Async core refactor

src/Core/AsyncEvent/AsyncEventHandler.cs

@@ -0,0 +1,68 @@
+namespace AsyncEvent
+{
+    public class AsyncEventHandler<TSender, TArg> where TArg : AsyncEventArgs
+    {
+        private readonly List<Func<TSender, TArg, Task>> _handlers;
+        private readonly Action<Func<TSender, TArg, Task>> _add;
+        private readonly Action<Func<TSender, TArg, Task>> _remove;
+
+        public IReadOnlyList<Func<TSender, TArg, Task>> Handlers { get; }
+
+        public AsyncEventHandler(Action<Func<TSender, TArg, Task>>? add = null, Action<Func<TSender, TArg, Task>>? remove = null)
+        {
+            _handlers = new List<Func<TSender, TArg, Task>>();
+            Handlers = _handlers.AsReadOnly();
+            _add = add ?? AddInternal;
+            _remove = remove ?? RemoveInternal;
+        }
+
+        public void Add(Func<TSender, TArg, Task> handler)
+        {
+            _add.Invoke(handler);
+        }
+
+        public void Remove(Func<TSender, TArg, Task> handler)
+        {
+            _remove.Invoke(handler);
+        }
+
+        private void AddInternal(Func<TSender, TArg, Task> handler)
+        {
+            _handlers.Add(handler);
+        }
+
+        private void RemoveInternal(Func<TSender, TArg, Task> handler)
+        {
+            _handlers.Remove(handler);
+        }
+
+        public async Task InvokeAsync(TSender sender, TArg args)
+        {
+            foreach(var handler in _handlers)
+            {
+                await handler(sender, args);
+            }
+        }
+
+        public static AsyncEventHandler<TSender, TArg> operator +(AsyncEventHandler<TSender, TArg> obj, Func<TSender, TArg, Task> handler)
+        {
+            obj.Add(handler);
+            return obj;
+        }
+
+        public static AsyncEventHandler<TSender, TArg> operator -(AsyncEventHandler<TSender, TArg> obj, Func<TSender, TArg, Task> handler)
+        {
+            obj.Remove(handler);
+            return obj;
+        }
+    }
+    public class AsyncEventHandler<TArg> : AsyncEventHandler<object?, AsyncEventArgs> where TArg : AsyncEventArgs
+    {
+        public AsyncEventHandler(Action<Func<object?, TArg, Task>>? add = null, Action<Func<object?, TArg, Task>>? remove = null) : base(add, remove) { }
+    }
+
+    public class AsyncEventHandler : AsyncEventHandler<AsyncEventArgs>
+    {
+        public AsyncEventHandler(Action<Func<object?, AsyncEventArgs, Task>>? add = null, Action<Func<object?, AsyncEventArgs, Task>>? remove = null) : base(add, remove) { }
+    }
+}