@reactivex/rxjs/dist/cjs/src/observable/dom/WebSocketSubject.ts

Reactive Extensions for modern JavaScript

import {Subject, AnonymousSubject} from '../../Subject';
import {Subscriber} from '../../Subscriber';
import {Observable} from '../../Observable';
import {Operator} from '../../Operator';
import {Subscription} from '../../Subscription';
import {root} from '../../util/root';
import {ReplaySubject} from '../../ReplaySubject';
import {Observer, NextObserver} from '../../Observer';
import {tryCatch} from '../../util/tryCatch';
import {errorObject} from '../../util/errorObject';
import {assign} from '../../util/assign';

export interface WebSocketSubjectConfig {
  url: string;
  protocol?: string | Array<string>;
  resultSelector?: <T>(e: MessageEvent) => T;
  openObserver?: NextObserver<Event>;
  closeObserver?: NextObserver<CloseEvent>;
  closingObserver?: NextObserver<void>;
  WebSocketCtor?: { new(url: string, protocol?: string|Array<string>): WebSocket };
}

/**
 * We need this JSDoc comment for affecting ESDoc.
 * @extends {Ignored}
 * @hide true
 */
export class WebSocketSubject<T> extends AnonymousSubject<T> {
  url: string;
  protocol: string|Array<string>;
  socket: WebSocket;
  openObserver: NextObserver<Event>;
  closeObserver: NextObserver<CloseEvent>;
  closingObserver: NextObserver<void>;
  WebSocketCtor: { new(url: string, protocol?: string|Array<string>): WebSocket };
  private _output: Subject<T> = new Subject<T>();

  resultSelector(e: MessageEvent) {
    return JSON.parse(e.data);
  }

  /**
   * @param urlConfigOrSource
   * @return {WebSocketSubject}
   * @static true
   * @name webSocket
   * @owner Observable
   */
  static create<T>(urlConfigOrSource: string | WebSocketSubjectConfig): WebSocketSubject<T> {
    return new WebSocketSubject<T>(urlConfigOrSource);
  }

  constructor(urlConfigOrSource: string | WebSocketSubjectConfig | Observable<T>, destination?: Observer<T>) {
    super();
    this.WebSocketCtor = root.WebSocket;

    if (typeof urlConfigOrSource === 'string') {
      this.url = urlConfigOrSource;
    } else {
      // WARNING: config object could override important members here.
      assign(this, urlConfigOrSource);
    }

    if (!this.WebSocketCtor) {
      throw new Error('no WebSocket constructor can be found');
    }

    this.destination = new ReplaySubject();
  }

  lift<R>(operator: Operator<T, R>) {
    const sock: WebSocketSubject<T> = new WebSocketSubject(this, this.destination);
    sock.operator = <any>operator;
    return sock;
  }

  // TODO: factor this out to be a proper Operator/Subscriber implementation and eliminate closures
  multiplex(subMsg: () => any, unsubMsg: () => any, messageFilter: (value: T) => boolean) {
    const self = this;
    return new Observable((observer: Observer<any>) => {
      const result = tryCatch(subMsg)();
      if (result === errorObject) {
        observer.error(errorObject.e);
      } else {
        self.next(result);
      }

      let subscription = self.subscribe(x => {
        const result = tryCatch(messageFilter)(x);
        if (result === errorObject) {
          observer.error(errorObject.e);
        } else if (result) {
          observer.next(x);
        }
      },
        err => observer.error(err),
        () => observer.complete());

      return () => {
        const result = tryCatch(unsubMsg)();
        if (result === errorObject) {
          observer.error(errorObject.e);
        } else {
          self.next(result);
        }
        subscription.unsubscribe();
      };
    });
  }

  private _connectSocket() {
    const socket = this.protocol ? new WebSocket(this.url, this.protocol) : new WebSocket(this.url);
    this.socket = socket;
    const subscription = new Subscription(() => {
      this.socket = null;
      if (socket && socket.readyState === 1) {
        socket.close();
      }
    });

    const observer = this._output;

    socket.onopen = (e: Event) => {
      const openObserver = this.openObserver;
      if (openObserver) {
        openObserver.next(e);
      }

      const queue = this.destination;

      this.destination = Subscriber.create(
        (x) => socket.readyState === 1 && socket.send(x),
        (e) => {
          const closingObserver = this.closingObserver;
          if (closingObserver) {
            closingObserver.next(undefined);
          }
          if (e && e.code) {
            socket.close(e.code, e.reason);
          } else {
            observer.error(new TypeError('WebSocketSubject.error must be called with an object with an error code, ' +
              'and an optional reason: { code: number, reason: string }'));
          }
          this.destination = new ReplaySubject();
          this.socket = null;
        },
        ( ) => {
          const closingObserver = this.closingObserver;
          if (closingObserver) {
            closingObserver.next(undefined);
          }
          socket.close();
          this.destination = new ReplaySubject();
          this.socket = null;
        }
      );

      if (queue && queue instanceof ReplaySubject) {
        subscription.add((<ReplaySubject<T>>queue).subscribe(this.destination));
      }
    };

    socket.onerror = (e: Event) => observer.error(e);

    socket.onclose = (e: CloseEvent) => {
      const closeObserver = this.closeObserver;
      if (closeObserver) {
        closeObserver.next(e);
      }
      if (e.wasClean) {
        observer.complete();
      } else {
        observer.error(e);
      }
    };

    socket.onmessage = (e: MessageEvent) => {
      const result = tryCatch(this.resultSelector)(e);
      if (result === errorObject) {
        observer.error(errorObject.e);
      } else {
        observer.next(result);
      }
    };
  }

  protected _subscribe(subscriber: Subscriber<T>): Subscription {
    if (!this.socket) {
      this._connectSocket();
    }
    let subscription = new Subscription();
    subscription.add(this._output.subscribe(subscriber));
    subscription.add(() => {
      const { socket } = this;
      if (socket && socket.readyState === 1) {
        socket.close();
        this.socket = null;
      }
    });
    return subscription;
  }

  unsubscribe() {
    const { socket } = this;
    if (socket && socket.readyState === 1) {
      socket.close();
      this.socket = null;
    }
    super.unsubscribe();
    this.destination = new ReplaySubject();
  }
}