work.suroh.tk/node_modules/rxjs/operators/defaultIfEmpty.js

77 lines
2.9 KiB
JavaScript

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