@acutmore/rxjs
Version:
Reactive Extensions for modern JavaScript
98 lines • 3.63 kB
JavaScript
var __extends = (this && this.__extends) || (function () {
var 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 function (d, b) {
extendStatics(d, b);
function __() { this.constructor = d; }
d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
};
})();
import { Subscriber } from '../Subscriber';
import { EmptyError } from '..//util/EmptyError';
/**
* Returns an Observable that emits the single item emitted by the source Observable that matches a specified
* predicate, if that Observable emits one such item. If the source Observable emits more than one such item or no
* such items, notify of an IllegalArgumentException or NoSuchElementException respectively.
*
* <img src="./img/single.png" width="100%">
*
* @throws {EmptyError} Delivers an EmptyError to the Observer's `error`
* callback if the Observable completes before any `next` notification was sent.
* @param {Function} predicate - A predicate function to evaluate items emitted by the source Observable.
* @return {Observable<T>} An Observable that emits the single item emitted by the source Observable that matches
* the predicate.
.
* @method single
* @owner Observable
*/
export function single(predicate) {
return function (source) { return source.lift(new SingleOperator(predicate, source)); };
}
var SingleOperator = /** @class */ (function () {
function SingleOperator(predicate, source) {
this.predicate = predicate;
this.source = source;
}
SingleOperator.prototype.call = function (subscriber, source) {
return source.subscribe(new SingleSubscriber(subscriber, this.predicate, this.source));
};
return SingleOperator;
}());
/**
* We need this JSDoc comment for affecting ESDoc.
* @ignore
* @extends {Ignored}
*/
var SingleSubscriber = /** @class */ (function (_super) {
__extends(SingleSubscriber, _super);
function SingleSubscriber(destination, predicate, source) {
var _this = _super.call(this, destination) || this;
_this.predicate = predicate;
_this.source = source;
_this.seenValue = false;
_this.index = 0;
return _this;
}
SingleSubscriber.prototype.applySingleValue = function (value) {
if (this.seenValue) {
this.destination.error('Sequence contains more than one element');
}
else {
this.seenValue = true;
this.singleValue = value;
}
};
SingleSubscriber.prototype._next = function (value) {
var index = this.index++;
if (this.predicate) {
this.tryNext(value, index);
}
else {
this.applySingleValue(value);
}
};
SingleSubscriber.prototype.tryNext = function (value, index) {
try {
if (this.predicate(value, index, this.source)) {
this.applySingleValue(value);
}
}
catch (err) {
this.destination.error(err);
}
};
SingleSubscriber.prototype._complete = function () {
var destination = this.destination;
// v4-backwards-compatibility
if (this.seenValue) {
destination.next(this.singleValue);
destination.complete();
}
else {
destination.error(new EmptyError);
}
};
return SingleSubscriber;
}(Subscriber));
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