Make Transition Actions Async-First

Pull request dotnet-state-machine#452

Author: Pentiva

Diff for: src/Stateless/ActivateActionBehaviour.cs

@@ -4,63 +4,34 @@ namespace Stateless;
 
 public partial class StateMachine<TState, TTrigger>
 {
-    internal abstract class ActivateActionBehaviour
+    internal class ActivateActionBehaviour
     {
-        private readonly TState _state;
+        private readonly TState        _state;
 
-        private ActivateActionBehaviour(TState state, InvocationInfo actionDescription)
-        {
-            _state      = state;
-            Description = actionDescription ?? throw new ArgumentNullException(nameof(actionDescription));
-        }
+        private readonly EventCallback _callback = EventCallbackFactory.Empty;
 
         internal InvocationInfo Description { get; }
 
-        public abstract void Execute();
-        public abstract Task ExecuteAsync();
+        public ActivateActionBehaviour(TState state, Action action, InvocationInfo actionDescription)
+            : this(state, actionDescription) {
+            _callback   = EventCallbackFactory.Create(action);
+        }
 
-        public class Sync : ActivateActionBehaviour
+        public ActivateActionBehaviour(TState state, Func<Task> action, InvocationInfo actionDescription)
+            : this(state, actionDescription)
         {
-            private readonly Action _action;
-
-            public Sync(TState state, Action action, InvocationInfo actionDescription)
-                : base(state, actionDescription)
-            {
-                _action = action;
-            }
-
-            public override void Execute()
-            {
-                _action();
-            }
-
-            public override Task ExecuteAsync()
-            {
-                Execute();
-                return TaskResult.Done;
-            }
+            _callback = EventCallbackFactory.Create(action);
         }
 
-        public class Async : ActivateActionBehaviour
+        protected ActivateActionBehaviour(TState state, InvocationInfo actionDescription)
         {
-            private readonly Func<Task> _action;
-
-            public Async(TState state, Func<Task> action, InvocationInfo actionDescription)
-                : base(state, actionDescription)
-            {
-                _action = action;
-            }
-
-            public override void Execute()
-            {
-                throw new InvalidOperationException(
-                                                    $"Cannot execute asynchronous action specified in OnActivateAsync for '{_state}' state. Use asynchronous version of Activate [ActivateAsync]");
-            }
+            _state      = state;
+            Description = actionDescription ?? throw new ArgumentNullException(nameof(actionDescription));
+        }
 
-            public override Task ExecuteAsync()
-            {
-                return _action();
-            }
+        public virtual Task ExecuteAsync()
+        {
+            return _callback.InvokeAsync();
         }
     }
 }

Diff for: src/Stateless/DeactivateActionBehaviour.cs

@@ -4,63 +4,35 @@ namespace Stateless;
 
 public partial class StateMachine<TState, TTrigger>
 {
-    internal abstract class DeactivateActionBehaviour
+    internal class DeactivateActionBehaviour
     {
-        private readonly TState _state;
-
-        private DeactivateActionBehaviour(TState state, InvocationInfo actionDescription)
-        {
-            _state      = state;
-            Description = actionDescription ?? throw new ArgumentNullException(nameof(actionDescription));
-        }
+        private readonly TState         _state;
+        
+        private readonly EventCallback  _callback = EventCallbackFactory.Empty;
 
         internal InvocationInfo Description { get; }
 
-        public abstract void Execute();
-        public abstract Task ExecuteAsync();
+        public DeactivateActionBehaviour(TState state, Action action, InvocationInfo actionDescription)
+            : this(state, actionDescription) {
+            _callback = EventCallbackFactory.Create(action);
+        }
 
-        public class Sync : DeactivateActionBehaviour
+        public DeactivateActionBehaviour(TState state, Func<Task> action, InvocationInfo actionDescription)
+            : this(state, actionDescription)
         {
-            private readonly Action _action;
-
-            public Sync(TState state, Action action, InvocationInfo actionDescription)
-                : base(state, actionDescription)
-            {
-                _action = action;
-            }
-
-            public override void Execute()
-            {
-                _action();
-            }
-
-            public override Task ExecuteAsync()
-            {
-                Execute();
-                return TaskResult.Done;
-            }
+            _callback = EventCallbackFactory.Create(action);
         }
 
