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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();
}