/** * Copyright 2022 Google Inc. All rights reserved. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ import {assert} from '../util/assert.js'; import {createDeferred, Deferred} from '../util/Deferred.js'; /** * @internal */ export interface Poller { start(): Promise; stop(): Promise; result(): Promise; } /** * @internal */ export class MutationPoller implements Poller { #fn: () => Promise; #root: Node; #observer?: MutationObserver; #deferred?: Deferred; constructor(fn: () => Promise, root: Node) { this.#fn = fn; this.#root = root; } async start(): Promise { const deferred = (this.#deferred = createDeferred()); const result = await this.#fn(); if (result) { deferred.resolve(result); return; } this.#observer = new MutationObserver(async () => { const result = await this.#fn(); if (!result) { return; } deferred.resolve(result); await this.stop(); }); this.#observer.observe(this.#root, { childList: true, subtree: true, attributes: true, }); } async stop(): Promise { assert(this.#deferred, 'Polling never started.'); if (!this.#deferred.finished()) { this.#deferred.reject(new Error('Polling stopped')); } if (this.#observer) { this.#observer.disconnect(); this.#observer = undefined; } } result(): Promise { assert(this.#deferred, 'Polling never started.'); return this.#deferred.valueOrThrow(); } } /** * @internal */ export class RAFPoller implements Poller { #fn: () => Promise; #deferred?: Deferred; constructor(fn: () => Promise) { this.#fn = fn; } async start(): Promise { const deferred = (this.#deferred = createDeferred()); const result = await this.#fn(); if (result) { deferred.resolve(result); return; } const poll = async () => { if (deferred.finished()) { return; } const result = await this.#fn(); if (!result) { window.requestAnimationFrame(poll); return; } deferred.resolve(result); await this.stop(); }; window.requestAnimationFrame(poll); } async stop(): Promise { assert(this.#deferred, 'Polling never started.'); if (!this.#deferred.finished()) { this.#deferred.reject(new Error('Polling stopped')); } } result(): Promise { assert(this.#deferred, 'Polling never started.'); return this.#deferred.valueOrThrow(); } } /** * @internal */ export class IntervalPoller implements Poller { #fn: () => Promise; #ms: number; #interval?: NodeJS.Timer; #deferred?: Deferred; constructor(fn: () => Promise, ms: number) { this.#fn = fn; this.#ms = ms; } async start(): Promise { const deferred = (this.#deferred = createDeferred()); const result = await this.#fn(); if (result) { deferred.resolve(result); return; } this.#interval = setInterval(async () => { const result = await this.#fn(); if (!result) { return; } deferred.resolve(result); await this.stop(); }, this.#ms); } async stop(): Promise { assert(this.#deferred, 'Polling never started.'); if (!this.#deferred.finished()) { this.#deferred.reject(new Error('Polling stopped')); } if (this.#interval) { clearInterval(this.#interval); this.#interval = undefined; } } result(): Promise { assert(this.#deferred, 'Polling never started.'); return this.#deferred.valueOrThrow(); } }