77 lines
2.4 KiB
TypeScript
77 lines
2.4 KiB
TypeScript
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// (C) Copyright 2015 Moodle Pty Ltd.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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import { Injector, Type } from '@angular/core';
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/**
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* Stub class used to type anonymous classes created in CoreSingletonsFactory#makeSingleton method.
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*/
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class CoreSingleton {}
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/**
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* Token that can be used to resolve instances from the injector.
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*/
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export type CoreInjectionToken<Service> = Type<Service> | Type<any> | string;
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/**
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* Singleton class created using the factory.
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*/
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export type CoreSingletonClass<Service> = typeof CoreSingleton & { instance: Service };
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/**
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* Factory used to create CoreSingleton classes that get instances from an injector.
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*/
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export class CoreSingletonsFactory {
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/**
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* Angular injector used to resolve singleton instances.
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*/
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private injector: Injector;
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/**
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* Set the injector that will be used to resolve instances in the singletons created with this factory.
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*
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* @param injector Injector.
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*/
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setInjector(injector: Injector): void {
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this.injector = injector;
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}
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/**
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* Make a singleton that will hold an instance resolved from the factory injector.
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*
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* @param injectionToken Injection token used to resolve the singleton instance. This is usually the service class if the
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* provider was defined using a class or the string used in the `provide` key if it was defined using an object.
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*/
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makeSingleton<Service>(injectionToken: CoreInjectionToken<Service>): CoreSingletonClass<Service> {
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// tslint:disable: no-this-assignment
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const factory = this;
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return class {
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private static _instance: Service;
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static get instance(): Service {
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// Initialize instances lazily.
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if (!this._instance) {
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this._instance = factory.injector.get(injectionToken);
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}
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return this._instance;
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}
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};
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}
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}
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