es6/operator/scan.js

import { Subscriber } from '../Subscriber';
/* tslint:disable:max-line-length */
export function scan(accumulator, seed) {
    var hasSeed = false;
    // providing a seed of `undefined` *should* be valid and trigger
    // hasSeed! so don't use `seed !== undefined` checks!
    // For this reason, we have to check it here at the original call site
    // otherwise inside Operator/Subscriber we won't know if `undefined`
    // means they didn't provide anything or if they literally provided `undefined`
    if (arguments.length >= 2) {
        hasSeed = true;
    }
    return this.lift(new ScanOperator(accumulator, seed, hasSeed));
}
var ScanOperator = (function () {
    function ScanOperator(accumulator, seed, hasSeed) {
        if (hasSeed === void 0) { hasSeed = false; }
        this.accumulator = accumulator;
        this.seed = seed;
        this.hasSeed = hasSeed;
    }
    ScanOperator.prototype.call = function (subscriber, source) {
        return source._subscribe(new ScanSubscriber(subscriber, this.accumulator, this.seed, this.hasSeed));
    };
    return ScanOperator;
}());
/**
 * We need this JSDoc comment for affecting ESDoc.
 * @ignore
 * @extends {Ignored}
 */
var ScanSubscriber = (function (_super) {
    __extends(ScanSubscriber, _super);
    function ScanSubscriber(destination, accumulator, _seed, hasSeed) {
        _super.call(this, destination);
        this.accumulator = accumulator;
        this._seed = _seed;
        this.hasSeed = hasSeed;
        this.index = 0;
    }
    Object.defineProperty(ScanSubscriber.prototype, "seed", {
        get: function () {
            return this._seed;
        },
        set: function (value) {
            this.hasSeed = true;
            this._seed = value;
        },
        enumerable: true,
        configurable: true
    });
    ScanSubscriber.prototype._next = function (value) {
        if (!this.hasSeed) {
            this.seed = value;
            this.destination.next(value);
        }
        else {
            return this._tryNext(value);
        }
    };
    ScanSubscriber.prototype._tryNext = function (value) {
        var index = this.index++;
        var result;
        try {
            result = this.accumulator(this.seed, value, index);
        }
        catch (err) {
            this.destination.error(err);
        }
        this.seed = result;
        this.destination.next(result);
    };
    return ScanSubscriber;
}(Subscriber));
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