-        public class Async : DeactivateActionBehaviour
+        protected DeactivateActionBehaviour(TState state, InvocationInfo actionDescription)
         {
-            private readonly Func<Task> _action;
-
-            public Async(TState state, Func<Task> action, InvocationInfo actionDescription)
-                : base(state, actionDescription)
-            {
-                _action = action;
-            }
-
-            public override void Execute()
-            {
-                throw new InvalidOperationException(
-                                                    $"Cannot execute asynchronous action specified in OnDeactivateAsync for '{_state}' state. Use asynchronous version of Deactivate [DeactivateAsync]");
-            }
+            _state      = state;
+            Description = actionDescription ?? throw new ArgumentNullException(nameof(actionDescription));
+        }
 
-            public override Task ExecuteAsync()
-            {
-                return _action();
-            }
+        public virtual Task ExecuteAsync()
+        {
+            return _callback.InvokeAsync();
         }
+
     }
 }

Diff for: src/Stateless/EntryActionBehaviour.cs

@@ -4,81 +4,56 @@ namespace Stateless;
 
 public partial class StateMachine<TState, TTrigger>
 {
-    internal abstract class EntryActionBehavior
+    internal class EntryActionBehavior
     {
-        private EntryActionBehavior(InvocationInfo description)
+        private readonly EventCallback<Transition, object?[]> _callback = EventCallbackFactory.Create<Transition, object?[]>(delegate { });
+
+        public EntryActionBehavior(Action<Transition, object?[]> action, InvocationInfo description)
+            : this(description)
         {
-            Description = description;
+            _callback = EventCallbackFactory.Create(action);
         }
 
-        public InvocationInfo Description { get; }
-
-        public abstract void Execute(Transition      transition, object?[] args);
-        public abstract Task ExecuteAsync(Transition transition, object?[] args);
-
-        public class Sync : EntryActionBehavior
+        public EntryActionBehavior(Func<Transition, object?[], Task> action, InvocationInfo description)
+            : this(description)
         {
-            private readonly Action<Transition, object?[]> _action;
+            _callback = EventCallbackFactory.Create(action);
+        }
 
-            public Sync(Action<Transition, object?[]> action, InvocationInfo description) : base(description)
-            {
-                _action = action;
-            }
+        protected EntryActionBehavior(InvocationInfo description)
+        {
+            Description = description;
+        }
 
-            public override void Execute(Transition transition, object?[] args)
-            {
-                _action(transition, args);
-            }
+        public InvocationInfo Description { get; }
 
-            public override Task ExecuteAsync(Transition transition, object?[] args)
-            {
-                Execute(transition, args);
-                return TaskResult.Done;
-            }
+        public virtual Task ExecuteAsync(Transition transition, object?[] args)
+        {
+            return _callback.InvokeAsync(transition, args);
         }
 
-        public class SyncFrom<TTriggerType> : Sync
+        public class From<TTriggerType> : EntryActionBehavior
         {
             internal TTriggerType Trigger { get; }
 
-            public SyncFrom(TTriggerType trigger, Action<Transition, object?[]> action, InvocationInfo description)
+            public From(TTriggerType trigger, Action<Transition, object?[]> action, InvocationInfo description)
                 : base(action, description)
             {
                 Trigger = trigger;
             }
 
-            public override void Execute(Transition transition, object?[] args)
+            public From(TTriggerType trigger, Func<Transition, object?[], Task> action, InvocationInfo description)
+                : base(action, description)
             {
-                if (transition.Trigger.Equals(Trigger))
-                    base.Execute(transition, args);
+                Trigger = trigger;
             }
 
             public override Task ExecuteAsync(Transition transition, object?[] args)
             {
-                Execute(transition, args);
+                if (transition.Trigger.Equals(Trigger))
+                    return base.ExecuteAsync(transition, args);
                 return TaskResult.Done;
             }
         }
-
-        public class Async : EntryActionBehavior
-        {
-            private readonly Func<Transition, object?[], Task> _action;
-
-            public Async(Func<Transition, object?[], Task> action, InvocationInfo description) : base(description)
-            {
-                _action = action;
-            }
-
-            public override void Execute(Transition transition, object?[] args)
-            {
-                throw new InvalidOperationException(
-                                                    $"Cannot execute asynchronous action specified in OnEntry event for '{transition.Destination}' state. Use asynchronous version of Fire [FireAsync]");
-            }
-
-            public override Task ExecuteAsync(Transition transition, object?[] args)
-            {
-                return _action(transition, args);
-            }
-        }
     }
 }