/**
 * @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 { Subject, Subscription } from 'rxjs';
import { OutputRef } from './authoring/output/output_ref';
/**
 * 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.
 *
 * ```angular-ts
 * @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>
 * ```
 *
 * @see [Declaring outputs with the @Output decorator](guide/components/outputs#declaring-outputs-with-the-output-decorator)
 *
 * @publicApi
 */
export interface EventEmitter<T> extends Subject<T>, OutputRef<T> {
    /**
     * 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;
}
/**
 * @publicApi
 */
export declare const EventEmitter: {
    new (isAsync?: boolean): EventEmitter<any>;
    new <T>(isAsync?: boolean): EventEmitter<T>;
    readonly prototype: EventEmitter<any>;
};