MAJOR RELEASEHEADprimary

- inlined vendored dependencies from npm
- makes this module work in Ende

1 files changed, 64 insertions, 0 deletions

diff --git a/source/utility/pubsub.ts b/source/utility/pubsub.ts
new file mode 100644
index 0000000..bb8679a
--- /dev/null
+++ b/source/utility/pubsub.ts
@@ -0,0 +1,64 @@
+export class PubSub {
+  #target = new EventTarget();
+
+  publish(trigger: string, payload: unknown): Promise<void> {
+    this.#target.dispatchEvent(new CustomEvent(trigger, { detail: payload }));
+    return Promise.resolve();
+  }
+
+  asyncIterator<T>(triggers: string | string[]): AsyncIterableIterator<T> {
+    const names = Array.isArray(triggers) ? triggers : [triggers];
+    const pulls: Array<(result: IteratorResult<T>) => void> = [];
+    const pushes: T[] = [];
+    let done = false;
+
+    const listener = (event: Event) => {
+      const value = (event as CustomEvent<T>).detail;
+      const pull = pulls.shift();
+
+      if (pull)
+        pull({ done: false, value });
+      else
+        pushes.push(value);
+    };
+
+    for (const name of names)
+      this.#target.addEventListener(name, listener);
+
+    const close = (): Promise<IteratorResult<T>> => {
+      if (!done) {
+        done = true;
+
+        for (const name of names)
+          this.#target.removeEventListener(name, listener);
+
+        for (const pull of pulls.splice(0))
+          pull({ done: true, value: undefined });
+
+        pushes.length = 0;
+      }
+
+      return Promise.resolve({ done: true, value: undefined });
+    };
+
+    return {
+      next: () => {
+        if (done)
+          return Promise.resolve({ done: true, value: undefined });
+
+        if (pushes.length > 0)
+          return Promise.resolve({ done: false, value: pushes.shift() as T });
+
+        return new Promise((resolve) => pulls.push(resolve));
+      },
+      return: close,
+      throw: (error: unknown) => {
+        close();
+        return Promise.reject(error);
+      },
+      [Symbol.asyncIterator]() {
+        return this;
+      }
+    };
+  }
+}