import { Operator } from './Operator';
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import { Subscriber } from './Subscriber';
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import { Subscription } from './Subscription';
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import { TeardownLogic, OperatorFunction, PartialObserver, Subscribable } from './types';
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import { canReportError } from './util/canReportError';
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import { toSubscriber } from './util/toSubscriber';
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import { iif } from './observable/iif';
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import { throwError } from './observable/throwError';
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import { observable as Symbol_observable } from './symbol/observable';
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import { pipeFromArray } from './util/pipe';
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import { config } from './config';
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/**
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* A representation of any set of values over any amount of time. This is the most basic building block
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* of RxJS.
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*
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* @class Observable<T>
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*/
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export class Observable<T> implements Subscribable<T> {
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/** Internal implementation detail, do not use directly. */
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public _isScalar: boolean = false;
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/** @deprecated This is an internal implementation detail, do not use. */
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source: Observable<any>;
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/** @deprecated This is an internal implementation detail, do not use. */
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operator: Operator<any, T>;
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/**
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* @constructor
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* @param {Function} subscribe the function that is called when the Observable is
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* initially subscribed to. This function is given a Subscriber, to which new values
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* can be `next`ed, or an `error` method can be called to raise an error, or
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* `complete` can be called to notify of a successful completion.
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*/
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constructor(subscribe?: (this: Observable<T>, subscriber: Subscriber<T>) => TeardownLogic) {
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if (subscribe) {
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this._subscribe = subscribe;
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}
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}
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// HACK: Since TypeScript inherits static properties too, we have to
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// fight against TypeScript here so Subject can have a different static create signature
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/**
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* Creates a new cold Observable by calling the Observable constructor
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* @static true
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* @owner Observable
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* @method create
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* @param {Function} subscribe? the subscriber function to be passed to the Observable constructor
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* @return {Observable} a new cold observable
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* @nocollapse
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* @deprecated use new Observable() instead
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*/
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static create: Function = <T>(subscribe?: (subscriber: Subscriber<T>) => TeardownLogic) => {
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return new Observable<T>(subscribe);
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}
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/**
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* Creates a new Observable, with this Observable as the source, and the passed
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* operator defined as the new observable's operator.
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* @method lift
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* @param {Operator} operator the operator defining the operation to take on the observable
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* @return {Observable} a new observable with the Operator applied
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*/
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lift<R>(operator: Operator<T, R>): Observable<R> {
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const observable = new Observable<R>();
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observable.source = this;
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observable.operator = operator;
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return observable;
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}
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subscribe(observer?: PartialObserver<T>): Subscription;
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/** @deprecated Use an observer instead of a complete callback */
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subscribe(next: null | undefined, error: null | undefined, complete: () => void): Subscription;
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/** @deprecated Use an observer instead of an error callback */
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subscribe(next: null | undefined, error: (error: any) => void, complete?: () => void): Subscription;
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/** @deprecated Use an observer instead of a complete callback */
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subscribe(next: (value: T) => void, error: null | undefined, complete: () => void): Subscription;
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subscribe(next?: (value: T) => void, error?: (error: any) => void, complete?: () => void): Subscription;
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/**
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* Invokes an execution of an Observable and registers Observer handlers for notifications it will emit.
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*
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* <span class="informal">Use it when you have all these Observables, but still nothing is happening.</span>
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*
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* `subscribe` is not a regular operator, but a method that calls Observable's internal `subscribe` function. It
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* might be for example a function that you passed to Observable's constructor, but most of the time it is
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* a library implementation, which defines what will be emitted by an Observable, and when it be will emitted. This means
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* that calling `subscribe` is actually the moment when Observable starts its work, not when it is created, as it is often
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* the thought.
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*
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* Apart from starting the execution of an Observable, this method allows you to listen for values
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* that an Observable emits, as well as for when it completes or errors. You can achieve this in two
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* of the following ways.
