Function downgradeModule

packages/upgrade/static/src/downgrade_module.ts:373–452

(
  moduleOrBootstrapFn:
    | Type<T>
    | NgModuleFactory<T>
    | ((extraProviders: StaticProvider[]) => Promise<NgModuleRef<T>>),
)

 * @publicApi
 */
export function downgradeModule<T>(
  moduleOrBootstrapFn:
    | Type<T>
    | NgModuleFactory<T>
    | ((extraProviders: StaticProvider[]) => Promise<NgModuleRef<T>>),
): string {
  const lazyModuleName = `${ɵconstants.UPGRADE_MODULE_NAME}.lazy${++moduleUid}`;
  const lazyModuleRefKey = `${ɵconstants.LAZY_MODULE_REF}${lazyModuleName}`;
  const lazyInjectorKey = `${ɵconstants.INJECTOR_KEY}${lazyModuleName}`;

  let bootstrapFn: (extraProviders: StaticProvider[]) => Promise<NgModuleRef<T>>;
  if (ɵutil.isNgModuleType(moduleOrBootstrapFn)) {
    // NgModule class
    bootstrapFn = (extraProviders: StaticProvider[]) =>
      platformBrowser(extraProviders).bootstrapModule(moduleOrBootstrapFn, {
        applicationProviders: [internalProvideZoneChangeDetection({})],
      });
  } else if (!ɵutil.isFunction(moduleOrBootstrapFn)) {
    // NgModule factory
    bootstrapFn = (extraProviders: StaticProvider[]) =>
      platformBrowser(extraProviders).bootstrapModuleFactory(moduleOrBootstrapFn, {
        applicationProviders: [internalProvideZoneChangeDetection({})],
      });
  } else {
    // bootstrap function
    bootstrapFn = moduleOrBootstrapFn;
  }

  let injector: Injector;

  // Create an ng1 module to bootstrap.
  ɵangular1
    .module_(lazyModuleName, [])
    .constant(ɵconstants.UPGRADE_APP_TYPE_KEY, ɵutil.UpgradeAppType.Lite)
    .factory(ɵconstants.INJECTOR_KEY, [lazyInjectorKey, identity])
    .factory(lazyInjectorKey, () => {
      if (!injector) {
        throw new Error(
          'Trying to get the Angular injector before bootstrapping the corresponding ' +
            'Angular module.',
        );
      }
      return injector;
    })
    .factory(ɵconstants.LAZY_MODULE_REF, [lazyModuleRefKey, identity])
    .factory(lazyModuleRefKey, [
      ɵconstants.$INJECTOR,
      ($injector: ɵangular1.IInjectorService) => {
        setTempInjectorRef($injector);
        const result: ɵutil.LazyModuleRef = {
          promise: bootstrapFn(angular1Providers).then((ref) => {
            injector = result.injector = new NgAdapterInjector(ref.injector);
            injector.get(ɵconstants.$INJECTOR);

            // Destroy the AngularJS app once the Angular `PlatformRef` is destroyed.
            // This does not happen in a typical SPA scenario, but it might be useful for
            // other use-cases where disposing of an Angular/AngularJS app is necessary
            // (such as Hot Module Replacement (HMR)).