import { ReactiveController, ReactiveControllerHost } from "lit";
/** Encapsulates options used to monitor the state of one or more elements. */
export interface MonitorControllerOptions {
    /**
     * The element to observe. In addition to configuring the target here,
     * the `observe` method can be called to observe additional targets. When
     * not specified, the target defaults to the `host`. If set to `null`, no
     * target is automatically observed. Only the configured target will be
     * re-observed if the host connects again after unobserving via disconnection.
     */
    target?: HTMLElement | null;
}
/**
 * A base implementation for a `ReactiveController` used to monitor the state of one
 * or more elements. This class must be inherited.
 */
export declare abstract class MonitorControllerBase implements ReactiveController {
    #private;
    /**
     * Initializes the `MonitorControllerBase` base class values when called by a derived class.
     * @param {ReactiveControllerHost & HTMLElement} host The host element to which this controller will be added.
     * @param {MonitorControllerOptions} options Options used to configure this controller.
     */
    constructor(host: ReactiveControllerHost & HTMLElement, options: MonitorControllerOptions);
    /** The targets being observed. */
    get targets(): Iterable<HTMLElement>;
    /** @inheritdoc */
    hostConnected(): void;
    /** @inheritdoc */
    hostDisconnected(): void;
    /** @inheritdoc */
    hostUpdate?(): void;
    /** @inheritdoc */
    hostUpdated?(): void;
    /**
     * Starts observing the specified element.
     * @param {HTMLElement} target The element to start observing.
     */
    observe(target: HTMLElement): void;
    /**
     * Determines whether the specified element is being observed.
     * @param {HTMLElement} target The element to test.
     * @returns {boolean} Whether `target` is being observed.
     */
    isObserving(target: HTMLElement): boolean;
    /**
     * Stops observing the specified element.
     * @param {HTMLElement} target The element to stop observing.
     */
    unobserve(target: HTMLElement): void;
    /**
     * When implemented by a derived class, starts observing the specified element.
     * @param {HTMLElement} target The element to start observing.
     */
    protected abstract _observe(target: HTMLElement): void;
    /**
     * When implemented by a derived class, stops observing the specified element.
     * @param {HTMLElement} target The element to stop observing.
     */
    protected abstract _unobserve(target: HTMLElement): void;
}
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