+++ /dev/null
-import { Operator } from '../Operator';
-import { Subscriber } from '../Subscriber';
-import { ArgumentOutOfRangeError } from '../util/ArgumentOutOfRangeError';
-import { empty } from '../observable/empty';
-import { Observable } from '../Observable';
-import { MonoTypeOperatorFunction, TeardownLogic } from '../types';
-
-/**
- * Emits only the first `count` values emitted by the source Observable.
- *
- * <span class="informal">Takes the first `count` values from the source, then
- * completes.</span>
- *
- * ![](take.png)
- *
- * `take` returns an Observable that emits only the first `count` values emitted
- * by the source Observable. If the source emits fewer than `count` values then
- * all of its values are emitted. After that, it completes, regardless if the
- * source completes.
- *
- * ## Example
- * Take the first 5 seconds of an infinite 1-second interval Observable
- * ```ts
- * import { interval } from 'rxjs';
- * import { take } from 'rxjs/operators';
- *
- * const intervalCount = interval(1000);
- * const takeFive = intervalCount.pipe(take(5));
- * takeFive.subscribe(x => console.log(x));
- *
- * // Logs:
- * // 0
- * // 1
- * // 2
- * // 3
- * // 4
- * ```
- *
- * @see {@link takeLast}
- * @see {@link takeUntil}
- * @see {@link takeWhile}
- * @see {@link skip}
- *
- * @throws {ArgumentOutOfRangeError} When using `take(i)`, it delivers an
- * ArgumentOutOrRangeError to the Observer's `error` callback if `i < 0`.
- *
- * @param {number} count The maximum number of `next` values to emit.
- * @return {Observable<T>} An Observable that emits only the first `count`
- * values emitted by the source Observable, or all of the values from the source
- * if the source emits fewer than `count` values.
- * @method take
- * @owner Observable
- */
-export function take<T>(count: number): MonoTypeOperatorFunction<T> {
- return (source: Observable<T>) => {
- if (count === 0) {
- return empty();
- } else {
- return source.lift(new TakeOperator(count));
- }
- };
-}
-
-class TakeOperator<T> implements Operator<T, T> {
- constructor(private total: number) {
- if (this.total < 0) {
- throw new ArgumentOutOfRangeError;
- }
- }
-
- call(subscriber: Subscriber<T>, source: any): TeardownLogic {
- return source.subscribe(new TakeSubscriber(subscriber, this.total));
- }
-}
-
-/**
- * We need this JSDoc comment for affecting ESDoc.
- * @ignore
- * @extends {Ignored}
- */
-class TakeSubscriber<T> extends Subscriber<T> {
- private count: number = 0;
-
- constructor(destination: Subscriber<T>, private total: number) {
- super(destination);
- }
-
- protected _next(value: T): void {
- const total = this.total;
- const count = ++this.count;
- if (count <= total) {
- this.destination.next(value);
- if (count === total) {
- this.destination.complete();
- this.unsubscribe();
- }
- }
- }
-}