core-api: added ApiResolver
This commit is contained in:
Patrik Oldsberg
@@ -0,0 +1,177 @@
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/*
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* Copyright 2020 Spotify AB
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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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*/
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import { ApiResolver } from './ApiResolver';
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import { createApiRef } from './ApiRef';
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import { ApiFactoryRegistry } from './ApiFactoryRegistry';
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const aRef = createApiRef<number>({ id: 'a', description: '' });
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const bRef = createApiRef<string>({ id: 'b', description: '' });
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const cRef = createApiRef<{ x: string }>({ id: 'c', description: '' });
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function createRegistry() {
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const registry = new ApiFactoryRegistry();
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registry.register('default', {
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implements: aRef,
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deps: {},
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factory: () => 1,
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});
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registry.register('default', {
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implements: bRef,
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deps: {},
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factory: () => 'b',
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});
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registry.register('default', {
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implements: cRef,
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deps: { b: bRef },
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factory: ({ b }) => ({ x: 'x', b }),
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});
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return registry;
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}
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function createLongCyclicRegistry() {
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const registry = new ApiFactoryRegistry();
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registry.register('default', {
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implements: aRef,
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deps: { b: bRef },
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factory: () => 1,
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});
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registry.register('default', {
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implements: bRef,
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deps: { c: cRef },
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factory: () => 'b',
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});
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registry.register('default', {
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implements: cRef,
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deps: { a: aRef },
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factory: () => ({ x: 'x' }),
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});
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return registry;
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}
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function createShortCyclicRegistry() {
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const registry = new ApiFactoryRegistry();
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registry.register('default', {
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implements: aRef,
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deps: { a: aRef },
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factory: () => 1,
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});
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registry.register('default', {
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implements: bRef,
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deps: { c: cRef },
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factory: () => 'b',
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});
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registry.register('default', {
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implements: cRef,
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deps: { b: bRef },
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factory: () => ({ x: 'x' }),
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});
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return registry;
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}
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describe('ApiResolver', () => {
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it('should be created empty', () => {
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const resolver = new ApiResolver(new ApiFactoryRegistry());
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expect(resolver.get(aRef)).toBe(undefined);
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expect(resolver.get(bRef)).toBe(undefined);
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expect(resolver.get(cRef)).toBe(undefined);
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});
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it('should instantiate APIs', () => {
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const resolver = new ApiResolver(createRegistry());
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expect(resolver.get(aRef)).toBe(1);
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expect(resolver.get(bRef)).toBe('b');
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expect(resolver.get(cRef)).toEqual({ x: 'x', b: 'b' });
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expect(resolver.get(cRef)).toBe(resolver.get(cRef));
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});
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it('should detect long dependency cycles', () => {
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const resolver = new ApiResolver(createLongCyclicRegistry());
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expect(() => resolver.get(aRef)).toThrow(
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'Circular dependency of api factory for apiRef{a}',
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);
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// Second call for same ref should still throw
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expect(() => resolver.get(aRef)).toThrow(
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'Circular dependency of api factory for apiRef{a}',
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);
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expect(() => resolver.get(bRef)).toThrow(
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'Circular dependency of api factory for apiRef{b}',
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);
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expect(() => resolver.get(cRef)).toThrow(
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'Circular dependency of api factory for apiRef{c}',
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);
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});
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it('should detect short dependency cycles', () => {
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const resolver = new ApiResolver(createShortCyclicRegistry());
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expect(() => resolver.get(aRef)).toThrow(
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'Circular dependency of api factory for apiRef{a}',
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);
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expect(() => resolver.get(bRef)).toThrow(
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'Circular dependency of api factory for apiRef{b}',
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);
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expect(() => resolver.get(cRef)).toThrow(
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'Circular dependency of api factory for apiRef{c}',
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);
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});
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it('should validate a factory holder', () => {
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expect(() => {
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ApiResolver.validateFactories(createRegistry(), [aRef, bRef, cRef]);
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}).not.toThrow();
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});
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it('should find dependency cycles with validation', () => {
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const short = createShortCyclicRegistry();
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expect(() =>
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ApiResolver.validateFactories(short, short.getAllApis()),
