// (C) Copyright 2015 Moodle Pty Ltd. // // 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 { Injector, Type } from '@angular/core'; /** * Stub class used to type anonymous classes created in CoreSingletonsFactory#makeSingleton method. */ class CoreSingleton {} /** * Token that can be used to resolve instances from the injector. */ export type CoreInjectionToken = Type | Type | string; /** * Singleton class created using the factory. */ export type CoreSingletonClass = typeof CoreSingleton & { instance: Service; setInstance(instance: Service): void; }; /** * Factory used to create CoreSingleton classes that get instances from an injector. */ export class CoreSingletonsFactory { /** * Angular injector used to resolve singleton instances. */ private injector: Injector; /** * Set the injector that will be used to resolve instances in the singletons created with this factory. * * @param injector Injector. */ setInjector(injector: Injector): void { this.injector = injector; } /** * Make a singleton that will hold an instance resolved from the factory injector. * * @param injectionToken Injection token used to resolve the singleton instance. This is usually the service class if the * provider was defined using a class or the string used in the `provide` key if it was defined using an object. */ makeSingleton(injectionToken: CoreInjectionToken): CoreSingletonClass { // eslint-disable-next-line @typescript-eslint/no-this-alias const factory = this; return class { private static serviceInstance: Service; static get instance(): Service { // Initialize instances lazily. if (!this.serviceInstance) { this.serviceInstance = factory.injector.get(injectionToken); } return this.serviceInstance; } static setInstance(instance: Service): void { this.serviceInstance = instance; } }; } }