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- import { isArrayLike } from '../util/isArrayLike';
- import { isPromise } from '../util/isPromise';
- import { Observable } from '../Observable';
- import { ObservableInput, ObservedValueOf, ReadableStreamLike } from '../types';
- import { isInteropObservable } from '../util/isInteropObservable';
- import { isAsyncIterable } from '../util/isAsyncIterable';
- import { createInvalidObservableTypeError } from '../util/throwUnobservableError';
- import { isIterable } from '../util/isIterable';
- import { isReadableStreamLike, readableStreamLikeToAsyncGenerator } from '../util/isReadableStreamLike';
- import { Subscriber } from '../Subscriber';
- import { isFunction } from '../util/isFunction';
- import { reportUnhandledError } from '../util/reportUnhandledError';
- import { observable as Symbol_observable } from '../symbol/observable';
- export function innerFrom<O extends ObservableInput<any>>(input: O): Observable<ObservedValueOf<O>>;
- export function innerFrom<T>(input: ObservableInput<T>): Observable<T> {
- if (input instanceof Observable) {
- return input;
- }
- if (input != null) {
- if (isInteropObservable(input)) {
- return fromInteropObservable(input);
- }
- if (isArrayLike(input)) {
- return fromArrayLike(input);
- }
- if (isPromise(input)) {
- return fromPromise(input);
- }
- if (isAsyncIterable(input)) {
- return fromAsyncIterable(input);
- }
- if (isIterable(input)) {
- return fromIterable(input);
- }
- if (isReadableStreamLike(input)) {
- return fromReadableStreamLike(input);
- }
- }
- throw createInvalidObservableTypeError(input);
- }
- /**
- * Creates an RxJS Observable from an object that implements `Symbol.observable`.
- * @param obj An object that properly implements `Symbol.observable`.
- */
- export function fromInteropObservable<T>(obj: any) {
- return new Observable((subscriber: Subscriber<T>) => {
- const obs = obj[Symbol_observable]();
- if (isFunction(obs.subscribe)) {
- return obs.subscribe(subscriber);
- }
- // Should be caught by observable subscribe function error handling.
- throw new TypeError('Provided object does not correctly implement Symbol.observable');
- });
- }
- /**
- * Synchronously emits the values of an array like and completes.
- * This is exported because there are creation functions and operators that need to
- * make direct use of the same logic, and there's no reason to make them run through
- * `from` conditionals because we *know* they're dealing with an array.
- * @param array The array to emit values from
- */
- export function fromArrayLike<T>(array: ArrayLike<T>) {
- return new Observable((subscriber: Subscriber<T>) => {
- // Loop over the array and emit each value. Note two things here:
- // 1. We're making sure that the subscriber is not closed on each loop.
- // This is so we don't continue looping over a very large array after
- // something like a `take`, `takeWhile`, or other synchronous unsubscription
- // has already unsubscribed.
- // 2. In this form, reentrant code can alter that array we're looping over.
- // This is a known issue, but considered an edge case. The alternative would
- // be to copy the array before executing the loop, but this has
- // performance implications.
- for (let i = 0; i < array.length && !subscriber.closed; i++) {
- subscriber.next(array[i]);
- }
- subscriber.complete();
- });
- }
- export function fromPromise<T>(promise: PromiseLike<T>) {
- return new Observable((subscriber: Subscriber<T>) => {
- promise
- .then(
- (value) => {
- if (!subscriber.closed) {
- subscriber.next(value);
- subscriber.complete();
- }
- },
- (err: any) => subscriber.error(err)
- )
- .then(null, reportUnhandledError);
- });
- }
- export function fromIterable<T>(iterable: Iterable<T>) {
- return new Observable((subscriber: Subscriber<T>) => {
- for (const value of iterable) {
- subscriber.next(value);
- if (subscriber.closed) {
- return;
- }
- }
- subscriber.complete();
- });
- }
- export function fromAsyncIterable<T>(asyncIterable: AsyncIterable<T>) {
- return new Observable((subscriber: Subscriber<T>) => {
- process(asyncIterable, subscriber).catch((err) => subscriber.error(err));
- });
- }
- export function fromReadableStreamLike<T>(readableStream: ReadableStreamLike<T>) {
- return fromAsyncIterable(readableStreamLikeToAsyncGenerator(readableStream));
- }
- async function process<T>(asyncIterable: AsyncIterable<T>, subscriber: Subscriber<T>) {
- for await (const value of asyncIterable) {
- subscriber.next(value);
- // A side-effect may have closed our subscriber,
- // check before the next iteration.
- if (subscriber.closed) {
- return;
- }
- }
- subscriber.complete();
- }
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