Merge f1480fc into 45c823d

niklasf · Aug 31, 2020 · c023825 · c023825
2 parents 45c823d + f1480fc
commit c023825
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Showing 2 changed files with 30 additions and 7 deletions.
diff --git a/chess/__init__.py b/chess/__init__.py
@@ -1227,21 +1227,28 @@ def transform(self: BaseBoardT, f: Callable[[Bitboard], Bitboard]) -> BaseBoardT
         :func:`chess.shift_right()`.
 
         Alternatively, :func:`~chess.BaseBoard.apply_transform()` can be used
-        to apply the transformation in place.
+        to apply the transformation on the board.
         """
         board = self.copy()
         board.apply_transform(f)
         return board
 
+    def apply_mirror(self: BaseBoardT) -> None:
+        self.apply_transform(flip_vertical)
+        self.occupied_co[WHITE], self.occupied_co[BLACK] = self.occupied_co[BLACK], self.occupied_co[WHITE]
+
     def mirror(self: BaseBoardT) -> BaseBoardT:
         """
         Returns a mirrored copy of the board.
 
         The board is mirrored vertically and piece colors are swapped, so that
         the position is equivalent modulo color.
+
+        Alternatively, :func:`~chess.BaseBoard.apply_mirror()` can be used
+        to mirror the board.
         """
-        board = self.transform(flip_vertical)
-        board.occupied_co[WHITE], board.occupied_co[BLACK] = board.occupied_co[BLACK], board.occupied_co[WHITE]
+        board = self.copy()
+        board.apply_mirror()
         return board
 
     def copy(self: BaseBoardT) -> BaseBoardT:
@@ -3437,17 +3444,31 @@ def __eq__(self, board: object) -> bool:
     def apply_transform(self, f: Callable[[Bitboard], Bitboard]) -> None:
         super().apply_transform(f)
         self.clear_stack()
+        self.ep_square = None if self.ep_square is None else msb(f(BB_SQUARES[self.ep_square]))
+        self.castling_rights = f(self.castling_rights)
 
     def transform(self: BoardT, f: Callable[[Bitboard], Bitboard]) -> BoardT:
         board = self.copy(stack=False)
         board.apply_transform(f)
-        board.ep_square = None if self.ep_square is None else msb(f(BB_SQUARES[self.ep_square]))
-        board.castling_rights = f(self.castling_rights)
         return board
 
+    def apply_mirror(self: BoardT) -> None:
+        super().apply_mirror()
+        self.turn = not self.turn
+
     def mirror(self: BoardT) -> BoardT:
-        board = super().mirror()
-        board.turn = not self.turn
+        """
+        Returns a mirrored copy of the board.
+
+        The board is mirrored vertically and piece colors are swapped, so that
+        the position is equivalent modulo color. Also swap the "en passant" 
+        square, castling rights and turn.
+
+        Alternatively, :func:`~chess.Board.apply_mirror()` can be used
+        to mirror the board.
+        """
+        board = self.copy()
+        board.apply_mirror()
         return board
 
     def copy(self: BoardT, *, stack: Union[bool, int] = True) -> BoardT:

diff --git a/test.py b/test.py
@@ -1577,6 +1577,8 @@ def test_mirror(self):
         board = chess.Board("r1bq1r2/pp2n3/4N2k/3pPppP/1b1n2Q1/2N5/PP3PP1/R1B1K2R w KQ g6 0 15")
         mirrored = chess.Board("r1b1k2r/pp3pp1/2n5/1B1N2q1/3PpPPp/4n2K/PP2N3/R1BQ1R2 b kq g3 0 15")
         self.assertEqual(board.mirror(), mirrored)
+        board.apply_mirror()
+        self.assertEqual(board, mirrored)
 
     def test_chess960_pos(self):
         board = chess.Board()