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_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 __init__(self, label):
if len(label) != 2:
raise ValueError(square)
try:
x = self.files.index(label[0])
y = self.ranks.index(label[1])
except ValueError:
raise ValueError(label)
self._x88 = X88.from_x_and_y(x, y)
def __init__(self, label):
if len(label) != 2:
raise ValueError(square)
try:
x = self.files.index(label[0])
y = self.ranks.index(label[1])
except ValueError:
raise ValueError(label)
self._x88 = X88.from_x_and_y(x, y)
def test_to_index(self):
self.assertEqual(X88.to_index(0), 0)
def test_is_backrank(self):
self.assertEqual(X88.is_backrank(0, piece.BLACK), True)
def file(self):
"""The file as a character in %s""" % self.files
return self.files[X88.to_x(self._x88)]
def y(self):
"""The y-coordinate, starting with 0 for the first rank."""
return X88.to_y(self._x88)
def y(self):
"""The y-coordinate, starting with 0 for the first rank."""
return X88.to_y(self._x88)
def x(self):
"""The x-coordinate, starting with 0 for the a-file."""
return X88.to_x(self._x88)
def test_from_index(self):
self.assertEqual(X88.from_index(0), 0)
def test_to_y(self):
self.assertEqual(X88.to_y(0), 0)
def test_to_index(self):
self.assertEqual(X88.to_index(0), 0)
def test_is_secondrank(self):
self.assertEqual(X88.is_secondrank(8, piece.WHITE), True)
def test_to_y(self):
self.assertEqual(X88.to_y(0), 0)
def rank(self):
"""The rank as a character in %s""" % self.ranks
return self.ranks[X88.to_y(self._x88)]
def test_from_index(self):
self.assertEqual(X88.from_index(0), 0)
def file(self):
"""The file as a character in %s""" % self.files
return self.files[X88.to_x(self._x88)]
def x(self):
"""The x-coordinate, starting with 0 for the a-file."""
return X88.to_x(self._x88)
def index(self):
"""An integer between 0 and %s where 0 represents Square('a1').""" % (
len(self.ranks) * len(self.files) - 1)
return X88.to_index(self._x88)
def rank(self):
"""The rank as a character in %s""" % self.ranks
return self.ranks[X88.to_y(self._x88)]
def test_from_x_and_y(self):
self.assertEqual(X88.from_x_and_y(0, 0), 0)
def index(self):
"""An integer between 0 and %s where 0 represents Square('a1').""" % (
len(self.ranks) * len(self.files) - 1)
return X88.to_index(self._x88)
def test_is_backrank(self):
self.assertEqual(X88.is_backrank(0, piece.BLACK), True)
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 test_is_secondrank(self):
self.assertEqual(X88.is_secondrank(8, piece.WHITE), True)
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 test_from_x_and_y(self):
self.assertEqual(X88.from_x_and_y(0,0), 0)
