@reactivex/rxjs/dist-compat/cjs/src/internal/operators/withLatestFrom.js

Reactive Extensions for modern JavaScript

"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 OuterSubscriber_1 = require("../OuterSubscriber");
var subscribeToResult_1 = require("../util/subscribeToResult");
/* tslint:enable:max-line-length */
/**
 * Combines the source Observable with other Observables to create an Observable
 * whose values are calculated from the latest values of each, only when the
 * source emits.
 *
 * <span class="informal">Whenever the source Observable emits a value, it
 * computes a formula using that value plus the latest values from other input
 * Observables, then emits the output of that formula.</span>
 *
 * ![](withLatestFrom.png)
 *
 * `withLatestFrom` combines each value from the source Observable (the
 * instance) with the latest values from the other input Observables only when
 * the source emits a value, optionally using a `project` function to determine
 * the value to be emitted on the output Observable. All input Observables must
 * emit at least one value before the output Observable will emit a value.
 *
 * ## Example
 * On every click event, emit an array with the latest timer event plus the click event
 * ```ts
 * import { fromEvent, interval } from 'rxjs';
 * import { withLatestFrom } from 'rxjs/operators';
 *
 * const clicks = fromEvent(document, 'click');
 * const timer = interval(1000);
 * const result = clicks.pipe(withLatestFrom(timer));
 * result.subscribe(x => console.log(x));
 * ```
 *
 * @see {@link combineLatest}
 *
 * @param {ObservableInput} other An input Observable to combine with the source
 * Observable. More than one input Observables may be given as argument.
 * @param {Function} [project] Projection function for combining values
 * together. Receives all values in order of the Observables passed, where the
 * first parameter is a value from the source Observable. (e.g.
 * `a.pipe(withLatestFrom(b, c), map(([a1, b1, c1]) => a1 + b1 + c1))`). If this is not
 * passed, arrays will be emitted on the output Observable.
 * @return {Observable} An Observable of projected values from the most recent
 * values from each input Observable, or an array of the most recent values from
 * each input Observable.
 * @method withLatestFrom
 * @owner Observable
 */
function withLatestFrom() {
    var args = [];
    for (var _i = 0; _i < arguments.length; _i++) {
        args[_i] = arguments[_i];
    }
    return function (source) {
        var project;
        if (typeof args[args.length - 1] === 'function') {
            project = args.pop();
        }
        var observables = args;
        return source.lift(new WithLatestFromOperator(observables, project));
    };
}
exports.withLatestFrom = withLatestFrom;
var WithLatestFromOperator = /** @class */ (function () {
    function WithLatestFromOperator(observables, project) {
        this.observables = observables;
        this.project = project;
    }
    WithLatestFromOperator.prototype.call = function (subscriber, source) {
        return source.subscribe(new WithLatestFromSubscriber(subscriber, this.observables, this.project));
    };
    return WithLatestFromOperator;
}());
/**
 * We need this JSDoc comment for affecting ESDoc.
 * @ignore
 * @extends {Ignored}
 */
var WithLatestFromSubscriber = /** @class */ (function (_super) {
    __extends(WithLatestFromSubscriber, _super);
    function WithLatestFromSubscriber(destination, observables, project) {
        var _this = _super.call(this, destination) || this;
        _this.observables = observables;
        _this.project = project;
        _this.toRespond = [];
        var len = observables.length;
        _this.values = new Array(len);
        for (var i = 0; i < len; i++) {
            _this.toRespond.push(i);
        }
        for (var i = 0; i < len; i++) {
            var observable = observables[i];
            _this.add(subscribeToResult_1.subscribeToResult(_this, observable, undefined, i));
        }
        return _this;
    }
    WithLatestFromSubscriber.prototype.notifyNext = function (_outerValue, innerValue, outerIndex) {
        this.values[outerIndex] = innerValue;
        var toRespond = this.toRespond;
        if (toRespond.length > 0) {
            var found = toRespond.indexOf(outerIndex);
            if (found !== -1) {
                toRespond.splice(found, 1);
            }
        }
    };
    WithLatestFromSubscriber.prototype.notifyComplete = function () {
        // noop
    };
    WithLatestFromSubscriber.prototype._next = function (value) {
        if (this.toRespond.length === 0) {
            var args = [value].concat(this.values);
            if (this.project) {
                this._tryProject(args);
            }
            else {
                this.destination.next(args);
            }
        }
    };
    WithLatestFromSubscriber.prototype._tryProject = function (args) {
        var result;
        try {
            result = this.project.apply(this, args);
        }
        catch (err) {
            this.destination.error(err);
            return;
        }
        this.destination.next(result);
    };
    return WithLatestFromSubscriber;
}(OuterSubscriber_1.OuterSubscriber));
//# sourceMappingURL=withLatestFrom.js.map