Add Executor and RelaySet

lib/util/Deferred.ts

@@ -0,0 +1,14 @@
+export type Deferred<T> = Promise<T> & {
+  resolve: (arg: T) => void
+  reject: (arg: T) => void
+}
+
+export const defer = (): Deferred<any> => {
+  let resolve, reject
+  const p = new Promise((resolve_, reject_) => {
+    resolve = resolve_
+    reject = reject_
+  })
+
+  return Object.assign(p, {resolve, reject}) as any
+}

lib/util/EventBus.ts

@@ -0,0 +1,36 @@
+export type EventBusHandler = (...args: any[]) => void
+export type EventBusListener = {
+  id: string
+  handler: EventBusHandler
+}
+
+export class EventBus {
+  static ANY = Math.random().toString().slice(2)
+  listeners: Record<string, Array<EventBusListener>> = {}
+  on(name: string, handler: EventBusHandler) {
+    const id = Math.random().toString().slice(2)
+
+    this.listeners[name] = this.listeners[name] || ([] as Array<EventBusListener>)
+    this.listeners[name].push({id, handler})
+
+    return id
+  }
+  off(name: string, id: string) {
+    this.listeners[name] = this.listeners[name].filter(l => l.id !== id)
+  }
+  clear() {
+    this.listeners = {}
+  }
+  handle(k: string, ...payload: any) {
+    for (const {handler} of this.listeners[k] || []) {
+      handler(...payload)
+    }
+
+    for (const {handler} of this.listeners[EventBus.ANY] || []) {
+      handler(k, ...payload)
+    }
+  }
+  pipe(k: string, bus: EventBus) {
+    this.on(k, (...payload: any[]) => bus.handle(k, ...payload))
+  }
+}