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- import { isFunction } from './util/isFunction';
- import { Observer, ObservableNotification } from './types';
- import { isSubscription, Subscription } from './Subscription';
- import { config } from './config';
- import { reportUnhandledError } from './util/reportUnhandledError';
- import { noop } from './util/noop';
- import { nextNotification, errorNotification, COMPLETE_NOTIFICATION } from './NotificationFactories';
- import { timeoutProvider } from './scheduler/timeoutProvider';
- import { captureError } from './util/errorContext';
- /**
- * Implements the {@link Observer} interface and extends the
- * {@link Subscription} class. While the {@link Observer} is the public API for
- * consuming the values of an {@link Observable}, all Observers get converted to
- * a Subscriber, in order to provide Subscription-like capabilities such as
- * `unsubscribe`. Subscriber is a common type in RxJS, and crucial for
- * implementing operators, but it is rarely used as a public API.
- */
- export class Subscriber<T> extends Subscription implements Observer<T> {
- /**
- * A static factory for a Subscriber, given a (potentially partial) definition
- * of an Observer.
- * @param next The `next` callback of an Observer.
- * @param error The `error` callback of an
- * Observer.
- * @param complete The `complete` callback of an
- * Observer.
- * @return A Subscriber wrapping the (partially defined)
- * Observer represented by the given arguments.
- * @deprecated Do not use. Will be removed in v8. There is no replacement for this
- * method, and there is no reason to be creating instances of `Subscriber` directly.
- * If you have a specific use case, please file an issue.
- */
- static create<T>(next?: (x?: T) => void, error?: (e?: any) => void, complete?: () => void): Subscriber<T> {
- return new SafeSubscriber(next, error, complete);
- }
- /** @deprecated Internal implementation detail, do not use directly. Will be made internal in v8. */
- protected isStopped: boolean = false;
- /** @deprecated Internal implementation detail, do not use directly. Will be made internal in v8. */
- protected destination: Subscriber<any> | Observer<any>; // this `any` is the escape hatch to erase extra type param (e.g. R)
- /**
- * @deprecated Internal implementation detail, do not use directly. Will be made internal in v8.
- * There is no reason to directly create an instance of Subscriber. This type is exported for typings reasons.
- */
- constructor(destination?: Subscriber<any> | Observer<any>) {
- super();
- if (destination) {
- this.destination = destination;
- // Automatically chain subscriptions together here.
- // if destination is a Subscription, then it is a Subscriber.
- if (isSubscription(destination)) {
- destination.add(this);
- }
- } else {
- this.destination = EMPTY_OBSERVER;
- }
- }
- /**
- * The {@link Observer} callback to receive notifications of type `next` from
- * the Observable, with a value. The Observable may call this method 0 or more
- * times.
- * @param value The `next` value.
- */
- next(value: T): void {
- if (this.isStopped) {
- handleStoppedNotification(nextNotification(value), this);
- } else {
- this._next(value!);
- }
- }
- /**
- * The {@link Observer} callback to receive notifications of type `error` from
- * the Observable, with an attached `Error`. Notifies the Observer that
- * the Observable has experienced an error condition.
- * @param err The `error` exception.
- */
- error(err?: any): void {
- if (this.isStopped) {
- handleStoppedNotification(errorNotification(err), this);
- } else {
- this.isStopped = true;
- this._error(err);
- }
- }
- /**
- * The {@link Observer} callback to receive a valueless notification of type
- * `complete` from the Observable. Notifies the Observer that the Observable
- * has finished sending push-based notifications.
- */
- complete(): void {
- if (this.isStopped) {
- handleStoppedNotification(COMPLETE_NOTIFICATION, this);
- } else {
- this.isStopped = true;
- this._complete();
- }
- }
- unsubscribe(): void {
- if (!this.closed) {
- this.isStopped = true;
- super.unsubscribe();
- this.destination = null!;
- }
- }
- protected _next(value: T): void {
- this.destination.next(value);
- }
- protected _error(err: any): void {
- try {
- this.destination.error(err);
- } finally {
- this.unsubscribe();
- }
- }
- protected _complete(): void {
- try {
- this.destination.complete();
- } finally {
- this.unsubscribe();
- }
- }
- }
- /**
- * This bind is captured here because we want to be able to have
- * compatibility with monoid libraries that tend to use a method named
- * `bind`. In particular, a library called Monio requires this.
