docs/csharp/whats-new/tutorials/snippets/pattern-objects/CanalLock.cs - main - aprogrammer/dotnet-docs

docs/csharp/whats-new/tutorials/snippets/pattern-objects/CanalLock.cs

63 строки3 KB

Nick Schonning

fix: various typos outside samples/ (#32862)

05 дек 2022, 19:37

05 дек 2022, 19:37d1c3f9f

namespace pattern_objects;

public enum WaterLevel
{
    Low,
    High
}
public class CanalLock
{
    // Query canal lock state:
    public WaterLevel CanalLockWaterLevel { get; private set; } = WaterLevel.Low;
    public bool HighWaterGateOpen { get; private set; } = false;
    public bool LowWaterGateOpen { get; private set; } = false;

    // <FinalImplementation>
    // Change the upper gate.
    public void SetHighGate(bool open)
    {
        HighWaterGateOpen = (open, HighWaterGateOpen, CanalLockWaterLevel) switch
        {
            (false, _,    _)               => false,
            (true, _,     WaterLevel.High) => true,
            (true, false, WaterLevel.Low)  => throw new InvalidOperationException("Cannot open high gate when the water is low"),
            _                              => throw new InvalidOperationException("Invalid internal state"),
        };
    }
    // </FinalImplementation>

    // <FinalExercise>
    // Change the lower gate.
    public void SetLowGate(bool open)
    {
        LowWaterGateOpen = (open, LowWaterGateOpen, CanalLockWaterLevel) switch
        {
            (false, _, _) => false,
            (true, _, WaterLevel.Low) => true,
            (true, false, WaterLevel.High) => throw new InvalidOperationException("Cannot open high gate when the water is low"),
            _ => throw new InvalidOperationException("Invalid internal state"),
        };
    }

    // Change water level.
    public void SetWaterLevel(WaterLevel newLevel)
    {
        CanalLockWaterLevel = (newLevel, CanalLockWaterLevel, LowWaterGateOpen, HighWaterGateOpen) switch
        {
            (WaterLevel.Low, WaterLevel.Low, true, false) => WaterLevel.Low,
            (WaterLevel.High, WaterLevel.High, false, true) => WaterLevel.High,
            (WaterLevel.Low, _, false, false) => WaterLevel.Low,
            (WaterLevel.High, _, false, false) => WaterLevel.High,
            (WaterLevel.Low, WaterLevel.High, false, true) => throw new InvalidOperationException("Cannot lower water when the high gate is open"),
            (WaterLevel.High, WaterLevel.Low, true, false) => throw new InvalidOperationException("Cannot raise water when the low gate is open"),
            _ => throw new InvalidOperationException("Invalid internal state"),
        };
    }
    // </FinalExercise>


    public override string ToString() =>
        $"The lower gate is {(LowWaterGateOpen ? "Open" : "Closed")}. " +
        $"The upper gate is {(HighWaterGateOpen ? "Open" : "Closed")}. " +
        $"The water level is {CanalLockWaterLevel}.";
}