core-api: added ApiFactoryRegistry

packages/core-api/src/apis/ApiFactoryRegistry.test.ts

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2020 Spotify AB
+ *
+ * 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 { ApiFactoryRegistry } from './ApiFactoryRegistry';
+import { createApiRef } from './ApiRef';
+
+const aRef = createApiRef<number>({ id: 'a', description: '' });
+const aFactory1 = { implements: aRef, deps: {}, factory: () => 1 };
+const aFactory2 = { implements: aRef, deps: {}, factory: () => 2 };
+const bRef = createApiRef<string>({ id: 'b', description: '' });
+const bFactory = { implements: bRef, deps: {}, factory: () => 'x' };
+const cRef = createApiRef<string>({ id: 'c', description: '' });
+const cFactory = { implements: cRef, deps: {}, factory: () => 'y' };
+
+describe('ApiFactoryRegistry', () => {
+  it('should be empty when created', () => {
+    const registry = new ApiFactoryRegistry();
+    expect(registry.getAllApis()).toEqual(new Set());
+  });
+
+  it('should register a factory', () => {
+    const registry = new ApiFactoryRegistry();
+    expect(registry.register('default', aFactory1)).toBe(true);
+    expect(registry.get(aRef)).toBe(aFactory1);
+    expect(registry.getAllApis()).toEqual(new Set([aRef]));
+  });
+
+  it('should prioritize factories based on scope', () => {
+    const registry = new ApiFactoryRegistry();
+    expect(registry.register('default', aFactory1)).toBe(true);
+    expect(registry.get(aRef)).toBe(aFactory1);
+    expect(registry.register('app', aFactory2)).toBe(true);
+    expect(registry.get(aRef)).toBe(aFactory2);
+    expect(registry.register('default', aFactory1)).toBe(false);
+    expect(registry.get(aRef)).toBe(aFactory2);
+    expect(registry.register('static', aFactory1)).toBe(true);
+    expect(registry.get(aRef)).toBe(aFactory1);
+    expect(registry.register('app', aFactory2)).toBe(false);
+    expect(registry.get(aRef)).toBe(aFactory1);
+    expect(registry.getAllApis()).toEqual(new Set([aRef]));
+  });
+
+  it('should register multiple factories without conflict', () => {
+    const registry = new ApiFactoryRegistry();
+    expect(registry.register('static', aFactory1)).toBe(true);
+    expect(registry.register('default', bFactory)).toBe(true);
+    expect(registry.register('app', cFactory)).toBe(true);
+    expect(registry.get(aRef)).toBe(aFactory1);
+    expect(registry.get(bRef)).toBe(bFactory);
+    expect(registry.get(cRef)).toBe(cFactory);
+    expect(registry.getAllApis()).toEqual(new Set([aRef, bRef, cRef]));
+  });
+});

packages/core-api/src/apis/ApiFactoryRegistry.ts

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2020 Spotify AB
+ *
+ * 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 {
+  ApiFactoryHolder,
+  ApiFactory,
+  AnyApiRef,
+  AnyApiFactory,
+} from './types';
+import { ApiRef } from './ApiRef';
+
+type ApiFactoryScope =
+  | 'default' // Default factories registered by core and plugins
+  | 'app' // Factories registered in the app, overriding default ones
+  | 'static'; // APIs that can't be overridden, e.g. config
+
+enum ScopeLevels {
+  default = 10,
+  app = 50,
+  static = 100,
+}
+
+type FactoryTuple = {
+  level: number;
+  factory: AnyApiFactory;
+};
+
+export class ApiFactoryRegistry implements ApiFactoryHolder {
+  private readonly factories = new Map<AnyApiRef, FactoryTuple>();
+
+  register<Api, Impl, Deps extends { [name in string]: unknown }>(
+    scope: ApiFactoryScope,
+    factory: ApiFactory<Api, Impl, Deps>,
+  ) {
+    const level = ScopeLevels[scope];
+    const existing = this.factories.get(factory.implements);
+    if (existing && existing.level > level) {
+      return false;
+    }
+
+    this.factories.set(factory.implements, { level, factory });
+    return true;
+  }
+
+  get<T>(
+    api: ApiRef<T>,
+  ): ApiFactory<T, T, { [x: string]: unknown }> | undefined {
+    const tuple = this.factories.get(api);
+    if (!tuple) {
+      return undefined;
+    }
+    return tuple.factory as ApiFactory<T, T, { [x: string]: unknown }>;
+  }
+
+  getAllApis(): Set<AnyApiRef> {
+    return new Set(this.factories.keys());
+  }
+}