biofriction-wp-theme/node_modules/rxjs/_esm2015/operators/take.js

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2021-10-26 14:18:09 +02:00
import { Subscriber } from '../Subscriber';
import { ArgumentOutOfRangeError } from '../util/ArgumentOutOfRangeError';
import { EmptyObservable } from '../observable/EmptyObservable';
/**
* 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>
*
* <img src="./img/take.png" width="100%">
*
* `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 <caption>Take the first 5 seconds of an infinite 1-second interval Observable</caption>
* var interval = Rx.Observable.interval(1000);
* var five = interval.take(5);
* five.subscribe(x => console.log(x));
*
* @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(count) {
return (source) => {
if (count === 0) {
return new EmptyObservable();
}
else {
return source.lift(new TakeOperator(count));
}
};
}
class TakeOperator {
constructor(total) {
this.total = total;
if (this.total < 0) {
throw new ArgumentOutOfRangeError;
}
}
call(subscriber, source) {
return source.subscribe(new TakeSubscriber(subscriber, this.total));
}
}
/**
* We need this JSDoc comment for affecting ESDoc.
* @ignore
* @extends {Ignored}
*/
class TakeSubscriber extends Subscriber {
constructor(destination, total) {
super(destination);
this.total = total;
this.count = 0;
}
_next(value) {
const total = this.total;
const count = ++this.count;
if (count <= total) {
this.destination.next(value);
if (count === total) {
this.destination.complete();
this.unsubscribe();
}
}
}
}
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