| import { Operator } from '../Operator'; |
| import { Subscriber } from '../Subscriber'; |
| import { Observable } from '../Observable'; |
| import { MonoTypeOperatorFunction, PartialObserver, TeardownLogic } from '../types'; |
| import { noop } from '../util/noop'; |
| import { isFunction } from '../util/isFunction'; |
| |
| /* tslint:disable:max-line-length */ |
| /** @deprecated Use an observer instead of a complete callback */ |
| export function tap<T>(next: null | undefined, error: null | undefined, complete: () => void): MonoTypeOperatorFunction<T>; |
| /** @deprecated Use an observer instead of an error callback */ |
| export function tap<T>(next: null | undefined, error: (error: any) => void, complete?: () => void): MonoTypeOperatorFunction<T>; |
| /** @deprecated Use an observer instead of a complete callback */ |
| export function tap<T>(next: (value: T) => void, error: null | undefined, complete: () => void): MonoTypeOperatorFunction<T>; |
| export function tap<T>(next?: (x: T) => void, error?: (e: any) => void, complete?: () => void): MonoTypeOperatorFunction<T>; |
| export function tap<T>(observer: PartialObserver<T>): MonoTypeOperatorFunction<T>; |
| /* tslint:enable:max-line-length */ |
| |
| /** |
| * Perform a side effect for every emission on the source Observable, but return |
| * an Observable that is identical to the source. |
| * |
| * <span class="informal">Intercepts each emission on the source and runs a |
| * function, but returns an output which is identical to the source as long as errors don't occur.</span> |
| * |
| * ![](do.png) |
| * |
| * Returns a mirrored Observable of the source Observable, but modified so that |
| * the provided Observer is called to perform a side effect for every value, |
| * error, and completion emitted by the source. Any errors that are thrown in |
| * the aforementioned Observer or handlers are safely sent down the error path |
| * of the output Observable. |
| * |
| * This operator is useful for debugging your Observables for the correct values |
| * or performing other side effects. |
| * |
| * Note: this is different to a `subscribe` on the Observable. If the Observable |
| * returned by `tap` is not subscribed, the side effects specified by the |
| * Observer will never happen. `tap` therefore simply spies on existing |
| * execution, it does not trigger an execution to happen like `subscribe` does. |
| * |
| * ## Example |
| * Map every click to the clientX position of that click, while also logging the click event |
| * ```ts |
| * import { fromEvent } from 'rxjs'; |
| * import { tap, map } from 'rxjs/operators'; |
| * |
| * const clicks = fromEvent(document, 'click'); |
| * const positions = clicks.pipe( |
| * tap(ev => console.log(ev)), |
| * map(ev => ev.clientX), |
| * ); |
| * positions.subscribe(x => console.log(x)); |
| * ``` |
| * |
| * @see {@link map} |
| * @see {@link Observable#subscribe} |
| * |
| * @param {Observer|function} [nextOrObserver] A normal Observer object or a |
| * callback for `next`. |
| * @param {function} [error] Callback for errors in the source. |
| * @param {function} [complete] Callback for the completion of the source. |
| * @return {Observable} An Observable identical to the source, but runs the |
| * specified Observer or callback(s) for each item. |
| * @name tap |
| */ |
| export function tap<T>(nextOrObserver?: PartialObserver<T> | ((x: T) => void), |
| error?: (e: any) => void, |
| complete?: () => void): MonoTypeOperatorFunction<T> { |
| return function tapOperatorFunction(source: Observable<T>): Observable<T> { |
| return source.lift(new DoOperator(nextOrObserver, error, complete)); |
| }; |
| } |
| |
| class DoOperator<T> implements Operator<T, T> { |
| constructor(private nextOrObserver?: PartialObserver<T> | ((x: T) => void), |
| private error?: (e: any) => void, |
| private complete?: () => void) { |
| } |
| call(subscriber: Subscriber<T>, source: any): TeardownLogic { |
| return source.subscribe(new TapSubscriber(subscriber, this.nextOrObserver, this.error, this.complete)); |
| } |
| } |
| |
| /** |
| * We need this JSDoc comment for affecting ESDoc. |
| * @ignore |
| * @extends {Ignored} |
| */ |
| |
| class TapSubscriber<T> extends Subscriber<T> { |
| private _context: any; |
| |
| private _tapNext: ((value: T) => void) = noop; |
| |
| private _tapError: ((err: any) => void) = noop; |
| |
| private _tapComplete: (() => void) = noop; |
| |
| constructor(destination: Subscriber<T>, |
| observerOrNext?: PartialObserver<T> | ((value: T) => void), |
| error?: (e?: any) => void, |
| complete?: () => void) { |
| super(destination); |
| this._tapError = error || noop; |
| this._tapComplete = complete || noop; |
| if (isFunction(observerOrNext)) { |
| this._context = this; |
| this._tapNext = observerOrNext; |
| } else if (observerOrNext) { |
| this._context = observerOrNext; |
| this._tapNext = observerOrNext.next || noop; |
| this._tapError = observerOrNext.error || noop; |
| this._tapComplete = observerOrNext.complete || noop; |
| } |
| } |
| |
| _next(value: T) { |
| try { |
| this._tapNext.call(this._context, value); |
| } catch (err) { |
| this.destination.error(err); |
| return; |
| } |
| this.destination.next(value); |
| } |
| |
| _error(err: any) { |
| try { |
| this._tapError.call(this._context, err); |
| } catch (err) { |
| this.destination.error(err); |
| return; |
| } |
| this.destination.error(err); |
| } |
| |
| _complete() { |
| try { |
| this._tapComplete.call(this._context, ); |
| } catch (err) { |
| this.destination.error(err); |
| return; |
| } |
| return this.destination.complete(); |
| } |
| } |