angular-docs-cn/packages/compiler/src/ng_module_resolver.ts

/**
 * @license
 * Copyright Google Inc. All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */

import {CompileReflector} from './compile_reflector';
import {NgModule, Type, createNgModule} from './core';
import {findLast} from './directive_resolver';
import {stringify} from './util';


/**
 * Resolves types to {@link NgModule}.
 */
export class NgModuleResolver {
  constructor(private _reflector: CompileReflector) {}

  isNgModule(type: any) { return this._reflector.annotations(type).some(createNgModule.isTypeOf); }

  resolve(type: Type, throwIfNotFound = true): NgModule|null {
    const ngModuleMeta: NgModule =
        findLast(this._reflector.annotations(type), createNgModule.isTypeOf);

    if (ngModuleMeta) {
      return ngModuleMeta;
    } else {
      if (throwIfNotFound) {
        throw new Error(`No NgModule metadata found for '${stringify(type)}'.`);
      }
      return null;
    }
  }
}