Add skeleton classes Chess and Move

unitary/examples/quantum_chinese_chess/chess.py

@@ -0,0 +1,137 @@
+# Copyright 2023 The Unitary Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from unitary.examples.quantum_chinese_chess.board import Board
+from unitary.examples.quantum_chinese_chess.enums import Language
+from unitary.examples.quantum_chinese_chess.move import Move, get_move_from_string
+
+# List of accepable commands.
+_HELP_TEXT = """
+    Each location on the board is represented by two characters [abcdefghi][0-9], i.e. from a0 to i9. You may input (s=source, t=target)
+    - s1t1 to do a slide move, e.g. "a1a4"; 
+    - s1^t1t2 to do a split move, e.g. "a1^b1a2";
+    - s1s2^t1 to do a merge move, e.g. "b1a2^a1";
+    Other commands:
+    - "exit" to quit
+    - "help": to see this message again
+"""
+
+
+class QuantumChineseChess:
+    """A class that implements Quantum Chinese Chess using the unitary API."""
+
+    def __init__(self):
+        self.players_name = []
+        self.print_welcome()
+        self.board = Board.from_fen()
+        self.board.set_language(self.lang)
+        print(self.board)
+        self.player_quit = -1
+        self.current_player = self.board.current_player
+        self.debug_level = 3
+
+    def game_over(self) -> int:
+        """
+        Checks if the game is over.
+        Output:
+            -1: game continues
+             0: player 0 wins
+             1: player 1 wins
+             2: draw
+        """
+        # The other player wins if the current player quits.
+        if self.player_quit > -1:
+            return 1 - self.player_quit
+        return -1
+        # TODO(): add the following checks
+        # - The current player wins if general is captured in the current move.
+        # - The other player wins if the flying general rule is satisfied, i.e. there is no piece
+        # (after measurement) between two generals.
+        # - If player 0 made N repeatd back-and_forth moves in a row.
+
+    def get_move(self) -> Move:
+        """Check if the player wants to exit or needs help message. Otherwise parse and return the move."""
+        input_str = input(
+            f"\nIt is {self.players_name[self.current_player]}'s turn to move: "
+        )
+        if input_str.lower() == "help":
+            print(_HELP_TEXT)
+            raise ValueError("")
+        if input_str.lower() == "exit":
+            self.player_quit = self.current_player
+            raise ValueError("Exiting.")
+        try:
+            move = get_move_from_string(input_str.lower(), self.board)
+            return move
+        except ValueError as e:
+            raise e
+
+    def play(self) -> None:
+        """The loop where each player takes turn to play."""
+        while True:
+            try:
+                move = self.get_move()
+                print(move.to_str(self.debug_level))
+                # TODO(): apply the move.
+                print(self.board)
+            except ValueError as e:
+                print(e)
+                # Continue if the player does not quit.
+                if self.player_quit == -1:
+                    print("\nPlease re-enter your move.")
+                    continue
+            # Check if the game is over.
+            game_over = self.game_over()
+            # If the game continues, switch the player.
+            if game_over == -1:
+                self.current_player = 1 - self.current_player
+                self.board.current_player = self.current_player
+                continue
+            elif game_over == 0:
+                print(f"{self.players_name[0]} wins! Game is over.")
+            elif game_over == 1:
+                print(f"{self.players_name[1]} wins! Game is over.")
+            elif game_over == 2:
+                print("Draw! Game is over.")
+            break
+
+    def print_welcome(self) -> None:
+        """
+        Prints the welcome message. Gets board language and players' name.
+        """
+        welcome_message = """
+        Welcome to Quantum Chinese Chess!
+        """
+        print(welcome_message)
+        print(_HELP_TEXT)
+        # TODO(): add whole set of Chinese interface support.
+        lang = input(
+            "Switch to Chinese board characters? (y/n) (default to be English)  "
+        )
+        if lang.lower() == "y":
+            self.lang = Language.ZH
+        else:
+            self.lang = Language.EN
+        name_0 = input("Player 0's name (default to be Player_0):  ")
+        self.players_name.append("Player_0" if len(name_0) == 0 else name_0)
+        name_1 = input("Player 1's name (default to be Player_1):  ")
+        self.players_name.append("Player_1" if len(name_1) == 0 else name_1)
+
+
+def main():
+    game = QuantumChineseChess()
+    game.play()
+
+
+if __name__ == "__main__":
+    main()

