import { Operator } from '../Operator';
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import { Subscriber } from '../Subscriber';
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import { Observable } from '../Observable';
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import { ObservableInput, OperatorFunction, ObservedValueOf } from '../types';
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import { SimpleOuterSubscriber, SimpleInnerSubscriber, innerSubscribe } from '../innerSubscribe';
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/* tslint:disable:max-line-length */
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export function catchError<T, O extends ObservableInput<any>>(selector: (err: any, caught: Observable<T>) => O): OperatorFunction<T, T | ObservedValueOf<O>>;
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/* tslint:enable:max-line-length */
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/**
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* Catches errors on the observable to be handled by returning a new observable or throwing an error.
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*
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* 
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*
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* ## Examples
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* Continues with a different Observable when there's an error
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*
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* ```ts
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* import { of } from 'rxjs';
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* import { map, catchError } from 'rxjs/operators';
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*
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* of(1, 2, 3, 4, 5).pipe(
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* map(n => {
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* if (n === 4) {
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* throw 'four!';
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* }
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* return n;
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* }),
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* catchError(err => of('I', 'II', 'III', 'IV', 'V')),
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* )
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* .subscribe(x => console.log(x));
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* // 1, 2, 3, I, II, III, IV, V
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* ```
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*
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* Retries the caught source Observable again in case of error, similar to retry() operator
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*
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* ```ts
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* import { of } from 'rxjs';
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* import { map, catchError, take } from 'rxjs/operators';
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*
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* of(1, 2, 3, 4, 5).pipe(
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* map(n => {
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* if (n === 4) {
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* throw 'four!';
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* }
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* return n;
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* }),
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* catchError((err, caught) => caught),
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* take(30),
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* )
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* .subscribe(x => console.log(x));
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* // 1, 2, 3, 1, 2, 3, ...
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* ```
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*
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* Throws a new error when the source Observable throws an error
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*
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* ```ts
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* import { of } from 'rxjs';
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* import { map, catchError } from 'rxjs/operators';
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*
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* of(1, 2, 3, 4, 5).pipe(
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* map(n => {
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* if (n === 4) {
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* throw 'four!';
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* }
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* return n;
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* }),
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* catchError(err => {
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* throw 'error in source. Details: ' + err;
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* }),
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* )
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* .subscribe(
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* x => console.log(x),
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* err => console.log(err)
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* );
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* // 1, 2, 3, error in source. Details: four!
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* ```
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*
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* @param {function} selector a function that takes as arguments `err`, which is the error, and `caught`, which
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* is the source observable, in case you'd like to "retry" that observable by returning it again. Whatever observable
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* is returned by the `selector` will be used to continue the observable chain.
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* @return {Observable} An observable that originates from either the source or the observable returned by the
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* catch `selector` function.
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* @name catchError
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*/
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export function catchError<T, O extends ObservableInput<any>>(
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selector: (err: any, caught: Observable<T>) => O
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): OperatorFunction<T, T | ObservedValueOf<O>> {
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return function catchErrorOperatorFunction(source: Observable<T>): Observable<T | ObservedValueOf<O>> {
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const operator = new CatchOperator(selector);
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const caught = source.lift(operator);
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return (operator.caught = caught as Observable<T>);
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};
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}
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class CatchOperator<T, R> implements Operator<T, T | R> {
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caught: Observable<T>;
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constructor(private selector: (err: any, caught: Observable<T>) => ObservableInput<T | R>) {
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}
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call(subscriber: Subscriber<R>, source: any): any {
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return source.subscribe(new CatchSubscriber(subscriber, this.selector, this.caught));
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}
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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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class CatchSubscriber<T, R> extends SimpleOuterSubscriber<T, T | R> {
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constructor(destination: Subscriber<any>,
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private selector: (err: any, caught: Observable<T>) => ObservableInput<T | R>,
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private caught: Observable<T>) {
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super(destination);
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}
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// NOTE: overriding `error` instead of `_error` because we don't want
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// to have this flag this subscriber as `isStopped`. We can mimic the
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// behavior of the RetrySubscriber (from the `retry` operator), where
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// we unsubscribe from our source chain, reset our Subscriber flags,
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// then subscribe to the selector result.
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error(err: any) {
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if (!this.isStopped) {
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let result: any;
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try {
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result = this.selector(err, this.caught);
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} catch (err2) {
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super.error(err2);
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return;
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}
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this._unsubscribeAndRecycle();
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const innerSubscriber = new SimpleInnerSubscriber(this);
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this.add(innerSubscriber);
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const innerSubscription = innerSubscribe(result, innerSubscriber);
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// The returned subscription will usually be the subscriber that was
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// passed. However, interop subscribers will be wrapped and for
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// unsubscriptions to chain correctly, the wrapper needs to be added, too.
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if (innerSubscription !== innerSubscriber) {
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this.add(innerSubscription);
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}
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}
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}
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}
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