77 lines
2.9 KiB
JavaScript
77 lines
2.9 KiB
JavaScript
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"use strict";
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var __extends = (this && this.__extends) || function (d, b) {
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for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
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function __() { this.constructor = d; }
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d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
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};
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var Subscriber_1 = require('../Subscriber');
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/* tslint:enable:max-line-length */
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/**
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* Emits a given value if the source Observable completes without emitting any
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* `next` value, otherwise mirrors the source Observable.
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*
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* <span class="informal">If the source Observable turns out to be empty, then
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* this operator will emit a default value.</span>
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*
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* <img src="./img/defaultIfEmpty.png" width="100%">
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*
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* `defaultIfEmpty` emits the values emitted by the source Observable or a
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* specified default value if the source Observable is empty (completes without
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* having emitted any `next` value).
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*
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* @example <caption>If no clicks happen in 5 seconds, then emit "no clicks"</caption>
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* var clicks = Rx.Observable.fromEvent(document, 'click');
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* var clicksBeforeFive = clicks.takeUntil(Rx.Observable.interval(5000));
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* var result = clicksBeforeFive.defaultIfEmpty('no clicks');
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* result.subscribe(x => console.log(x));
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*
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* @see {@link empty}
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* @see {@link last}
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*
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* @param {any} [defaultValue=null] The default value used if the source
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* Observable is empty.
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* @return {Observable} An Observable that emits either the specified
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* `defaultValue` if the source Observable emits no items, or the values emitted
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* by the source Observable.
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* @method defaultIfEmpty
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* @owner Observable
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*/
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function defaultIfEmpty(defaultValue) {
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if (defaultValue === void 0) { defaultValue = null; }
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return function (source) { return source.lift(new DefaultIfEmptyOperator(defaultValue)); };
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}
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exports.defaultIfEmpty = defaultIfEmpty;
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var DefaultIfEmptyOperator = (function () {
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function DefaultIfEmptyOperator(defaultValue) {
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this.defaultValue = defaultValue;
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}
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DefaultIfEmptyOperator.prototype.call = function (subscriber, source) {
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return source.subscribe(new DefaultIfEmptySubscriber(subscriber, this.defaultValue));
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};
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return DefaultIfEmptyOperator;
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}());
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/**
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* We need this JSDoc comment for affecting ESDoc.
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* @ignore
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* @extends {Ignored}
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*/
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var DefaultIfEmptySubscriber = (function (_super) {
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__extends(DefaultIfEmptySubscriber, _super);
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function DefaultIfEmptySubscriber(destination, defaultValue) {
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_super.call(this, destination);
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this.defaultValue = defaultValue;
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this.isEmpty = true;
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}
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DefaultIfEmptySubscriber.prototype._next = function (value) {
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this.isEmpty = false;
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this.destination.next(value);
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};
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DefaultIfEmptySubscriber.prototype._complete = function () {
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if (this.isEmpty) {
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this.destination.next(this.defaultValue);
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}
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this.destination.complete();
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};
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return DefaultIfEmptySubscriber;
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}(Subscriber_1.Subscriber));
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//# sourceMappingURL=defaultIfEmpty.js.map
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