es6/observable/PromiseObservable.js

import { root } from '../util/root';
import { Observable } from '../Observable';
/**
 * We need this JSDoc comment for affecting ESDoc.
 * @extends {Ignored}
 * @hide true
 */
export class PromiseObservable extends Observable {
    constructor(promise, scheduler) {
        super();
        this.promise = promise;
        this.scheduler = scheduler;
    }
    /**
     * 将 Promise 转化为 Observable。
     *
     * <span class="informal">返回一个仅仅发出 Promise resolve 过的值然后完成的 Observable。</span>
     *
     * 把 ES2015 的 Promise 或者兼容 Promises/A+ 规范的 Promise 转化为 Observable。 如果 Promise resolves
     * 一个值, 输出 Observable 发出这个值然后完成。 如果 Promise 被 rejected, 输出 Observable 会发出相应的
     * 错误。
     *
     * @example <caption>将 Fetch 返回的 Promise 转化为 Observable。</caption>
     * var result = Rx.Observable.fromPromise(fetch('http://myserver.com/'));
     * result.subscribe(x => console.log(x), e => console.error(e));
     *
     * @see {@link bindCallback}
     * @see {@link from}
     *
     * @param {PromiseLike<T>} promise 被转化的 promise。
     * @param {Scheduler} [scheduler] 可选的调度器，用来调度 resolved 或者 rejection 的值。
     * @return {Observable<T>} 包装了 Promise 的 Observable。
     * @static true
     * @name fromPromise
     * @owner Observable
     */
    static create(promise, scheduler) {
        return new PromiseObservable(promise, scheduler);
    }
    _subscribe(subscriber) {
        const promise = this.promise;
        const scheduler = this.scheduler;
        if (scheduler == null) {
            if (this._isScalar) {
                if (!subscriber.closed) {
                    subscriber.next(this.value);
                    subscriber.complete();
                }
            }
            else {
                promise.then((value) => {
                    this.value = value;
                    this._isScalar = true;
                    if (!subscriber.closed) {
                        subscriber.next(value);
                        subscriber.complete();
                    }
                }, (err) => {
                    if (!subscriber.closed) {
                        subscriber.error(err);
                    }
                })
                    .then(null, err => {
                    // escape the promise trap, throw unhandled errors
                    root.setTimeout(() => { throw err; });
                });
            }
        }
        else {
            if (this._isScalar) {
                if (!subscriber.closed) {
                    return scheduler.schedule(dispatchNext, 0, { value: this.value, subscriber });
                }
            }
            else {
                promise.then((value) => {
                    this.value = value;
                    this._isScalar = true;
                    if (!subscriber.closed) {
                        subscriber.add(scheduler.schedule(dispatchNext, 0, { value, subscriber }));
                    }
                }, (err) => {
                    if (!subscriber.closed) {
                        subscriber.add(scheduler.schedule(dispatchError, 0, { err, subscriber }));
                    }
                })
                    .then(null, (err) => {
                    // escape the promise trap, throw unhandled errors
                    root.setTimeout(() => { throw err; });
                });
            }
        }
    }
}
function dispatchNext(arg) {
    const { value, subscriber } = arg;
    if (!subscriber.closed) {
        subscriber.next(value);
        subscriber.complete();
    }
}
function dispatchError(arg) {
    const { err, subscriber } = arg;
    if (!subscriber.closed) {
        subscriber.error(err);
    }
}
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