@reactivex/rxjs/dist/amd/operator/takeLast.js

Reactive Extensions for modern JavaScript

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 __());
};
define(["require", "exports", '../Subscriber', '../util/ArgumentOutOfRangeError', '../observable/EmptyObservable'], function (require, exports, Subscriber_1, ArgumentOutOfRangeError_1, EmptyObservable_1) {
    "use strict";
    /**
     * @throws {ArgumentOutOfRangeError} When using `takeLast(i)`, it delivers an
     * ArgumentOutOrRangeError to the Observer's `error` callback if `i < 0`.
     * @param total
     * @return {any}
     * @method takeLast
     * @owner Observable
     */
    function takeLast(total) {
        if (total === 0) {
            return new EmptyObservable_1.EmptyObservable();
        }
        else {
            return this.lift(new TakeLastOperator(total));
        }
    }
    exports.takeLast = takeLast;
    var TakeLastOperator = (function () {
        function TakeLastOperator(total) {
            this.total = total;
            if (this.total < 0) {
                throw new ArgumentOutOfRangeError_1.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 = (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_1.Subscriber));
});
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