MOBILE-3320 core: Refactor singletons definition

src/core/classes/singletons-factory.ts

@@ -1,88 +0,0 @@
-// (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<Service> = Type<Service> | Type<unknown> | string;
-
-/**
- * Singleton class created using the factory.
- */
-export type CoreSingletonClass<Service> = 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<Service>(injectionToken: CoreInjectionToken<Service>): CoreSingletonClass<Service> {
-        // 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) {
-                    if (!factory.injector) {
-                        throw new Error('Can\'t resolve a singleton instance without an injector');
-                    }
-
-                    this.serviceInstance = factory.injector.get(injectionToken);
-                }
-
-                return this.serviceInstance;
-            }
-
-            static setInstance(instance: Service): void {
-                this.serviceInstance = instance;
-            }
-
-        };
-    }
-
-}

src/core/singletons/index.ts

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-import { ApplicationRef, ApplicationInitStatus, Injector, NgZone as NgZoneService } from '@angular/core';
+import { ApplicationRef, ApplicationInitStatus, Injector, NgZone as NgZoneService, Type } from '@angular/core';
 import { HttpClient } from '@angular/common/http';
 
 import {
@@ -52,9 +52,23 @@ import { Zip as ZipService } from '@ionic-native/zip/ngx';
 
 import { TranslateService } from '@ngx-translate/core';
 
-import { CoreSingletonsFactory, CoreInjectionToken, CoreSingletonClass } from '@classes/singletons-factory';
+/**
+ * Injector instance used to resolve singletons.
+ */
+let singletonsInjector: Injector | null = null;
 
-const factory = new CoreSingletonsFactory();
+/**
+ * Stub class used to type anonymous classes created in the makeSingleton method.
+ */
+class CoreSingleton {}
+
+/**
+ * Singleton class created using the factory.
+ */
+export type CoreSingletonClass<Service> = typeof CoreSingleton & {
+    instance: Service;
+    setInstance(instance: Service): void;
+};
 
 /**
  * Set the injector that will be used to resolve instances in the singletons of this module.
@@ -62,17 +76,38 @@ const factory = new CoreSingletonsFactory();
  * @param injector Module injector.
  */
 export function setSingletonsInjector(injector: Injector): void {
-    factory.setInjector(injector);
+    singletonsInjector = injector;
 }
 
 /**
- * Make a singleton for this module.
+ * Make a singleton for the given injection token.
  *
  * @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.
  */
-export function makeSingleton<Service>(injectionToken: CoreInjectionToken<Service>): CoreSingletonClass<Service> {
+export function makeSingleton<Service>(injectionToken: Type<Service> | Type<unknown> | string): CoreSingletonClass<Service> {
-    return factory.makeSingleton(injectionToken);
+    return class {
+
+        private static serviceInstance: Service;
+
+        static get instance(): Service {
+            // Initialize instances lazily.
+            if (!this.serviceInstance) {
+                if (!singletonsInjector) {
+                    throw new Error('Can\'t resolve a singleton instance without an injector');
+                }
+
+                this.serviceInstance = singletonsInjector.get(injectionToken);
+            }
+
+            return this.serviceInstance;
+        }
+
+        static setInstance(instance: Service): void {
+            this.serviceInstance = instance;
+        }
+
+    };
 }
 
 // Convert ionic-native services to singleton.

src/testing/utils.ts

@@ -15,7 +15,7 @@
 import { Component, CUSTOM_ELEMENTS_SCHEMA, Type, ViewChild } from '@angular/core';
 import { ComponentFixture, TestBed } from '@angular/core/testing';
 
-import { CoreSingletonClass } from '@classes/singletons-factory';
+import { CoreSingletonClass } from '@singletons';
 
 abstract class WrapperComponent<U> {