null_object.py

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from abc import ABC, abstractmethod
 
 
class MoveCommand(ABC):
 
    
    def __init__(self, command : str, commandName : str) -> None:
        self._name = commandName
        self._command = command
 
    
 
 
    
    def Show(self) -> None:
        print("    '{0}' -> {1}".format(self._command, self._name))
 
 
    
    @abstractmethod
    def Execute(self) -> None:
        pass
 
 
 
 
 
 
class MoveCommandLeft(MoveCommand):
    
    def __init__(self, command : str) -> None:
        super().__init__(command, "Left")
 
 
    
    def Execute(self) -> None:
        print("move left", end="")
 
 
 
 
 
 
class MoveCommandRight(MoveCommand):
    
    def __init__(self, command : str) -> None:
        super().__init__(command, "Right")
 
 
    
    def Execute(self):
        print("move right", end="")
 
 
 
 
 
 
class MoveCommandUp(MoveCommand):
    
    def __init__(self, command : str) -> None :
       super().__init__(command, "Up")
 
 
    
    def Execute(self) -> None:
        print("move up", end="")
 
 
 
 
 
 
class MoveCommandDown(MoveCommand):
    
    def __init__(self, command : str) -> None:
       super().__init__(command, "Down")
 
 
    
    def Execute(self) -> None:
        print("move down", end="")
 
 
 
 
 
 
class MoveCommandNone(MoveCommand):
    
    def __init__(self, command: str) -> None:
       super().__init__(command, "None")
 
 
    
    def Execute(self) -> str:
        pass
 
 
 
 
 
 
class MoveProcessor:
 
   #++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    # Private methods.
 
    
    def _ParseMoves(self, moveList : str) -> list[MoveCommand]:
        commands = [] # type: list[MoveCommand]
        for index in range(0, len(moveList)):
            commandChar = moveList[index].upper()
            moveCommand = None
 
            match (commandChar):
                case 'U':
                    moveCommand = MoveCommandUp(commandChar)
 
                case 'D':
                    moveCommand = MoveCommandDown(commandChar)
 
                case 'L':
                    moveCommand = MoveCommandLeft(commandChar)
 
                case 'R':
                    moveCommand = MoveCommandRight(commandChar)
 
                case _:
                    # Everything else is a "do nothing" command.
                    moveCommand = MoveCommandNone(commandChar)
 
            commands.append(moveCommand);
 
        return commands;
 
 
    
    def _ExecuteMoves(self, commands : list[MoveCommand]) -> None:
        for command in commands:
            print("<", end="")
            command.Execute()
            print("> ", end="")
        print()
 
 
    
    def _ShowMoves(self, commands : list[MoveCommand]) -> None:
        for command in commands:
            command.Show()
            
 
    #++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    # Public methods.
 
    
    def ExecuteMoveList(self, moveList: str) -> None:
        commands = self._ParseMoves(moveList)
        self._ExecuteMoves(commands)
 
 
    
    def ShowMoveList(self, moveList : str) -> None:
        commands = self._ParseMoves(moveList)
        self._ShowMoves(commands)