playwright/src/rpc/client/channelOwner.ts

/**
 * Copyright (c) Microsoft Corporation.
 *
 * 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 { EventEmitter } from 'events';
import { Channel } from '../channels';
import { Connection } from './connection';
import { assert } from '../../helper';

export abstract class ChannelOwner<T extends Channel = Channel, Initializer = {}> extends EventEmitter {
  private _connection: Connection;
  private _isScope: boolean;
  // Parent is always "isScope".
  private _parent: ChannelOwner | undefined;
  // Only "isScope" channel owners have registered objects inside.
  private _objects = new Map<string, ChannelOwner>();

  readonly _guid: string;
  readonly _channel: T;
  readonly _initializer: Initializer;

  constructor(parent: ChannelOwner | Connection, guid: string, initializer: Initializer, isScope?: boolean) {
    super();

    this._connection = parent instanceof Connection ? parent : parent._connection;
    this._guid = guid;
    this._isScope = !!isScope;
    this._parent = parent instanceof Connection ? undefined : parent;

    this._connection._objects.set(guid, this);
    if (this._parent)
      this._parent._objects.set(guid, this);

    const base = new EventEmitter();
    this._channel = new Proxy(base, {
      get: (obj: any, prop) => {
        if (String(prop).startsWith('_'))
          return obj[prop];
        if (prop === 'then')
          return obj.then;
        if (prop === 'emit')
          return obj.emit;
        if (prop === 'on')
          return obj.on;
        if (prop === 'once')
          return obj.once;
        if (prop === 'addEventListener')
          return obj.addListener;
        if (prop === 'removeEventListener')
          return obj.removeListener;
        return (params: any) => this._connection.sendMessageToServer({ guid, method: String(prop), params });
      },
    });
    (this._channel as any)._object = this;
    this._initializer = initializer;
  }

  _dispose() {
    assert(this._isScope);

    // Clean up from parent and connection.
    if (this._parent)
      this._parent._objects.delete(this._guid);
    this._connection._objects.delete(this._guid);

    // Dispose all children.
    for (const [guid, object] of [...this._objects]) {
      if (object._isScope)
        object._dispose();
      else
        this._connection._objects.delete(guid);
    }
    this._objects.clear();
  }

  _debugScopeState(): any {
    return {
      _guid: this._guid,
      objects: this._isScope ? Array.from(this._objects.values()).map(o => o._debugScopeState()) : undefined,
    };
  }
}