import { OperatorFunction, ObservableInputTuple } from '../types';
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import { raceInit } from '../observable/race';
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import { operate } from '../util/lift';
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import { identity } from '../util/identity';
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/**
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* Creates an Observable that mirrors the first source Observable to emit a next,
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* error or complete notification from the combination of the Observable to which
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* the operator is applied and supplied Observables.
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*
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* ## Example
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*
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* ```ts
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* import { interval, map, raceWith } from 'rxjs';
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*
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* const obs1 = interval(7000).pipe(map(() => 'slow one'));
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* const obs2 = interval(3000).pipe(map(() => 'fast one'));
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* const obs3 = interval(5000).pipe(map(() => 'medium one'));
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*
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* obs1
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* .pipe(raceWith(obs2, obs3))
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* .subscribe(winner => console.log(winner));
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*
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* // Outputs
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* // a series of 'fast one'
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* ```
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*
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* @param otherSources Sources used to race for which Observable emits first.
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* @return A function that returns an Observable that mirrors the output of the
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* first Observable to emit an item.
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*/
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export function raceWith<T, A extends readonly unknown[]>(
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...otherSources: [...ObservableInputTuple<A>]
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): OperatorFunction<T, T | A[number]> {
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return !otherSources.length
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? identity
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: operate((source, subscriber) => {
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raceInit<T | A[number]>([source, ...otherSources])(subscriber);
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});
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}
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