100 lines
3.5 KiB
JavaScript
100 lines
3.5 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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/**
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* Returns an Observable that emits the first item of the source Observable that matches the specified condition.
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* Throws an error if matching element is not found.
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* @param {function} predicate function called with each item to test for condition matching.
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* @returns {Observable} an Observable of the first item that matches the condition.
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*/
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function first(predicate, resultSelector, defaultValue) {
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return this.lift(new FirstOperator(predicate, resultSelector, defaultValue, this));
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}
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exports.first = first;
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var FirstOperator = (function () {
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function FirstOperator(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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FirstOperator.prototype.call = function (observer) {
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return new FirstSubscriber(observer, this.predicate, this.resultSelector, this.defaultValue, this.source);
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};
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return FirstOperator;
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}());
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var FirstSubscriber = (function (_super) {
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__extends(FirstSubscriber, _super);
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function FirstSubscriber(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.index = 0;
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this.hasCompleted = false;
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}
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FirstSubscriber.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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this._emit(value, index);
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}
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};
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FirstSubscriber.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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this._emit(value, index);
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}
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};
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FirstSubscriber.prototype._emit = function (value, index) {
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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._emitFinal(value);
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};
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FirstSubscriber.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._emitFinal(result);
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};
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FirstSubscriber.prototype._emitFinal = function (value) {
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var destination = this.destination;
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destination.next(value);
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destination.complete();
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this.hasCompleted = true;
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};
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FirstSubscriber.prototype._complete = function () {
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var destination = this.destination;
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if (!this.hasCompleted && typeof this.defaultValue !== 'undefined') {
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destination.next(this.defaultValue);
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destination.complete();
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}
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else if (!this.hasCompleted) {
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destination.error(new EmptyError_1.EmptyError);
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}
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};
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return FirstSubscriber;
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}(Subscriber_1.Subscriber));
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//# sourceMappingURL=first.js.map
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