- */
- const _bind = Function.prototype.bind;
- function bind<Fn extends (...args: any[]) => any>(fn: Fn, thisArg: any): Fn {
- return _bind.call(fn, thisArg);
- }
- /**
- * Internal optimization only, DO NOT EXPOSE.
- * @internal
- */
- class ConsumerObserver<T> implements Observer<T> {
- constructor(private partialObserver: Partial<Observer<T>>) {}
- next(value: T): void {
- const { partialObserver } = this;
- if (partialObserver.next) {
- try {
- partialObserver.next(value);
- } catch (error) {
- handleUnhandledError(error);
- }
- }
- }
- error(err: any): void {
- const { partialObserver } = this;
- if (partialObserver.error) {
- try {
- partialObserver.error(err);
- } catch (error) {
- handleUnhandledError(error);
- }
- } else {
- handleUnhandledError(err);
- }
- }
- complete(): void {
- const { partialObserver } = this;
- if (partialObserver.complete) {
- try {
- partialObserver.complete();
- } catch (error) {
- handleUnhandledError(error);
- }
- }
- }
- }
- export class SafeSubscriber<T> extends Subscriber<T> {
- constructor(
- observerOrNext?: Partial<Observer<T>> | ((value: T) => void) | null,
- error?: ((e?: any) => void) | null,
- complete?: (() => void) | null
- ) {
- super();
- let partialObserver: Partial<Observer<T>>;
- if (isFunction(observerOrNext) || !observerOrNext) {
- // The first argument is a function, not an observer. The next
- // two arguments *could* be observers, or they could be empty.
- partialObserver = {
- next: (observerOrNext ?? undefined) as ((value: T) => void) | undefined,
- error: error ?? undefined,
- complete: complete ?? undefined,
- };
- } else {
- // The first argument is a partial observer.
- let context: any;
- if (this && config.useDeprecatedNextContext) {
- // This is a deprecated path that made `this.unsubscribe()` available in
- // next handler functions passed to subscribe. This only exists behind a flag
- // now, as it is *very* slow.
- context = Object.create(observerOrNext);
- context.unsubscribe = () => this.unsubscribe();
- partialObserver = {
- next: observerOrNext.next && bind(observerOrNext.next, context),
- error: observerOrNext.error && bind(observerOrNext.error, context),
- complete: observerOrNext.complete && bind(observerOrNext.complete, context),
- };
- } else {
- // The "normal" path. Just use the partial observer directly.
- partialObserver = observerOrNext;
- }
- }
- // Wrap the partial observer to ensure it's a full observer, and
- // make sure proper error handling is accounted for.
- this.destination = new ConsumerObserver(partialObserver);
- }
- }
- function handleUnhandledError(error: any) {
- if (config.useDeprecatedSynchronousErrorHandling) {
- captureError(error);
- } else {
- // Ideal path, we report this as an unhandled error,
- // which is thrown on a new call stack.
- reportUnhandledError(error);
- }
- }
- /**
- * An error handler used when no error handler was supplied
- * to the SafeSubscriber -- meaning no error handler was supplied
- * do the `subscribe` call on our observable.
- * @param err The error to handle
- */
- function defaultErrorHandler(err: any) {
- throw err;
- }
- /**
- * A handler for notifications that cannot be sent to a stopped subscriber.
- * @param notification The notification being sent.
- * @param subscriber The stopped subscriber.
- */
- function handleStoppedNotification(notification: ObservableNotification<any>, subscriber: Subscriber<any>) {
- const { onStoppedNotification } = config;
- onStoppedNotification && timeoutProvider.setTimeout(() => onStoppedNotification(notification, subscriber));
- }
- /**
- * The observer used as a stub for subscriptions where the user did not
- * pass any arguments to `subscribe`. Comes with the default error handling
- * behavior.
- */
- export const EMPTY_OBSERVER: Readonly<Observer<any>> & { closed: true } = {
- closed: true,
- next: noop,
- error: defaultErrorHandler,
- complete: noop,
- };
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