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*
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* The first way is creating an object that implements {@link Observer} interface. It should have methods
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* defined by that interface, but note that it should be just a regular JavaScript object, which you can create
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* yourself in any way you want (ES6 class, classic function constructor, object literal etc.). In particular do
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* not attempt to use any RxJS implementation details to create Observers - you don't need them. Remember also
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* that your object does not have to implement all methods. If you find yourself creating a method that doesn't
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* do anything, you can simply omit it. Note however, if the `error` method is not provided, all errors will
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* be left uncaught.
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*
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* The second way is to give up on Observer object altogether and simply provide callback functions in place of its methods.
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* This means you can provide three functions as arguments to `subscribe`, where the first function is equivalent
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* of a `next` method, the second of an `error` method and the third of a `complete` method. Just as in case of Observer,
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* if you do not need to listen for something, you can omit a function, preferably by passing `undefined` or `null`,
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* since `subscribe` recognizes these functions by where they were placed in function call. When it comes
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* to `error` function, just as before, if not provided, errors emitted by an Observable will be thrown.
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*
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* Whichever style of calling `subscribe` you use, in both cases it returns a Subscription object.
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* This object allows you to call `unsubscribe` on it, which in turn will stop the work that an Observable does and will clean
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* up all resources that an Observable used. Note that cancelling a subscription will not call `complete` callback
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* provided to `subscribe` function, which is reserved for a regular completion signal that comes from an Observable.
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*
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* Remember that callbacks provided to `subscribe` are not guaranteed to be called asynchronously.
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* It is an Observable itself that decides when these functions will be called. For example {@link of}
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* by default emits all its values synchronously. Always check documentation for how given Observable
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* will behave when subscribed and if its default behavior can be modified with a `scheduler`.
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*
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* ## Example
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* ### Subscribe with an Observer
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* ```ts
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* import { of } from 'rxjs';
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*
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* const sumObserver = {
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* sum: 0,
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* next(value) {
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* console.log('Adding: ' + value);
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* this.sum = this.sum + value;
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* },
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* error() {
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* // We actually could just remove this method,
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* // since we do not really care about errors right now.
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* },
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* complete() {
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* console.log('Sum equals: ' + this.sum);
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* }
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* };
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*
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* of(1, 2, 3) // Synchronously emits 1, 2, 3 and then completes.
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* .subscribe(sumObserver);
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*
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* // Logs:
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* // "Adding: 1"
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* // "Adding: 2"
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* // "Adding: 3"
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* // "Sum equals: 6"
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* ```
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*
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* ### Subscribe with functions
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* ```ts
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* import { of } from 'rxjs'
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*
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* let sum = 0;
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*
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* of(1, 2, 3).subscribe(
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* value => {
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* console.log('Adding: ' + value);
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* sum = sum + value;
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* },
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* undefined,
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* () => console.log('Sum equals: ' + sum)
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* );
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*
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* // Logs:
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* // "Adding: 1"
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* // "Adding: 2"
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* // "Adding: 3"
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* // "Sum equals: 6"
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* ```
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*
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* ### Cancel a subscription
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* ```ts
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* import { interval } from 'rxjs';
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*
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* const subscription = interval(1000).subscribe(
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* num => console.log(num),
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* undefined,
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* () => {
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* // Will not be called, even when cancelling subscription.
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* console.log('completed!');
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* }
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* );
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*
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* setTimeout(() => {
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* subscription.unsubscribe();
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* console.log('unsubscribed!');
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* }, 2500);
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*
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* // Logs:
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* // 0 after 1s
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* // 1 after 2s
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* // "unsubscribed!" after 2.5s
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* ```
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*
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* @param {Observer|Function} observerOrNext (optional) Either an observer with methods to be called,
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* or the first of three possible handlers, which is the handler for each value emitted from the subscribed
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* Observable.
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* @param {Function} error (optional) A handler for a terminal event resulting from an error. If no error handler is provided,
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* the error will be thrown as unhandled.
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* @param {Function} complete (optional) A handler for a terminal event resulting from successful completion.
