BlackMali / StateMachine

Simple state machine implemented in C# (.net Standard 2.0, .net 8) with DI and async support

StateMachine

State machine implementation in C#.

Advantages:

• DI ready
• Async Pattern
• Safe programming with nullable types
• Works without constants and enums
• Builder for state machine creation
• Configuration of states and transitions
• Strict (default) and open transitions
• more than 95% code coverage

Compatible target frameworks

Product	Version
.NET Framework	.net 4.6.x .net 4.7.x .net 4.8.x
.NET Standard	.net standard 2.x
.NET Core	.net Core app 2.x .net core app 3.x
.NET	.net 5 .net 6 .net 7 .net 8

NuGet

You should install BlackMali.StateMachine with NuGet:

Install-Package BlackMali.StateMachine.Autofac

Or via the .NET Core command line interface:

dotnet add package BlackMali.StateMachine.Autofac

Registration

Autofac

var builder = new ContainerBuilder();
builder.RegisterModule<StateMachineModule>();
builder.RegisterType<LockState>().AsSelf();

Configuration

public class SlotMachine
{
	private readonly IStateMachine _stateMachine;

	public SlotMachine(IStateMachineBuilder builder)
	{
		// With DI registration -> AddState<LockState>()
		builder.AddState<LockState>()
			.AddStartTransition();
			.AddInStateTransition()
			.AddTransition<UnLockState>()
			.AddTransition<EndState>();

		// Without DI registration -> AddState(new UnLockState())
		builder.AddState(new UnLockState())
			.AddInStateTransition()
			.AddTransition<LockState>()
			.AddTransition<EndState>();

		// Create state machine
		_stateMachine = builder.Build();
	}
}

State change

// Perform state change
await _stateMachine.Transmit<LockState>();

// Or with Event
await _stateMachine.Transmit<LockState>(new StateMachineEvent());

// Or safe with exception handling
_stateMachine.OnError += (sender, args) => { };
await _stateMachine.TryTransmit<LockState>(new StateMachineEvent());

Event publishing with Post

// Posts an event to the current status
await _stateMachine.Post(new StateMachineEvent());

// Safe posting
await _stateMachine.TryPost(new StateMachineEvent());

State implementation

internal class LockState 
	: State // you can also use the interface IState without overrides
{
	// optional:
	public override async Task OnEnter(IStateMachineContext context)
	{
		await base.OnEnter(context);

		Console.WriteLine("Please insert coin");
	}

	// optional:
	public override async Task<IState?> OnTransmitted(IStateMachineContext context, StateMachineEvent @event)
	{
		var unLockEvent = @event as UnLockEvent;
		if (unLockEvent == null)
			return null;

		// No state change...
		if (unLockEvent.Coin == null)
			return null;

		// State change to UnLockState
		return await context.GetState<UnLockState>();
	}

	// optional:
	public override async Task OnExit(IStateMachineContext context)
	{
		// Do something...

		await Task.CompletedTask;
	}
}

Solution Packages

Package	Dependencies
BlackMali.StateMachine	No
BlackMali.StateMachine.Autofac	Autofac

Unit-Tests:

• XUnit
• XUnit.Runner.VisualStudio
• Autofac.Extras.Moq
• Moq
• Coverlet.Collector

IDE

Implemented with Microsoft Visual Studio Community 2022

• Markdown Editor
• Fine Code Coverage