@quick-game/cli
Version:
Command line interface for rapid qg development
75 lines • 2.5 kB
JavaScript
// Copyright 2021 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
/**
* A class that facilitates resolving a id to an object of type T. If the id does not yet resolve, a promise
* is created that gets resolved once `onResolve` is called with the corresponding id.
*
* This class enables clients to control the duration of the wait and the lifetime of the associated
* promises by using the `clear` method on this class.
*/
export class ResolverBase {
#unresolvedIds = new Map();
/**
* Returns a promise that resolves once the `id` can be resolved to an object.
*/
async waitFor(id) {
const obj = this.getForId(id);
if (!obj) {
return this.getOrCreatePromise(id);
}
return obj;
}
/**
* Resolve the `id`. Returns the object immediatelly if it can be resolved,
* and otherwise waits for the object to appear and calls `callback` once
* it is resolved.
*/
tryGet(id, callback) {
const obj = this.getForId(id);
if (!obj) {
const swallowTheError = () => { };
void this.getOrCreatePromise(id).catch(swallowTheError).then(obj => {
if (obj) {
callback(obj);
}
});
return null;
}
return obj;
}
/**
* Aborts all waiting and rejects all unresolved promises.
*/
clear() {
this.stopListening();
for (const [id, { reject }] of this.#unresolvedIds.entries()) {
reject(new Error(`Object with ${id} never resolved.`));
}
this.#unresolvedIds.clear();
}
getOrCreatePromise(id) {
const promiseInfo = this.#unresolvedIds.get(id);
if (promiseInfo) {
return promiseInfo.promise;
}
let resolve = () => { };
let reject = () => { };
const promise = new Promise((res, rej) => {
resolve = res;
reject = rej;
});
this.#unresolvedIds.set(id, { promise, resolve, reject });
this.startListening();
return promise;
}
onResolve(id, t) {
const promiseInfo = this.#unresolvedIds.get(id);
this.#unresolvedIds.delete(id);
if (this.#unresolvedIds.size === 0) {
this.stopListening();
}
promiseInfo?.resolve(t);
}
}
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