30 lines
995 B
TypeScript
30 lines
995 B
TypeScript
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/**
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* @license
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* Copyright Google Inc. All Rights Reserved.
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*
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* Use of this source code is governed by an MIT-style license that can be
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* found in the LICENSE file at https://angular.io/license
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*/
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import {MonoTypeOperatorFunction, ObservableInput, from} from 'rxjs';
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import {map, switchMap} from 'rxjs/operators';
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/**
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* Perform a side effect through a switchMap for every emission on the source Observable,
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* but return an Observable that is identical to the source. It's essentially the same as
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* the `tap` operator, but if the side effectful `next` function returns an ObservableInput,
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* it will wait before continuing with the original value.
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*/
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export function switchTap<T>(next: (x: T) => void|ObservableInput<any>):
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MonoTypeOperatorFunction<T> {
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return function(source) {
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return source.pipe(switchMap(v => {
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const nextResult = next(v);
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if (nextResult) {
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return from(nextResult).pipe(map(() => v));
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}
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return from([v]);
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}));
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};
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}
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