@reactivex/rxjs
Version:
Reactive Extensions for modern JavaScript
114 lines • 3.7 kB
JavaScript
;
var __extends = (this && this.__extends) || (function () {
var extendStatics = function (d, b) {
extendStatics = Object.setPrototypeOf ||
({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };
return extendStatics(d, b);
}
return function (d, b) {
extendStatics(d, b);
function __() { this.constructor = d; }
d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
};
})();
Object.defineProperty(exports, "__esModule", { value: true });
var Subscriber_1 = require("../Subscriber");
var ArgumentOutOfRangeError_1 = require("../util/ArgumentOutOfRangeError");
var empty_1 = require("../observable/empty");
/**
* 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` 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
*/
function take(count) {
return function (source) {
if (count === 0) {
return empty_1.empty();
}
else {
return source.lift(new TakeOperator(count));
}
};
}
exports.take = take;
var TakeOperator = /** @class */ (function () {
function TakeOperator(total) {
this.total = total;
if (this.total < 0) {
throw new ArgumentOutOfRangeError_1.ArgumentOutOfRangeError;
}
}
TakeOperator.prototype.call = function (subscriber, source) {
return source.subscribe(new TakeSubscriber(subscriber, this.total));
};
return TakeOperator;
}());
/**
* We need this JSDoc comment for affecting ESDoc.
* @ignore
* @extends {Ignored}
*/
var TakeSubscriber = /** @class */ (function (_super) {
__extends(TakeSubscriber, _super);
function TakeSubscriber(destination, total) {
var _this = _super.call(this, destination) || this;
_this.total = total;
_this.count = 0;
return _this;
}
TakeSubscriber.prototype._next = function (value) {
var total = this.total;
var count = ++this.count;
if (count <= total) {
this.destination.next(value);
if (count === total) {
this.destination.complete();
this.unsubscribe();
}
}
};
return TakeSubscriber;
}(Subscriber_1.Subscriber));
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