Refactor streaming to use async iterators

src/subscription.ts

@@ -0,0 +1,46 @@
+import { type Event } from '@/deps.ts';
+import { matchDittoFilters } from '@/filter.ts';
+
+import type { DittoFilter, EventData } from '@/types.ts';
+
+class Subscription<K extends number = number> implements AsyncIterable<Event<K>> {
+  filters: DittoFilter<K>[];
+  #next?: (event: Event<K>) => void;
+  #closed = false;
+
+  constructor(filters: DittoFilter<K>[]) {
+    this.filters = filters;
+  }
+
+  stream(event: Event<K>): void {
+    if (this.#next) {
+      this.#next(event);
+      this.#next = undefined;
+    }
+  }
+
+  matches(event: Event, data: EventData): boolean {
+    return matchDittoFilters(this.filters, event, data);
+  }
+
+  close() {
+    this.#closed = true;
+    this.#next?.(undefined!);
+  }
+
+  async *[Symbol.asyncIterator]() {
+    while (true) {
+      const event = await new Promise<Event<K>>((resolve) => {
+        this.#next = resolve;
+      });
+
+      if (this.#closed) {
+        return;
+      }
+
+      yield event;
+    }
+  }
+}
+
+export { Subscription };