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* @return {ISubscription} a subscription reference to the registered handlers
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* @method subscribe
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*/
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subscribe(observerOrNext?: PartialObserver<T> | ((value: T) => void),
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error?: (error: any) => void,
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complete?: () => void): Subscription {
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const { operator } = this;
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const sink = toSubscriber(observerOrNext, error, complete);
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if (operator) {
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sink.add(operator.call(sink, this.source));
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} else {
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sink.add(
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this.source || (config.useDeprecatedSynchronousErrorHandling && !sink.syncErrorThrowable) ?
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this._subscribe(sink) :
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this._trySubscribe(sink)
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);
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}
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if (config.useDeprecatedSynchronousErrorHandling) {
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if (sink.syncErrorThrowable) {
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sink.syncErrorThrowable = false;
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if (sink.syncErrorThrown) {
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throw sink.syncErrorValue;
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}
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}
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}
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return sink;
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}
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/** @deprecated This is an internal implementation detail, do not use. */
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_trySubscribe(sink: Subscriber<T>): TeardownLogic {
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try {
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return this._subscribe(sink);
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} catch (err) {
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if (config.useDeprecatedSynchronousErrorHandling) {
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sink.syncErrorThrown = true;
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sink.syncErrorValue = err;
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}
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if (canReportError(sink)) {
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sink.error(err);
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} else {
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console.warn(err);
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}
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}
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}
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/**
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* @method forEach
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* @param {Function} next a handler for each value emitted by the observable
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* @param {PromiseConstructor} [promiseCtor] a constructor function used to instantiate the Promise
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* @return {Promise} a promise that either resolves on observable completion or
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* rejects with the handled error
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*/
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forEach(next: (value: T) => void, promiseCtor?: PromiseConstructorLike): Promise<void> {
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promiseCtor = getPromiseCtor(promiseCtor);
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return new promiseCtor<void>((resolve, reject) => {
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// Must be declared in a separate statement to avoid a ReferenceError when
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// accessing subscription below in the closure due to Temporal Dead Zone.
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let subscription: Subscription;
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subscription = this.subscribe((value) => {
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try {
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next(value);
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} catch (err) {
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reject(err);
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if (subscription) {
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subscription.unsubscribe();
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}
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}
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}, reject, resolve);
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}) as Promise<void>;
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}
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/** @internal This is an internal implementation detail, do not use. */
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_subscribe(subscriber: Subscriber<any>): TeardownLogic {
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const { source } = this;
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return source && source.subscribe(subscriber);
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}
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// `if` and `throw` are special snow flakes, the compiler sees them as reserved words. Deprecated in
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// favor of iif and throwError functions.
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/**
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* @nocollapse
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* @deprecated In favor of iif creation function: import { iif } from 'rxjs';
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*/
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static if: typeof iif;
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/**
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* @nocollapse
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* @deprecated In favor of throwError creation function: import { throwError } from 'rxjs';
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*/
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static throw: typeof throwError;
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/**
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* An interop point defined by the es7-observable spec https://github.com/zenparsing/es-observable
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* @method Symbol.observable
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* @return {Observable} this instance of the observable
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*/
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[Symbol_observable]() {
