@reactivex/rxjs/dist/cjs/operator/mergeMap.d.ts

Reactive Extensions for modern JavaScript

import { Observable, ObservableInput } from '../Observable';
import { Operator } from '../Operator';
import { Subscriber } from '../Subscriber';
import { Subscription } from '../Subscription';
import { OuterSubscriber } from '../OuterSubscriber';
import { InnerSubscriber } from '../InnerSubscriber';
/**
 * Projects each source value to an Observable which is merged in the output
 * Observable.
 *
 * <span class="informal">Maps each value to an Observable, then flattens all of
 * these inner Observables using {@link mergeAll}.</span>
 *
 * <img src="./img/mergeMap.png" width="100%">
 *
 * 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 Observable, and then merging those resulting Observables and
 * emitting the results of this merger.
 *
 * @example <caption>Map and flatten each letter to an Observable ticking every 1 second</caption>
 * var letters = Rx.Observable.of('a', 'b', 'c');
 * var result = letters.mergeMap(x =>
 *   Rx.Observable.interval(1000).map(i => x+i)
 * );
 * result.subscribe(x => console.log(x));
 *
 * @see {@link concatMap}
 * @see {@link exhaustMap}
 * @see {@link merge}
 * @see {@link mergeAll}
 * @see {@link mergeMapTo}
 * @see {@link mergeScan}
 * @see {@link switchMap}
 *
 * @param {function(value: T, ?index: number): Observable} project A function
 * that, when applied to an item emitted by the source Observable, returns an
 * Observable.
 * @param {function(outerValue: T, innerValue: I, outerIndex: number, innerIndex: number): any} [resultSelector]
 * A function to produce the value on the output Observable based on the values
 * and the indices of the source (outer) emission and the inner Observable
 * emission. The arguments passed to this function are:
 * - `outerValue`: the value that came from the source
 * - `innerValue`: the value that came from the projected Observable
 * - `outerIndex`: the "index" of the value that came from the source
 * - `innerIndex`: the "index" of the value from the projected Observable
 * @param {number} [concurrent=Number.POSITIVE_INFINITY] Maximum number of input
 * Observables being subscribed to concurrently.
 * @return {Observable} An Observable that emits the result of applying the
 * projection function (and the optional `resultSelector`) to each item emitted
 * by the source Observable and merging the results of the Observables obtained
 * from this transformation.
 * @method mergeMap
 * @owner Observable
 */
export declare function mergeMap<T, I, R>(project: (value: T, index: number) => ObservableInput<I>, resultSelector?: ((outerValue: T, innerValue: I, outerIndex: number, innerIndex: number) => R) | number, concurrent?: number): Observable<R>;
export interface MergeMapSignature<T> {
    <R>(project: (value: T, index: number) => ObservableInput<R>, concurrent?: number): Observable<R>;
    <I, R>(project: (value: T, index: number) => ObservableInput<I>, resultSelector: (outerValue: T, innerValue: I, outerIndex: number, innerIndex: number) => R, concurrent?: number): Observable<R>;
}
export declare class MergeMapOperator<T, I, R> implements Operator<T, I> {
    private project;
    private resultSelector;
    private concurrent;
    constructor(project: (value: T, index: number) => ObservableInput<I>, resultSelector?: (outerValue: T, innerValue: I, outerIndex: number, innerIndex: number) => R, concurrent?: number);
    call(observer: Subscriber<I>, source: any): any;
}
/**
 * We need this JSDoc comment for affecting ESDoc.
 * @ignore
 * @extends {Ignored}
 */
export declare class MergeMapSubscriber<T, I, R> extends OuterSubscriber<T, I> {
    private project;
    private resultSelector;
    private concurrent;
    private hasCompleted;
    private buffer;
    private active;
    protected index: number;
    constructor(destination: Subscriber<I>, project: (value: T, index: number) => ObservableInput<I>, resultSelector?: (outerValue: T, innerValue: I, outerIndex: number, innerIndex: number) => R, concurrent?: number);
    protected _next(value: any): void;
    protected _tryNext(value: any): void;
    private _innerSub(ish, value, index);
    protected _complete(): void;
    notifyNext(outerValue: T, innerValue: I, outerIndex: number, innerIndex: number, innerSub: InnerSubscriber<T, I>): void;
    _notifyResultSelector(outerValue: T, innerValue: I, outerIndex: number, innerIndex: number): void;
    notifyComplete(innerSub: Subscription): void;
}