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).toThrow('Circular dependency of api factory for apiRef{a}');
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expect(() => ApiResolver.validateFactories(short, [bRef])).toThrow(
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'Circular dependency of api factory for apiRef{b}',
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);
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expect(() => ApiResolver.validateFactories(short, [cRef])).toThrow(
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'Circular dependency of api factory for apiRef{c}',
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);
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const long = createLongCyclicRegistry();
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expect(() =>
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ApiResolver.validateFactories(long, long.getAllApis()),
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).toThrow('Circular dependency of api factory for apiRef{a}');
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expect(() => ApiResolver.validateFactories(long, [bRef])).toThrow(
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'Circular dependency of api factory for apiRef{b}',
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);
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expect(() => ApiResolver.validateFactories(long, [cRef])).toThrow(
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'Circular dependency of api factory for apiRef{c}',
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);
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});
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it('should only call factory func once', () => {
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const registry = new ApiFactoryRegistry();
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const factory = jest.fn().mockReturnValue(2);
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registry.register('default', {
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implements: aRef,
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deps: {},
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factory,
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});
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const resolver = new ApiResolver(registry);
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expect(factory).toHaveBeenCalledTimes(0);
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expect(resolver.get(aRef)).toBe(2);
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expect(factory).toHaveBeenCalledTimes(1);
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expect(resolver.get(aRef)).toBe(2);
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expect(factory).toHaveBeenCalledTimes(1);
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});
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});
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@@ -0,0 +1,115 @@
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/*
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* Copyright 2020 Spotify AB
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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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*/
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import { ApiRef } from './ApiRef';
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import {
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ApiHolder,
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ApiFactoryHolder,
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AnyApiRef,
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TypesToApiRefs,
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} from './types';
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export class ApiResolver implements ApiHolder {
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private readonly apis = new Map<AnyApiRef, unknown>();
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/**
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* Validate factories by making sure that each of the apis can be created
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* without hitting any circular dependencies.
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*/
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static validateFactories(
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factories: ApiFactoryHolder,
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apis: Iterable<AnyApiRef>,
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) {
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for (const api of apis) {
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const heap = [api];
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const allDeps = new Set<AnyApiRef>();
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while (heap.length) {
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const apiRef = heap.shift()!;
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const factory = factories.get(apiRef);
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if (!factory) {
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continue;
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}
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for (const dep of Object.values(factory.deps)) {
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if (dep === api) {
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throw new Error(`Circular dependency of api factory for ${api}`);
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}
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if (!allDeps.has(dep)) {
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allDeps.add(dep);
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heap.push(dep);
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}
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}
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}
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}
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}
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constructor(private readonly factories: ApiFactoryHolder) {}
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get<T>(ref: ApiRef<T>): T | undefined {
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return this.load(ref);
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}
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private load<T>(ref: ApiRef<T>, loading: AnyApiRef[] = []): T | undefined {
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const impl = this.apis.get(ref);
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if (impl) {
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return impl as T;
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}
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const factory = this.factories.get(ref);
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if (!factory) {
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return undefined;
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}
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if (loading.includes(factory.implements)) {
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throw new Error(
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`Circular dependency of api factory for ${factory.implements}`,
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);
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}
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const deps = this.loadDeps(ref, factory.deps, [
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...loading,
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factory.implements,
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]);
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const api = factory.factory(deps);
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this.apis.set(ref, api);
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return api as T;
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}
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private loadDeps<T>(
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dependent: ApiRef<unknown>,
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apis: TypesToApiRefs<T>,
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loading: AnyApiRef[],
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): T {
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const impls = {} as T;
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for (const key in apis) {
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if (apis.hasOwnProperty(key)) {
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const ref = apis[key];
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const api = this.load(ref, loading);
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if (!api) {
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throw new Error(
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`No API factory available for dependency ${ref} of dependent ${dependent}`,
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);
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}
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impls[key] = api;
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}
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}
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return impls;
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}
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}
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