import { Observable, PartialObserver, Subject, Subscription } from 'rxjs';
import { OnDestroy } from '@angular/core';
import * as i0 from "@angular/core";
/**
 * Facilitates working with components, directives and services which manually subscribe to observables.
 * Extend this class to easily hook into ngOnDestroy and avoid memory leaks.
 *
 * @see [Wiki](https://bs-angular-zen.web.app/docs/zen/additional-documentation/coremodule/destroyable-(abstract).html) for full guide.
 *
 * @export
 * @abstract
 * @class Destroyable
 * @implements {OnDestroy}
 */
export declare abstract class Destroyable implements OnDestroy {
    /**
     * Emits a value when `ngOnDestroy()` is called.
     * Pipe together with `takeUntil()` to auto unsubscribe from your observables.
     *
     * @example
     * observable.pipe(takeUntil(this.destroyed)).subscribe(...);
     *
     * @protected
     * @type {Subject<void>}
     */
    protected readonly destroyed: Subject<void>;
    /**
     * A list of all subscriptions manually added using the `subscribe()` method.
     * These are automatically unsubscribed when `ngOnDestroy()` is called.
     *
     * @protected
     * @type {Subscription}
     */
    protected readonly subscriptions: Subscription;
    ngOnDestroy(): void;
    /**
     * Subscribes to an observable and stores the subscription for automatic disposal.
     * When `ngOnDestroy()` is called, all subscriptions created with this method will unsubscribe.
     *
     * @protected
     * @template T The type of data the observable will emit.
     * @param {Observable<T>} observable The observable to subscribe to.
     * @param {(value: T) => void} [next] (Optional) A callback function to execute on each emission of the observable.
     * @param {(error: any) => void} [error] (Optional) A callback function to execute when the observable errors.
     * @param {() => void} [complete] (Optional) A callback function to execute when the observable completes.
     * @returns {Subscription} The subscription created for the observable.
     */
    protected subscribe<T>(observable: Observable<T>, next?: (value: T) => void, error?: (error: unknown) => void, complete?: () => void): Subscription;
    /**
     * Subscribes to an observable and stores the subscription for automatic disposal.
     * When `ngOnDestroy()` is called, all subscriptions created with this method will unsubscribe.
     *
     * @protected
     * @template T The type of data the observable will emit.
     * @param {Observable<T>} observable The observable to subscribe to.
     * @param {PartialObserver<T>} [observer] The observer that will handle observable events.
     * @returns {Subscription} The subscription created for the observable.
     */
    protected subscribe<T>(observable: Observable<T>, observer?: PartialObserver<T>): Subscription;
    static ɵfac: i0.ɵɵFactoryDeclaration<Destroyable, never>;
    static ɵdir: i0.ɵɵDirectiveDeclaration<Destroyable, never, never, {}, {}, never, never, false>;
}