import { Observable } from '../Observable';
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import { ObservableInput, OperatorFunction } from '../types';
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import { identity } from '../util/identity';
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import { mapOneOrManyArgs } from '../util/mapOneOrManyArgs';
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import { pipe } from '../util/pipe';
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import { mergeMap } from './mergeMap';
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import { toArray } from './toArray';
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/**
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* Collects all of the inner sources from source observable. Then, once the
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* source completes, joins the values using the given static.
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*
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* This is used for {@link combineLatestAll} and {@link zipAll} which both have the
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* same behavior of collecting all inner observables, then operating on them.
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*
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* @param joinFn The type of static join to apply to the sources collected
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* @param project The projection function to apply to the values, if any
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*/
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export function joinAllInternals<T, R>(joinFn: (sources: ObservableInput<T>[]) => Observable<T>, project?: (...args: any[]) => R) {
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return pipe(
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// Collect all inner sources into an array, and emit them when the
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// source completes.
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toArray() as OperatorFunction<ObservableInput<T>, ObservableInput<T>[]>,
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// Run the join function on the collected array of inner sources.
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mergeMap((sources) => joinFn(sources)),
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// If a projection function was supplied, apply it to each result.
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project ? mapOneOrManyArgs(project) : (identity as any)
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);
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}
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