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return this;
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}
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/* tslint:disable:max-line-length */
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pipe(): Observable<T>;
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pipe<A>(op1: OperatorFunction<T, A>): Observable<A>;
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pipe<A, B>(op1: OperatorFunction<T, A>, op2: OperatorFunction<A, B>): Observable<B>;
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pipe<A, B, C>(op1: OperatorFunction<T, A>, op2: OperatorFunction<A, B>, op3: OperatorFunction<B, C>): Observable<C>;
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pipe<A, B, C, D>(op1: OperatorFunction<T, A>, op2: OperatorFunction<A, B>, op3: OperatorFunction<B, C>, op4: OperatorFunction<C, D>): Observable<D>;
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pipe<A, B, C, D, E>(op1: OperatorFunction<T, A>, op2: OperatorFunction<A, B>, op3: OperatorFunction<B, C>, op4: OperatorFunction<C, D>, op5: OperatorFunction<D, E>): Observable<E>;
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pipe<A, B, C, D, E, F>(op1: OperatorFunction<T, A>, op2: OperatorFunction<A, B>, op3: OperatorFunction<B, C>, op4: OperatorFunction<C, D>, op5: OperatorFunction<D, E>, op6: OperatorFunction<E, F>): Observable<F>;
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pipe<A, B, C, D, E, F, G>(op1: OperatorFunction<T, A>, op2: OperatorFunction<A, B>, op3: OperatorFunction<B, C>, op4: OperatorFunction<C, D>, op5: OperatorFunction<D, E>, op6: OperatorFunction<E, F>, op7: OperatorFunction<F, G>): Observable<G>;
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pipe<A, B, C, D, E, F, G, H>(op1: OperatorFunction<T, A>, op2: OperatorFunction<A, B>, op3: OperatorFunction<B, C>, op4: OperatorFunction<C, D>, op5: OperatorFunction<D, E>, op6: OperatorFunction<E, F>, op7: OperatorFunction<F, G>, op8: OperatorFunction<G, H>): Observable<H>;
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pipe<A, B, C, D, E, F, G, H, I>(op1: OperatorFunction<T, A>, op2: OperatorFunction<A, B>, op3: OperatorFunction<B, C>, op4: OperatorFunction<C, D>, op5: OperatorFunction<D, E>, op6: OperatorFunction<E, F>, op7: OperatorFunction<F, G>, op8: OperatorFunction<G, H>, op9: OperatorFunction<H, I>): Observable<I>;
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pipe<A, B, C, D, E, F, G, H, I>(op1: OperatorFunction<T, A>, op2: OperatorFunction<A, B>, op3: OperatorFunction<B, C>, op4: OperatorFunction<C, D>, op5: OperatorFunction<D, E>, op6: OperatorFunction<E, F>, op7: OperatorFunction<F, G>, op8: OperatorFunction<G, H>, op9: OperatorFunction<H, I>, ...operations: OperatorFunction<any, any>[]): Observable<{}>;
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/* tslint:enable:max-line-length */
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/**
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* Used to stitch together functional operators into a chain.
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* @method pipe
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* @return {Observable} the Observable result of all of the operators having
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* been called in the order they were passed in.
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*
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* ### Example
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* ```ts
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* import { interval } from 'rxjs';
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* import { map, filter, scan } from 'rxjs/operators';
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*
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* interval(1000)
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* .pipe(
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* filter(x => x % 2 === 0),
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* map(x => x + x),
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* scan((acc, x) => acc + x)
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* )
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* .subscribe(x => console.log(x))
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* ```
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*/
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pipe(...operations: OperatorFunction<any, any>[]): Observable<any> {
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if (operations.length === 0) {
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return this as any;
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}
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return pipeFromArray(operations)(this);
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}
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/* tslint:disable:max-line-length */
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toPromise<T>(this: Observable<T>): Promise<T>;
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toPromise<T>(this: Observable<T>, PromiseCtor: typeof Promise): Promise<T>;
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toPromise<T>(this: Observable<T>, PromiseCtor: PromiseConstructorLike): Promise<T>;
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/* tslint:enable:max-line-length */
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toPromise(promiseCtor?: PromiseConstructorLike): Promise<T> {
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promiseCtor = getPromiseCtor(promiseCtor);
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return new promiseCtor((resolve, reject) => {
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let value: any;
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this.subscribe((x: T) => value = x, (err: any) => reject(err), () => resolve(value));
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}) as Promise<T>;
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}
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}
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/**
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* Decides between a passed promise constructor from consuming code,
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* A default configured promise constructor, and the native promise
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* constructor and returns it. If nothing can be found, it will throw
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* an error.
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* @param promiseCtor The optional promise constructor to passed by consuming code
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*/
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function getPromiseCtor(promiseCtor: PromiseConstructorLike | undefined) {
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if (!promiseCtor) {
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promiseCtor = config.Promise || Promise;
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}
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if (!promiseCtor) {
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throw new Error('no Promise impl found');
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}
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return promiseCtor;
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}
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