111 lines
4.0 KiB
JavaScript
Executable File
111 lines
4.0 KiB
JavaScript
Executable File
/** PURE_IMPORTS_START .._Subscriber,.._util_ArgumentOutOfRangeError,.._observable_EmptyObservable PURE_IMPORTS_END */
|
|
var __extends = (this && this.__extends) || function (d, b) {
|
|
for (var p in b)
|
|
if (b.hasOwnProperty(p))
|
|
d[p] = b[p];
|
|
function __() { this.constructor = d; }
|
|
d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
|
|
};
|
|
import { Subscriber } from '../Subscriber';
|
|
import { ArgumentOutOfRangeError } from '../util/ArgumentOutOfRangeError';
|
|
import { EmptyObservable } from '../observable/EmptyObservable';
|
|
/**
|
|
* Emits only the last `count` values emitted by the source Observable.
|
|
*
|
|
* <span class="informal">Remembers the latest `count` values, then emits those
|
|
* only when the source completes.</span>
|
|
*
|
|
* <img src="./img/takeLast.png" width="100%">
|
|
*
|
|
* `takeLast` returns an Observable that emits at most the last `count` values
|
|
* emitted by the source Observable. If the source emits fewer than `count`
|
|
* values then all of its values are emitted. This operator must wait until the
|
|
* `complete` notification emission from the source in order to emit the `next`
|
|
* values on the output Observable, because otherwise it is impossible to know
|
|
* whether or not more values will be emitted on the source. For this reason,
|
|
* all values are emitted synchronously, followed by the complete notification.
|
|
*
|
|
* @example <caption>Take the last 3 values of an Observable with many values</caption>
|
|
* var many = Rx.Observable.range(1, 100);
|
|
* var lastThree = many.takeLast(3);
|
|
* lastThree.subscribe(x => console.log(x));
|
|
*
|
|
* @see {@link take}
|
|
* @see {@link takeUntil}
|
|
* @see {@link takeWhile}
|
|
* @see {@link skip}
|
|
*
|
|
* @throws {ArgumentOutOfRangeError} When using `takeLast(i)`, it delivers an
|
|
* ArgumentOutOrRangeError to the Observer's `error` callback if `i < 0`.
|
|
*
|
|
* @param {number} count The maximum number of values to emit from the end of
|
|
* the sequence of values emitted by the source Observable.
|
|
* @return {Observable<T>} An Observable that emits at most the last count
|
|
* values emitted by the source Observable.
|
|
* @method takeLast
|
|
* @owner Observable
|
|
*/
|
|
export function takeLast(count) {
|
|
return function takeLastOperatorFunction(source) {
|
|
if (count === 0) {
|
|
return new EmptyObservable();
|
|
}
|
|
else {
|
|
return source.lift(new TakeLastOperator(count));
|
|
}
|
|
};
|
|
}
|
|
var TakeLastOperator = /*@__PURE__*/ (/*@__PURE__*/ function () {
|
|
function TakeLastOperator(total) {
|
|
this.total = total;
|
|
if (this.total < 0) {
|
|
throw new ArgumentOutOfRangeError;
|
|
}
|
|
}
|
|
TakeLastOperator.prototype.call = function (subscriber, source) {
|
|
return source.subscribe(new TakeLastSubscriber(subscriber, this.total));
|
|
};
|
|
return TakeLastOperator;
|
|
}());
|
|
/**
|
|
* We need this JSDoc comment for affecting ESDoc.
|
|
* @ignore
|
|
* @extends {Ignored}
|
|
*/
|
|
var TakeLastSubscriber = /*@__PURE__*/ (/*@__PURE__*/ function (_super) {
|
|
__extends(TakeLastSubscriber, _super);
|
|
function TakeLastSubscriber(destination, total) {
|
|
_super.call(this, destination);
|
|
this.total = total;
|
|
this.ring = new Array();
|
|
this.count = 0;
|
|
}
|
|
TakeLastSubscriber.prototype._next = function (value) {
|
|
var ring = this.ring;
|
|
var total = this.total;
|
|
var count = this.count++;
|
|
if (ring.length < total) {
|
|
ring.push(value);
|
|
}
|
|
else {
|
|
var index = count % total;
|
|
ring[index] = value;
|
|
}
|
|
};
|
|
TakeLastSubscriber.prototype._complete = function () {
|
|
var destination = this.destination;
|
|
var count = this.count;
|
|
if (count > 0) {
|
|
var total = this.count >= this.total ? this.total : this.count;
|
|
var ring = this.ring;
|
|
for (var i = 0; i < total; i++) {
|
|
var idx = (count++) % total;
|
|
destination.next(ring[idx]);
|
|
}
|
|
}
|
|
destination.complete();
|
|
};
|
|
return TakeLastSubscriber;
|
|
}(Subscriber));
|
|
//# sourceMappingURL=takeLast.js.map
|