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