unitary/examples/quantum_chinese_chess/chess_test.py

@@ -0,0 +1,43 @@
+# Copyright 2023 The Unitary Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+import mock
+import io
+import sys
+from unitary.examples.quantum_chinese_chess.chess import QuantumChineseChess
+from unitary.examples.quantum_chinese_chess.enums import Language
+
+
+def test_game_init():
+    output = io.StringIO()
+    sys.stdout = output
+    with mock.patch("builtins.input", side_effect=["y", "Bob", "Ben"]):
+        game = QuantumChineseChess()
+        assert game.lang == Language.ZH
+        assert game.players_name == ["Bob", "Ben"]
+        assert game.current_player == 0
+        assert "Welcome" in output.getvalue()
+    sys.stdout = sys.__stdout__
+
+
+def test_game_invalid_move():
+    output = io.StringIO()
+    sys.stdout = output
+    with mock.patch("builtins.input", side_effect=["y", "Bob", "Ben", "a1n1", "exit"]):
+        game = QuantumChineseChess()
+        game.play()
+        assert (
+            "Invalid location string. Make sure they are from a0 to i9."
+            in output.getvalue()
+        )
+    sys.stdout = sys.__stdout__

unitary/examples/quantum_chinese_chess/enums.py

@@ -48,9 +48,9 @@ class MoveVariant(enum.Enum):
 
 
 class Color(enum.Enum):
-    NA = 0
-    RED = 1
-    BLACK = 2
+    NA = -1
+    RED = 0
+    BLACK = 1
 
 
 class Type(enum.Enum):

