190 lines
7.4 KiB
JavaScript
190 lines
7.4 KiB
JavaScript
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import { isArray } from './util/isArray';
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import { isObject } from './util/isObject';
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import { isFunction } from './util/isFunction';
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import { tryCatch } from './util/tryCatch';
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import { errorObject } from './util/errorObject';
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import { UnsubscriptionError } from './util/UnsubscriptionError';
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/**
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* Represents a disposable resource, such as the execution of an Observable. A
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* Subscription has one important method, `unsubscribe`, that takes no argument
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* and just disposes the resource held by the subscription.
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*
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* Additionally, subscriptions may be grouped together through the `add()`
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* method, which will attach a child Subscription to the current Subscription.
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* When a Subscription is unsubscribed, all its children (and its grandchildren)
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* will be unsubscribed as well.
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*
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* @class Subscription
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*/
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export class Subscription {
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/**
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* @param {function(): void} [unsubscribe] A function describing how to
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* perform the disposal of resources when the `unsubscribe` method is called.
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*/
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constructor(unsubscribe) {
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/**
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* A flag to indicate whether this Subscription has already been unsubscribed.
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* @type {boolean}
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*/
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this.closed = false;
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this._parent = null;
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this._parents = null;
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this._subscriptions = null;
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if (unsubscribe) {
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this._unsubscribe = unsubscribe;
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}
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}
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/**
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* Disposes the resources held by the subscription. May, for instance, cancel
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* an ongoing Observable execution or cancel any other type of work that
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* started when the Subscription was created.
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* @return {void}
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*/
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unsubscribe() {
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let hasErrors = false;
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let errors;
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if (this.closed) {
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return;
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}
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let { _parent, _parents, _unsubscribe, _subscriptions } = this;
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this.closed = true;
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this._parent = null;
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this._parents = null;
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// null out _subscriptions first so any child subscriptions that attempt
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// to remove themselves from this subscription will noop
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this._subscriptions = null;
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let index = -1;
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let len = _parents ? _parents.length : 0;
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// if this._parent is null, then so is this._parents, and we
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// don't have to remove ourselves from any parent subscriptions.
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while (_parent) {
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_parent.remove(this);
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// if this._parents is null or index >= len,
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// then _parent is set to null, and the loop exits
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_parent = ++index < len && _parents[index] || null;
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}
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if (isFunction(_unsubscribe)) {
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let trial = tryCatch(_unsubscribe).call(this);
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if (trial === errorObject) {
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hasErrors = true;
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errors = errors || (errorObject.e instanceof UnsubscriptionError ?
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flattenUnsubscriptionErrors(errorObject.e.errors) : [errorObject.e]);
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}
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}
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if (isArray(_subscriptions)) {
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index = -1;
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len = _subscriptions.length;
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while (++index < len) {
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const sub = _subscriptions[index];
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if (isObject(sub)) {
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let trial = tryCatch(sub.unsubscribe).call(sub);
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if (trial === errorObject) {
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hasErrors = true;
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errors = errors || [];
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let err = errorObject.e;
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if (err instanceof UnsubscriptionError) {
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errors = errors.concat(flattenUnsubscriptionErrors(err.errors));
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}
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else {
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errors.push(err);
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}
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}
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}
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}
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}
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if (hasErrors) {
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throw new UnsubscriptionError(errors);
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}
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}
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/**
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* Adds a tear down to be called during the unsubscribe() of this
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* Subscription.
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*
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* If the tear down being added is a subscription that is already
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* unsubscribed, is the same reference `add` is being called on, or is
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* `Subscription.EMPTY`, it will not be added.
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*
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* If this subscription is already in an `closed` state, the passed
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* tear down logic will be executed immediately.
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*
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* @param {TeardownLogic} teardown The additional logic to execute on
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* teardown.
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* @return {Subscription} Returns the Subscription used or created to be
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* added to the inner subscriptions list. This Subscription can be used with
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* `remove()` to remove the passed teardown logic from the inner subscriptions
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* list.
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*/
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add(teardown) {
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if (!teardown || (teardown === Subscription.EMPTY)) {
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return Subscription.EMPTY;
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}
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if (teardown === this) {
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return this;
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}
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let subscription = teardown;
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switch (typeof teardown) {
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case 'function':
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subscription = new Subscription(teardown);
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case 'object':
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if (subscription.closed || typeof subscription.unsubscribe !== 'function') {
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return subscription;
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}
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else if (this.closed) {
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subscription.unsubscribe();
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return subscription;
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}
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else if (typeof subscription._addParent !== 'function' /* quack quack */) {
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const tmp = subscription;
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subscription = new Subscription();
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subscription._subscriptions = [tmp];
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}
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break;
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default:
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throw new Error('unrecognized teardown ' + teardown + ' added to Subscription.');
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}
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const subscriptions = this._subscriptions || (this._subscriptions = []);
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subscriptions.push(subscription);
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subscription._addParent(this);
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return subscription;
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}
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/**
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* Removes a Subscription from the internal list of subscriptions that will
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* unsubscribe during the unsubscribe process of this Subscription.
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* @param {Subscription} subscription The subscription to remove.
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* @return {void}
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*/
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remove(subscription) {
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const subscriptions = this._subscriptions;
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if (subscriptions) {
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const subscriptionIndex = subscriptions.indexOf(subscription);
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if (subscriptionIndex !== -1) {
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subscriptions.splice(subscriptionIndex, 1);
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}
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}
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}
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_addParent(parent) {
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let { _parent, _parents } = this;
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if (!_parent || _parent === parent) {
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// If we don't have a parent, or the new parent is the same as the
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// current parent, then set this._parent to the new parent.
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this._parent = parent;
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}
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else if (!_parents) {
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// If there's already one parent, but not multiple, allocate an Array to
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// store the rest of the parent Subscriptions.
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this._parents = [parent];
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}
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else if (_parents.indexOf(parent) === -1) {
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// Only add the new parent to the _parents list if it's not already there.
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_parents.push(parent);
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}
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}
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}
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Subscription.EMPTY = (function (empty) {
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empty.closed = true;
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return empty;
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}(new Subscription()));
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function flattenUnsubscriptionErrors(errors) {
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return errors.reduce((errs, err) => errs.concat((err instanceof UnsubscriptionError) ? err.errors : err), []);
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}
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//# sourceMappingURL=Subscription.js.map
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