece.klass(piece) == PAWN or capture:
self.fen._fifty_move = 0
else:
self.fen._fifty_move += 1
# Increment the move number.
if self.fen._to_move == WHITE:
self.fen._full_move += 1
return self
def get_legal_moves(self, source=None):
""":yield: All legal moves in the current position."""
for move in self.get_pseudo_legal_moves(source=source):
potential_position = self.copy()
potential_position.make_move(move, False)
if not potential_position.is_king_attacked(self.fen._to_move):
yield move
def is_king_attacked(self, color):
""":return: Whether the king of the given color is attacked.
:param color: `"w"` or `"b"`.
"""
square = self.get_king(color)
if square:
return self.is_attacked(Piece.opposite_color(color), square)
# XXX No king?
else:
return False
def get_king(self, color):
"""Gets the square of the king.
:param color:
`"w"` for the white players king. `"b"` for the black
players king.
:return:
The first square with a matching king or `None` if that
player has no king.
"""
#if not color in ["w", "b"]:
# raise KeyError("Invalid color: %s." % repr(color))
for square, piece in [(s, self._pieces[s._x88]) for s in Square.get_all() if self._pieces[s._x88]]:
if Piece.is_klass_and_color(piece, KING, color):
return square
def get_theoretical_ep_right(self, x):
"""Checks if a player could have an ep-move in theory from
looking just at the piece positions.
:param file:
The file to check as a letter between `"a"` and `"h"`.
:return:
A boolean indicating whether the player could theoretically
have that en-passant move.
"""
if x < 0 or x > 7:
raise ValueError(x)
'''
3 states of en-passant
p. pP ..
.. .. .p
.P .. ..
'''
# Check there is a pawn on the right rank for e.p.
y = 3 if self.fen._to_move == WHITE else 4
x88 = X88.from_x_and_y(x, y)
piece = self._pieces[x88]
if not piece:
return False
# If the square is not an opposite colored pawn then its not possible.
ocolor = Piece.opposite_color(self.fen._to_move)
if not Piece.is_klass_and_color(piece, PAWN, ocolor):
return False
# If the square below the pawn is not empty then it not possible.
y = 2 if self.fen.turn == WHITE else 5
x88 = X88.from_x_and_y(x, y)
if self[x88]:
return False
# If there is not pawn of opposite color on a neighboring file then its not possible.
xs = [_x for _x in range(8) if _x>=0 and _x<8 and abs(x-_x) == 1]
for _x in xs:
x88 = X88.from_x_and_y(_x, y)
piece = self._pieces[x88]
if Piece.is_klass_and_color(piece, PAWN, Piece.opposite_color(self.fen._to_move)):
return True
# Else its just not possible.
return False
def get_theoretical_castling_right(self, klass):
"""Checks if a player could have a castling right in theory from
looking just at the piece positions.
:param klass:
The type of castling move to check. See
`Position.get_castling_right(type)` for values.
:return:
A boolean indicating whether the player could theoretically
have that castling right.
"""
if klass not in Piece.castleclass:
raise KeyError(klass)
# TODO: Support Chess960.
for square, enum in Piece.castle_squares[klass]:
piece = self._pieces[Square(square)._x88]
if not piece or Piece.enum(piece) != enum:
return False
return True
def is_check(self):
""":return: Whether the current player is in check."""
return self.is_king_attacked(self.fen._to_move)
def is_checkmate(self):
""":return: Whether the current player has been checkmated."""
if not self.is_check():
return False
else:
try:
self.get_legal_moves().next()
return False
except StopIteration:
return True
def is_stalemate(self):
""":return: Whether the current player is in stalemate."""
if self.is_check():
return False
else:
try:
self.get_legal_moves().next()
return False
except StopIteration:
return True
def get_piece_counts(self, colors=[WHITE, BLACK]):
"""Counts the pieces on the board.
:param color:
list of colors to check. Defualts to black and white
:return:
A dictionary of piece counts, keyed by lowercase piece type
letters.
"""
#if not color in ["w", "b", "wb", "bw"]:
# raise KeyError(
# "Expected color filter to be one of 'w', 'b', 'wb', 'bw', "
# "got: %s." % repr(color))
counts = {
PAWN: 0,
BISHOP: 0,
KNIGHT: 0,
ROOK: 0,
KING: 0,
QUEEN: 0,
}
for piece in self._pieces:
if piece and Piece.color(piece) in colors:
counts[Piece.klass(piece)] += 1
return counts
def is_insufficient_material(self):
"""Checks if there is sufficient material to mate.
Mating is impossible in:
* A king versus king endgame.
* A king with bishop versus king endgame.
* A king with knight versus king endgame.
* A king with bishop versus king with bishop endgame, where both
bishops are on the same color. Same goes for additional
bishops on the same color.
Assumes that the position is valid and each player has exactly
one king.
:return:
Whether there is insufficient material to mate.
"""
piece_counts = self.get_piece_counts()
# King versus king.
if sum(piece_counts.values()) == 2:
return True
# King and knight or bishop versus king.
elif sum(piece_counts.values()) == 3:
if piece_counts["b"] == 1 or piece_counts["n"] == 1:
return True
# Each player with only king and any number of bishops,
# where all bishops are on the same color.
elif sum(piece_counts.values()) == 2 + piece_counts[BISHOP]:
white_has_bishop = self.get_piece_counts([WHITE])[BISHOP] != 0
black_has_bishop = self.get_piece_counts([BLACK])[BISHOP] != 0
if white_has_bishop and black_has_bishop:
color = None
for square in Square.get_all():
p = self._pieces[square._x88]
if p and Piece.klass(p) == BISHOP:
if color and color != square.is_light():
return False
color = square.is_light()
return True
return False
def is_game_over(self):
"""Checks if the game is over.
:return:
Whether the game is over by the rules of chess,
disregarding that players can agree on a draw, claim a draw
or resign.
"""
return (self.is_checkmate() or self.is_stalemate() or
self.is_insufficient_material())
def __str__(self):
return str(self.fen)
def __repr__(self):
return "Position(%s)" % repr(str(self.fen))
def __eq__(self, other):
return self.fen == other.fen
def __ne__(self, other):
return self.fen != other.fen
def __hash__(self):
hasher = ZobristHasher(ZobristHasher.POLYGLOT_RANDOM_ARRAY)
return hasher.hash_position(self)
def __getitem__(self, square):
return self.fen.__getitem__(square)
def __setitem__(self, square, piece):
self.fen.__setitem__(square, piece)
def __delitem__(self, square):
self.fen.__delitem__(square)
#TODO
def clear_board(self): pass
def reset(self): pass
# do we want this public?
def toggle_turn(self): """Toggles whos turn it is."""
def test_ep_square(self):
self.assertEqual('-', Fen().ep_square)
def __init__(self, fen=Fen.start):
self.fen = Fen(fen)
self._pieces = self.fen._pieces
def test_fifty_move(self):
self.assertEqual(0, Fen().fifty_move)
def test___str__(self):
self.assertEqual(str(Fen()), str(self.pos))
self.assertEqual(False, str(self.pos) == str(self.pos_other))
def test_fullmove(self):
self.assertEqual(1, Fen().full_move)
def __init__(self, fen=Fen.start):
self.fen = Fen(fen)
self._pieces = self.fen._pieces
def test___getitem__(self):
fen = Fen()
self.assertEqual('R', fen.__getitem__(Square('a1')))