unitary/examples/quantum_chinese_chess/move.py

@@ -0,0 +1,177 @@
+# Copyright 2023 The Unitary Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from typing import Optional, List, Tuple
+from unitary.alpha.quantum_effect import QuantumEffect
+from unitary.examples.quantum_chinese_chess.board import Board
+from unitary.examples.quantum_chinese_chess.enums import MoveType, MoveVariant, Type
+
+
+def parse_input_string(str_to_parse: str) -> Tuple[List[str], List[str]]:
+    """Check if the input string could be turned into a valid move.
+    Returns the sources and targets if it is valid.
+    The input needs to be:
+        - s1t1 for slide/jump move; or
+        - s1^t1t2 for split moves; or
+        - s1s2^t1 for merge moves.
+    Examples:
+       'a1a2'
+       'b1^a3c3'
+       'a3b1^c3'
+    """
+    sources = None
+    targets = None
+
+    if "^" in str_to_parse:
+        sources_str, targets_str = str_to_parse.split("^", maxsplit=1)
+        # The only two allowed cases here are s1^t1t2 and s1s2^t1.
+        if (
+            str_to_parse.count("^") > 1
+            or len(str_to_parse) != 7
+            or len(sources_str) not in [2, 4]
+        ):
+            raise ValueError(f"Invalid sources/targets string {str_to_parse}.")
+        sources = [sources_str[i : i + 2] for i in range(0, len(sources_str), 2)]
+        targets = [targets_str[i : i + 2] for i in range(0, len(targets_str), 2)]
+        if len(sources) == 2:
+            if sources[0] == sources[1]:
+                raise ValueError("Two sources should not be the same.")
+        elif targets[0] == targets[1]:
+            raise ValueError("Two targets should not be the same.")
+    else:
+        # The only allowed case here is s1t1.
+        if len(str_to_parse) != 4:
+            raise ValueError(f"Invalid sources/targets string {str_to_parse}.")
+        sources = [str_to_parse[0:2]]
+        targets = [str_to_parse[2:4]]
+        if sources[0] == targets[0]:
+            raise ValueError("Source and target should not be the same.")
+
+    # Make sure all the locations are valid.
+    for location in sources + targets:
+        if location[0].lower() not in "abcdefghi" or not location[1].isdigit():
+            raise ValueError(
+                f"Invalid location string. Make sure they are from a0 to i9."
+            )
+    return sources, targets
+
+
+def get_move_from_string(str_to_parse: str, board: Board) -> "Move":
+    """Check if the input string is valid. If it is, determine the move type and variant and return the move."""
+    try:
+        sources, targets = parse_input_string(str_to_parse)
+    except ValueError as e:
+        raise e
+    # Additional checks based on the current board.
+    for source in sources:
+        if board.board[source].type_ == Type.EMPTY:
+            raise ValueError("Could not move empty piece.")
+        if board.board[source].color.value != board.current_player:
+            raise ValueError("Could not move the other player's piece.")
+    # TODO(): add analysis to determine move type and variant.
+    move_type = MoveType.UNSPECIFIED_STANDARD
+    move_variant = MoveVariant.UNSPECIFIED
+    return Move(
+        sources[0],
+        targets[0],
+        board=board,
+        move_type=move_type,
+        move_variant=move_variant,
+    )
+
+
+class Move(QuantumEffect):
+    """The base class of all chess moves."""
+
+    def __init__(
+        self,
+        source: str,
+        target: str,
+        board: Board,
+        source2: Optional[str] = None,
+        target2: Optional[str] = None,
+        move_type: Optional[MoveType] = None,
+        move_variant: Optional[MoveVariant] = None,
+    ):
+        self.source = source
+        self.source2 = source2
+        self.target = target
+        self.target2 = target2
+        self.move_type = move_type
+        self.move_variant = move_variant
+        self.board = board
+
+    def __eq__(self, other):
+        if isinstance(other, Move):
+            return (
+                self.source == other.source
+                and self.source2 == other.source2
+                and self.target == other.target
+                and self.target2 == other.target2
+                and self.move_type == other.move_type
+                and self.move_variant == other.move_variant
+            )
+        return False
+
+    def _verify_objects(self, *objects):
+        # TODO(): add checks that apply to all move types
+        return
+
+    def effect(self, *objects):
+        # TODO(): add effects according to move_type and move_variant
+        return
+
+    def is_split_move(self) -> bool:
+        return self.target2 is not None
+
+    def is_merge_move(self) -> bool:
+        return self.source2 is not None
+
+    def to_str(self, verbose_level: int = 1) -> str:
+        """
+        Constructs the string representation of the move.
+        According to the value of verbose_level:
+        - 1: only returns the move source(s) and target(s);
+        - 2: additionally returns the move type and variant;
+        - 3: additionally returns the source(s) and target(s) piece type and color.
+        """
+        if verbose_level < 1:
+            return ""
+
+        if self.is_split_move():
+            move_str = [self.source + "^" + self.target + str(self.target2)]
+        elif self.is_merge_move():
+            move_str = [self.source + str(self.source2) + "^" + self.target]
+        else:
+            move_str = [self.source + self.target]
+
+        if verbose_level > 1:
+            move_str.append(self.move_type.name)
+            move_str.append(self.move_variant.name)
+
+        if verbose_level > 2:
+            source = self.board.board[self.source]
+            target = self.board.board[self.target]
+            move_str.append(
+                source.color.name
+                + "_"
+                + source.type_.name
+                + "->"
+                + target.color.name
+                + "_"
+                + target.type_.name
+            )
+        return ":".join(move_str)
+
+    def __str__(self):
+        return self.to_str()