takeLast.js 2.68 KB
"use strict";
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");
function takeLast(count) {
    return function takeLastOperatorFunction(source) {
        if (count === 0) {
            return empty_1.empty();
        }
        else {
            return source.lift(new TakeLastOperator(count));
        }
    };
}
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;
}());
var TakeLastSubscriber = (function (_super) {
    __extends(TakeLastSubscriber, _super);
    function TakeLastSubscriber(destination, total) {
        var _this = _super.call(this, destination) || this;
        _this.total = total;
        _this.ring = new Array();
        _this.count = 0;
        return _this;
    }
    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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