@reactivex/rxjs/src/operator/concat.ts

Reactive Extensions for modern JavaScript

import {Observable, ObservableInput} from '../Observable';
import {Scheduler} from '../Scheduler';
import {isScheduler} from '../util/isScheduler';
import {ArrayObservable} from '../observable/ArrayObservable';
import {MergeAllOperator} from './mergeAll';

/**
 * Creates an output Observable which sequentially emits all values from every
 * given input Observable after the current Observable.
 *
 * <span class="informal">Concatenates multiple Observables together by
 * sequentially emitting their values, one Observable after the other.</span>
 *
 * <img src="./img/concat.png" width="100%">
 *
 * Joins this Observable with multiple other Observables by subscribing to them
 * one at a time, starting with the source, and merging their results into the
 * output Observable. Will wait for each Observable to complete before moving
 * on to the next.
 *
 * @example <caption>Concatenate a timer counting from 0 to 3 with a synchronous sequence from 1 to 10</caption>
 * var timer = Rx.Observable.interval(1000).take(4);
 * var sequence = Rx.Observable.range(1, 10);
 * var result = timer.concat(sequence);
 * result.subscribe(x => console.log(x));
 *
 * @example <caption>Concatenate 3 Observables</caption>
 * var timer1 = Rx.Observable.interval(1000).take(10);
 * var timer2 = Rx.Observable.interval(2000).take(6);
 * var timer3 = Rx.Observable.interval(500).take(10);
 * var result = timer1.concat(timer2, timer3);
 * result.subscribe(x => console.log(x));
 *
 * @see {@link concatAll}
 * @see {@link concatMap}
 * @see {@link concatMapTo}
 *
 * @param {Observable} other An input Observable to concatenate after the source
 * Observable. More than one input Observables may be given as argument.
 * @param {Scheduler} [scheduler=null] An optional Scheduler to schedule each
 * Observable subscription on.
 * @return {Observable} All values of each passed Observable merged into a
 * single Observable, in order, in serial fashion.
 * @method concat
 * @owner Observable
 */
export function concat<T, R>(...observables: Array<ObservableInput<any> | Scheduler>): Observable<R> {
  return concatStatic<T, R>(this, ...observables);
}

/* tslint:disable:max-line-length */
export interface ConcatSignature<T> {
  (scheduler?: Scheduler): Observable<T>;
  <T2>(v2: ObservableInput<T2>, scheduler?: Scheduler): Observable<T | T2>;
  <T2, T3>(v2: ObservableInput<T2>, v3: ObservableInput<T3>, scheduler?: Scheduler): Observable<T | T2 | T3>;
  <T2, T3, T4>(v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, scheduler?: Scheduler): Observable<T | T2 | T3 | T4>;
  <T2, T3, T4, T5>(v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, v5: ObservableInput<T5>, scheduler?: Scheduler): Observable<T | T2 | T3 | T4 | T5>;
  <T2, T3, T4, T5, T6>(v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, v5: ObservableInput<T5>, v6: ObservableInput<T6>, scheduler?: Scheduler): Observable<T | T2 | T3 | T4 | T5 | T6>;
  (...observables: Array<ObservableInput<T> | Scheduler>): Observable<T>;
  <R>(...observables: Array<ObservableInput<any> | Scheduler>): Observable<R>;
}
/* tslint:enable:max-line-length */

/* tslint:disable:max-line-length */
export function concatStatic<T>(v1: ObservableInput<T>, scheduler?: Scheduler): Observable<T>;
export function concatStatic<T, T2>(v1: ObservableInput<T>, v2: ObservableInput<T2>, scheduler?: Scheduler): Observable<T | T2>;
export function concatStatic<T, T2, T3>(v1: ObservableInput<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, scheduler?: Scheduler): Observable<T | T2 | T3>;
export function concatStatic<T, T2, T3, T4>(v1: ObservableInput<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, scheduler?: Scheduler): Observable<T | T2 | T3 | T4>;
export function concatStatic<T, T2, T3, T4, T5>(v1: ObservableInput<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, v5: ObservableInput<T5>, scheduler?: Scheduler): Observable<T | T2 | T3 | T4 | T5>;
export function concatStatic<T, T2, T3, T4, T5, T6>(v1: ObservableInput<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, v5: ObservableInput<T5>, v6: ObservableInput<T6>, scheduler?: Scheduler): Observable<T | T2 | T3 | T4 | T5 | T6>;
export function concatStatic<T>(...observables: (ObservableInput<T> | Scheduler)[]): Observable<T>;
export function concatStatic<T, R>(...observables: (ObservableInput<any> | Scheduler)[]): Observable<R>;
/* tslint:enable:max-line-length */
/**
 * Creates an output Observable which sequentially emits all values from every
 * given input Observable after the current Observable.
 *
 * <span class="informal">Concatenates multiple Observables together by
 * sequentially emitting their values, one Observable after the other.</span>
 *
 * <img src="./img/concat.png" width="100%">
 *
 * Joins multiple Observables together by subscribing to them one at a time and
 * merging their results into the output Observable. Will wait for each
 * Observable to complete before moving on to the next.
 *
 * @example <caption>Concatenate a timer counting from 0 to 3 with a synchronous sequence from 1 to 10</caption>
 * var timer = Rx.Observable.interval(1000).take(4);
 * var sequence = Rx.Observable.range(1, 10);
 * var result = Rx.Observable.concat(timer, sequence);
 * result.subscribe(x => console.log(x));
 *
 * @example <caption>Concatenate 3 Observables</caption>
 * var timer1 = Rx.Observable.interval(1000).take(10);
 * var timer2 = Rx.Observable.interval(2000).take(6);
 * var timer3 = Rx.Observable.interval(500).take(10);
 * var result = Rx.Observable.concat(timer1, timer2, timer3);
 * result.subscribe(x => console.log(x));
 *
 * @see {@link concatAll}
 * @see {@link concatMap}
 * @see {@link concatMapTo}
 *
 * @param {Observable} input1 An input Observable to concatenate with others.
 * @param {Observable} input2 An input Observable to concatenate with others.
 * More than one input Observables may be given as argument.
 * @param {Scheduler} [scheduler=null] An optional Scheduler to schedule each
 * Observable subscription on.
 * @return {Observable} All values of each passed Observable merged into a
 * single Observable, in order, in serial fashion.
 * @static true
 * @name concat
 * @owner Observable
 */
export function concatStatic<T, R>(...observables: Array<ObservableInput<any> | Scheduler>): Observable<R> {
  let scheduler: Scheduler = null;
  let args = <any[]>observables;
  if (isScheduler(args[observables.length - 1])) {
    scheduler = args.pop();
  }

  return new ArrayObservable(observables, scheduler).lift(new MergeAllOperator<R>(1));
}