change: Refactor AllVoidCompositeHandler into SequenceHandler.

src/util/SequenceHandler.ts

@@ -0,0 +1,32 @@
+import { AsyncHandler } from './AsyncHandler';
+
+/**
+ * A composite handler that will try to run all supporting handlers sequentially
+ * and return the value of the last supported handler.
+ * The `canHandle` check of this handler will always succeed.
+ */
+export class SequenceHandler<TIn = void, TOut = void> extends AsyncHandler<TIn, TOut | undefined> {
+  private readonly handlers: AsyncHandler<TIn, TOut>[];
+
+  public constructor(handlers: AsyncHandler<TIn, TOut>[]) {
+    super();
+    this.handlers = [ ...handlers ];
+  }
+
+  public async handle(input: TIn): Promise<TOut | undefined> {
+    let result: TOut | undefined;
+    for (const handler of this.handlers) {
+      let supported: boolean;
+      try {
+        await handler.canHandle(input);
+        supported = true;
+      } catch {
+        supported = false;
+      }
+      if (supported) {
+        result = await handler.handle(input);
+      }
+    }
+    return result;
+  }
+}