node-adapter.ts

/**
 * Copyright 2019 Google Inc. All Rights Reserved.
 * 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 { Endpoint } from "./protocol.js";

export interface NodeEndpoint {
  postMessage(message: any, transfer?: any[]): void;
  on(
    type: string,
    listener: EventListenerOrEventListenerObject,
    options?: {}
  ): void;
  off(
    type: string,
    listener: EventListenerOrEventListenerObject,
    options?: {}
  ): void;
  start?: () => void;
}

export default function nodeEndpoint(nep: NodeEndpoint): Endpoint {
  const listeners = new WeakMap();
  return {
    postMessage: nep.postMessage.bind(nep),
    addEventListener: (_, eh) => {
      const l = (data: any) => {
        if ("handleEvent" in eh) {
          eh.handleEvent({ data } as MessageEvent);
        } else {
          eh({ data } as MessageEvent);
        }
      };
      nep.on("message", l);
      listeners.set(eh, l);
    },
    removeEventListener: (_, eh) => {
      const l = listeners.get(eh);
      if (!l) {
        return;
      }
      nep.off("message", l);
      listeners.delete(eh);
    },
    start: nep.start && nep.start.bind(nep)
  };
}