From e4fa1e69e7ebfb627c7198fd1a9881e9327ec4d4 Mon Sep 17 00:00:00 2001 From: Pinapelz Date: Sat, 28 Jun 2025 17:26:46 -0700 Subject: initial commit: scaffolding --- .../rxjs/src/internal/operators/switchMap.ts | 132 +++++++++++++++++++++ 1 file changed, 132 insertions(+) create mode 100644 node_modules/rxjs/src/internal/operators/switchMap.ts (limited to 'node_modules/rxjs/src/internal/operators/switchMap.ts') diff --git a/node_modules/rxjs/src/internal/operators/switchMap.ts b/node_modules/rxjs/src/internal/operators/switchMap.ts new file mode 100644 index 0000000..0ded7ba --- /dev/null +++ b/node_modules/rxjs/src/internal/operators/switchMap.ts @@ -0,0 +1,132 @@ +import { Subscriber } from '../Subscriber'; +import { ObservableInput, OperatorFunction, ObservedValueOf } from '../types'; +import { innerFrom } from '../observable/innerFrom'; +import { operate } from '../util/lift'; +import { createOperatorSubscriber } from './OperatorSubscriber'; + +/* tslint:disable:max-line-length */ +export function switchMap>( + project: (value: T, index: number) => O +): OperatorFunction>; +/** @deprecated The `resultSelector` parameter will be removed in v8. Use an inner `map` instead. Details: https://rxjs.dev/deprecations/resultSelector */ +export function switchMap>( + project: (value: T, index: number) => O, + resultSelector: undefined +): OperatorFunction>; +/** @deprecated The `resultSelector` parameter will be removed in v8. Use an inner `map` instead. Details: https://rxjs.dev/deprecations/resultSelector */ +export function switchMap>( + project: (value: T, index: number) => O, + resultSelector: (outerValue: T, innerValue: ObservedValueOf, outerIndex: number, innerIndex: number) => R +): OperatorFunction; +/* tslint:enable:max-line-length */ + +/** + * Projects each source value to an Observable which is merged in the output + * Observable, emitting values only from the most recently projected Observable. + * + * Maps each value to an Observable, then flattens all of + * these inner Observables using {@link switchAll}. + * + * ![](switchMap.png) + * + * Returns an Observable that emits items based on applying a function that you + * supply to each item emitted by the source Observable, where that function + * returns an (so-called "inner") Observable. Each time it observes one of these + * inner Observables, the output Observable begins emitting the items emitted by + * that inner Observable. When a new inner Observable is emitted, `switchMap` + * stops emitting items from the earlier-emitted inner Observable and begins + * emitting items from the new one. It continues to behave like this for + * subsequent inner Observables. + * + * ## Example + * + * Generate new Observable according to source Observable values + * + * ```ts + * import { of, switchMap } from 'rxjs'; + * + * const switched = of(1, 2, 3).pipe(switchMap(x => of(x, x ** 2, x ** 3))); + * switched.subscribe(x => console.log(x)); + * // outputs + * // 1 + * // 1 + * // 1 + * // 2 + * // 4 + * // 8 + * // 3 + * // 9 + * // 27 + * ``` + * + * Restart an interval Observable on every click event + * + * ```ts + * import { fromEvent, switchMap, interval } from 'rxjs'; + * + * const clicks = fromEvent(document, 'click'); + * const result = clicks.pipe(switchMap(() => interval(1000))); + * result.subscribe(x => console.log(x)); + * ``` + * + * @see {@link concatMap} + * @see {@link exhaustMap} + * @see {@link mergeMap} + * @see {@link switchAll} + * @see {@link switchMapTo} + * + * @param project A function that, when applied to an item emitted by the source + * Observable, returns an Observable. + * @return A function that returns an Observable that emits the result of + * applying the projection function (and the optional deprecated + * `resultSelector`) to each item emitted by the source Observable and taking + * only the values from the most recently projected inner Observable. + */ +export function switchMap>( + project: (value: T, index: number) => O, + resultSelector?: (outerValue: T, innerValue: ObservedValueOf, outerIndex: number, innerIndex: number) => R +): OperatorFunction | R> { + return operate((source, subscriber) => { + let innerSubscriber: Subscriber> | null = null; + let index = 0; + // Whether or not the source subscription has completed + let isComplete = false; + + // We only complete the result if the source is complete AND we don't have an active inner subscription. + // This is called both when the source completes and when the inners complete. + const checkComplete = () => isComplete && !innerSubscriber && subscriber.complete(); + + source.subscribe( + createOperatorSubscriber( + subscriber, + (value) => { + // Cancel the previous inner subscription if there was one + innerSubscriber?.unsubscribe(); + let innerIndex = 0; + const outerIndex = index++; + // Start the next inner subscription + innerFrom(project(value, outerIndex)).subscribe( + (innerSubscriber = createOperatorSubscriber( + subscriber, + // When we get a new inner value, next it through. Note that this is + // handling the deprecate result selector here. This is because with this architecture + // it ends up being smaller than using the map operator. + (innerValue) => subscriber.next(resultSelector ? resultSelector(value, innerValue, outerIndex, innerIndex++) : innerValue), + () => { + // The inner has completed. Null out the inner subscriber to + // free up memory and to signal that we have no inner subscription + // currently. + innerSubscriber = null!; + checkComplete(); + } + )) + ); + }, + () => { + isComplete = true; + checkComplete(); + } + ) + ); + }); +} -- cgit v1.2.3