feat: version 2 beta

libraries/event-factory.ts

@@ -0,0 +1,53 @@
+import { Event } from "./event.ts";
+
+/**
+ * Indexes a list of event factories for use with aggregates and event stores
+ * when generating or accessing event functionality.
+ *
+ * @example
+ *
+ * ```ts
+ * import { event } from "@valkyr/event-store";
+ * import z from "zod";
+ *
+ * const factory = new EventFactory([
+ *   event
+ *     .type("user:created")
+ *     .data(z.object({ name: z.string(), email: z.email() }))
+ *     .meta(z.object({ createdBy: z.string() })),
+ * ]);
+ *
+ * export type Events = typeof factory.$events;
+ * ```
+ */
+export class EventFactory<const TEvents extends Event[] = Event[]> {
+  /**
+   * Optimized event lookup index.
+   */
+  readonly #index = new Map<TEvents[number]["state"]["type"], TEvents[number]>();
+
+  /**
+   * Inferred type of the events registered with the factory.
+   */
+  declare readonly $events: TEvents;
+
+  /**
+   * Instantiate a new EventFactory with given list of supported events.
+   *
+   * @param events - Events to register with the factory.
+   */
+  constructor(readonly events: TEvents) {
+    for (const event of events) {
+      this.#index.set(event.state.type, event);
+    }
+  }
+
+  /**
+   * Get a registered event from the factory.
+   *
+   * @param type - Event type to retrieve.
+   */
+  get<TType extends TEvents[number]["state"]["type"]>(type: TType): Extract<TEvents[number], { state: { type: TType } }> {
+    return this.#index.get(type) as Extract<TEvents[number], { state: { type: TType } }>;
+  }
+}