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event_emitter.ts
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191 lines (171 loc) Β· 5.51 KB
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/**
* @license
* Copyright Google LLC All Rights Reserved.
*
* Use of this source code is governed by an MIT-style license that can be
* found in the LICENSE file at https://angular.dev/license
*/
import {setActiveConsumer} from '@angular/core/primitives/signals';
import {PartialObserver, Subject, Subscription} from 'rxjs';
import {OutputRef} from './authoring/output/output_ref';
import {isInInjectionContext} from './di/contextual';
import {inject} from './di/injector_compatibility';
import {DestroyRef} from './linker/destroy_ref';
import {PendingTasksInternal} from './pending_tasks';
/**
* Use in components with the `@Output` directive to emit custom events
* synchronously or asynchronously, and register handlers for those events
* by subscribing to an instance.
*
* @usageNotes
*
* Extends
* [RxJS `Subject`](https://rxjs.dev/api/index/class/Subject)
* for Angular by adding the `emit()` method.
*
* In the following example, a component defines two output properties
* that create event emitters. When the title is clicked, the emitter
* emits an open or close event to toggle the current visibility state.
*
* ```html
* @Component({
* selector: 'zippy',
* template: `
* <div class="zippy">
* <div (click)="toggle()">Toggle</div>
* <div [hidden]="!visible">
* <ng-content></ng-content>
* </div>
* </div>`})
* export class Zippy {
* visible: boolean = true;
* @Output() open: EventEmitter<any> = new EventEmitter();
* @Output() close: EventEmitter<any> = new EventEmitter();
*
* toggle() {
* this.visible = !this.visible;
* if (this.visible) {
* this.open.emit(null);
* } else {
* this.close.emit(null);
* }
* }
* }
* ```
*
* Access the event object with the `$event` argument passed to the output event
* handler:
*
* ```html
* <zippy (open)="onOpen($event)" (close)="onClose($event)"></zippy>
* ```
*
* @publicApi
*/
export interface EventEmitter<T> extends Subject<T>, OutputRef<T> {
/**
* @internal
*/
__isAsync: boolean;
/**
* Creates an instance of this class that can
* deliver events synchronously or asynchronously.
*
* @param [isAsync=false] When true, deliver events asynchronously.
*
*/
new (isAsync?: boolean): EventEmitter<T>;
/**
* Emits an event containing a given value.
* @param value The value to emit.
*/
emit(value?: T): void;
/**
* Registers handlers for events emitted by this instance.
* @param next When supplied, a custom handler for emitted events.
* @param error When supplied, a custom handler for an error notification from this emitter.
* @param complete When supplied, a custom handler for a completion notification from this
* emitter.
*/
subscribe(
next?: (value: T) => void,
error?: (error: any) => void,
complete?: () => void,
): Subscription;
/**
* Registers handlers for events emitted by this instance.
* @param observerOrNext When supplied, a custom handler for emitted events, or an observer
* object.
* @param error When supplied, a custom handler for an error notification from this emitter.
* @param complete When supplied, a custom handler for a completion notification from this
* emitter.
*/
subscribe(observerOrNext?: any, error?: any, complete?: any): Subscription;
}
class EventEmitter_ extends Subject<any> implements OutputRef<any> {
__isAsync: boolean; // tslint:disable-line
destroyRef: DestroyRef | undefined = undefined;
private readonly pendingTasks: PendingTasksInternal | undefined = undefined;
constructor(isAsync: boolean = false) {
super();
this.__isAsync = isAsync;
// Attempt to retrieve a `DestroyRef` and `PendingTasks` optionally.
// For backwards compatibility reasons, this cannot be required.
if (isInInjectionContext()) {
this.destroyRef = inject(DestroyRef, {optional: true}) ?? undefined;
this.pendingTasks = inject(PendingTasksInternal, {optional: true}) ?? undefined;
}
}
emit(value?: any) {
const prevConsumer = setActiveConsumer(null);
try {
super.next(value);
} finally {
setActiveConsumer(prevConsumer);
}
}
override subscribe(observerOrNext?: any, error?: any, complete?: any): Subscription {
let nextFn = observerOrNext;
let errorFn = error || (() => null);
let completeFn = complete;
if (observerOrNext && typeof observerOrNext === 'object') {
const observer = observerOrNext as PartialObserver<unknown>;
nextFn = observer.next?.bind(observer);
errorFn = observer.error?.bind(observer);
completeFn = observer.complete?.bind(observer);
}
if (this.__isAsync) {
errorFn = this.wrapInTimeout(errorFn);
if (nextFn) {
nextFn = this.wrapInTimeout(nextFn);
}
if (completeFn) {
completeFn = this.wrapInTimeout(completeFn);
}
}
const sink = super.subscribe({next: nextFn, error: errorFn, complete: completeFn});
if (observerOrNext instanceof Subscription) {
observerOrNext.add(sink);
}
return sink;
}
private wrapInTimeout(fn: (value: unknown) => any) {
return (value: unknown) => {
const taskId = this.pendingTasks?.add();
setTimeout(() => {
fn(value);
if (taskId !== undefined) {
this.pendingTasks?.remove(taskId);
}
});
};
}
}
/**
* @publicApi
*/
export const EventEmitter: {
new (isAsync?: boolean): EventEmitter<any>;
new <T>(isAsync?: boolean): EventEmitter<T>;
readonly prototype: EventEmitter<any>;
} = EventEmitter_ as any;