119 lines
4.3 KiB
JavaScript
119 lines
4.3 KiB
JavaScript
"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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var EmptyError_1 = require('../util/EmptyError');
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/* tslint:enable:max-line-length */
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/**
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* Returns an Observable that emits only the last item emitted by the source Observable.
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* It optionally takes a predicate function as a parameter, in which case, rather than emitting
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* the last item from the source Observable, the resulting Observable will emit the last item
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* from the source Observable that satisfies the predicate.
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*
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* <img src="./img/last.png" width="100%">
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*
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* @throws {EmptyError} Delivers an EmptyError to the Observer's `error`
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* callback if the Observable completes before any `next` notification was sent.
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* @param {function} predicate - The condition any source emitted item has to satisfy.
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* @return {Observable} An Observable that emits only the last item satisfying the given condition
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* from the source, or an NoSuchElementException if no such items are emitted.
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* @throws - Throws if no items that match the predicate are emitted by the source Observable.
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* @method last
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* @owner Observable
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*/
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function last(predicate, resultSelector, defaultValue) {
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return function (source) { return source.lift(new LastOperator(predicate, resultSelector, defaultValue, source)); };
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}
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exports.last = last;
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var LastOperator = (function () {
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function LastOperator(predicate, resultSelector, defaultValue, source) {
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this.predicate = predicate;
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this.resultSelector = resultSelector;
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this.defaultValue = defaultValue;
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this.source = source;
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}
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LastOperator.prototype.call = function (observer, source) {
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return source.subscribe(new LastSubscriber(observer, this.predicate, this.resultSelector, this.defaultValue, this.source));
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};
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return LastOperator;
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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 LastSubscriber = (function (_super) {
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__extends(LastSubscriber, _super);
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function LastSubscriber(destination, predicate, resultSelector, defaultValue, source) {
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_super.call(this, destination);
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this.predicate = predicate;
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this.resultSelector = resultSelector;
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this.defaultValue = defaultValue;
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this.source = source;
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this.hasValue = false;
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this.index = 0;
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if (typeof defaultValue !== 'undefined') {
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this.lastValue = defaultValue;
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this.hasValue = true;
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}
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}
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LastSubscriber.prototype._next = function (value) {
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var index = this.index++;
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if (this.predicate) {
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this._tryPredicate(value, index);
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}
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else {
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if (this.resultSelector) {
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this._tryResultSelector(value, index);
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return;
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}
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this.lastValue = value;
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this.hasValue = true;
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}
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};
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LastSubscriber.prototype._tryPredicate = function (value, index) {
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var result;
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try {
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result = this.predicate(value, index, this.source);
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}
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catch (err) {
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this.destination.error(err);
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return;
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}
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if (result) {
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if (this.resultSelector) {
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this._tryResultSelector(value, index);
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return;
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}
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this.lastValue = value;
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this.hasValue = true;
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}
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};
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LastSubscriber.prototype._tryResultSelector = function (value, index) {
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var result;
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try {
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result = this.resultSelector(value, index);
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}
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catch (err) {
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this.destination.error(err);
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return;
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}
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this.lastValue = result;
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this.hasValue = true;
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};
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LastSubscriber.prototype._complete = function () {
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var destination = this.destination;
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if (this.hasValue) {
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destination.next(this.lastValue);
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destination.complete();
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}
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else {
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destination.error(new EmptyError_1.EmptyError);
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}
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};
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return LastSubscriber;
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}(Subscriber_1.Subscriber));
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//# sourceMappingURL=last.js.map
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