| import { root } from './util/root'; |
| import { toSubscriber } from './util/toSubscriber'; |
| import { observable as Symbol_observable } from './symbol/observable'; |
| import { pipeFromArray } from './util/pipe'; |
| /** |
| * 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 { |
| /** |
| * @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._isScalar = false; |
| if (subscribe) { |
| this._subscribe = 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(operator) { |
| const observable = new Observable(); |
| observable.source = this; |
| observable.operator = operator; |
| return observable; |
| } |
| /** |
| * 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 a {@link create} static factory, but most of the time it is |
| * a library implementation, which defines what and when will be emitted by an Observable. This means that calling |
| * `subscribe` is actually the moment when Observable starts its work, not when it is created, as it is often |
| * 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 |
| * 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, that if `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 first function is equivalent |
| * of a `next` method, second of an `error` method and 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. |
| * |
| * Whatever 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 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 {@link Scheduler}. |
| * |
| * @example <caption>Subscribe with an Observer</caption> |
| * 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); |
| * } |
| * }; |
| * |
| * Rx.Observable.of(1, 2, 3) // Synchronously emits 1, 2, 3 and then completes. |
| * .subscribe(sumObserver); |
| * |
| * // Logs: |
| * // "Adding: 1" |
| * // "Adding: 2" |
| * // "Adding: 3" |
| * // "Sum equals: 6" |
| * |
| * |
| * @example <caption>Subscribe with functions</caption> |
| * let sum = 0; |
| * |
| * Rx.Observable.of(1, 2, 3) |
| * .subscribe( |
| * function(value) { |
| * console.log('Adding: ' + value); |
| * sum = sum + value; |
| * }, |
| * undefined, |
| * function() { |
| * console.log('Sum equals: ' + sum); |
| * } |
| * ); |
| * |
| * // Logs: |
| * // "Adding: 1" |
| * // "Adding: 2" |
| * // "Adding: 3" |
| * // "Sum equals: 6" |
| * |
| * |
| * @example <caption>Cancel a subscription</caption> |
| * const subscription = Rx.Observable.interval(1000).subscribe( |
| * num => console.log(num), |
| * undefined, |
| * () => console.log('completed!') // Will not be called, even |
| * ); // when cancelling subscription |
| * |
| * |
| * 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, error, complete) { |
| const { operator } = this; |
| const sink = toSubscriber(observerOrNext, error, complete); |
| if (operator) { |
| operator.call(sink, this.source); |
| } |
| else { |
| sink.add(this.source || !sink.syncErrorThrowable ? this._subscribe(sink) : this._trySubscribe(sink)); |
| } |
| if (sink.syncErrorThrowable) { |
| sink.syncErrorThrowable = false; |
| if (sink.syncErrorThrown) { |
| throw sink.syncErrorValue; |
| } |
| } |
| return sink; |
| } |
| _trySubscribe(sink) { |
| try { |
| return this._subscribe(sink); |
| } |
| catch (err) { |
| sink.syncErrorThrown = true; |
| sink.syncErrorValue = err; |
| sink.error(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, PromiseCtor) { |
| if (!PromiseCtor) { |
| if (root.Rx && root.Rx.config && root.Rx.config.Promise) { |
| PromiseCtor = root.Rx.config.Promise; |
| } |
| else if (root.Promise) { |
| PromiseCtor = root.Promise; |
| } |
| } |
| if (!PromiseCtor) { |
| throw new Error('no Promise impl found'); |
| } |
| return new PromiseCtor((resolve, reject) => { |
| // Must be declared in a separate statement to avoid a RefernceError when |
| // accessing subscription below in the closure due to Temporal Dead Zone. |
| let subscription; |
| subscription = this.subscribe((value) => { |
| if (subscription) { |
| // if there is a subscription, then we can surmise |
| // the next handling is asynchronous. Any errors thrown |
| // need to be rejected explicitly and unsubscribe must be |
| // called manually |
| try { |
| next(value); |
| } |
| catch (err) { |
| reject(err); |
| subscription.unsubscribe(); |
| } |
| } |
| else { |
| // if there is NO subscription, then we're getting a nexted |
| // value synchronously during subscription. We can just call it. |
| // If it errors, Observable's `subscribe` will ensure the |
| // unsubscription logic is called, then synchronously rethrow the error. |
| // After that, Promise will trap the error and send it |
| // down the rejection path. |
| next(value); |
| } |
| }, reject, resolve); |
| }); |
| } |
| _subscribe(subscriber) { |
| return this.source.subscribe(subscriber); |
| } |
| /** |
| * 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: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 |
| * |
| * import { map, filter, scan } from 'rxjs/operators'; |
| * |
| * Rx.Observable.interval(1000) |
| * .pipe( |
| * filter(x => x % 2 === 0), |
| * map(x => x + x), |
| * scan((acc, x) => acc + x) |
| * ) |
| * .subscribe(x => console.log(x)) |
| */ |
| pipe(...operations) { |
| if (operations.length === 0) { |
| return this; |
| } |
| return pipeFromArray(operations)(this); |
| } |
| /* tslint:enable:max-line-length */ |
| toPromise(PromiseCtor) { |
| if (!PromiseCtor) { |
| if (root.Rx && root.Rx.config && root.Rx.config.Promise) { |
| PromiseCtor = root.Rx.config.Promise; |
| } |
| else if (root.Promise) { |
| PromiseCtor = root.Promise; |
| } |
| } |
| if (!PromiseCtor) { |
| throw new Error('no Promise impl found'); |
| } |
| return new PromiseCtor((resolve, reject) => { |
| let value; |
| this.subscribe((x) => value = x, (err) => reject(err), () => resolve(value)); |
| }); |
| } |
| } |
| // 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 |
| */ |
| Observable.create = (subscribe) => { |
| return new Observable(subscribe); |
| }; |
| //# sourceMappingURL=Observable.js.map |
