import { ReactiveController, ReactiveElement } from 'lit';
export interface SlotAttributePropagationControllerOptions {
    /** The attribute name to propagate to assigned elements. */
    attribute: string;
    /**
     * Returns the current value to propagate. Return `null` to remove the
     * attribute from assigned elements, for attributes that are only
     * sometimes present on the host.
     */
    getValue: () => string | null;
    /** Named slot to target. Omit for the default (unnamed) slot. */
    slotName?: string;
    /**
     * CSS selector used to filter assigned elements before propagating.
     * Omit to propagate to all assigned elements.
     */
    selector?: string;
}
/**
 * A Lit {@link ReactiveController} that propagates an attribute from the host
 * element to elements assigned to one of its slots.
 *
 * The controller automatically re-propagates in `hostUpdated()` whenever the
 * value returned by `getValue` changes. Call `propagate()` from the host's
 * `slotchange` handler to cover elements inserted after the first render.
 *
 * `getValue` may return `null` for attributes that are only sometimes present
 * on the host; the controller removes the attribute from assigned elements
 * rather than setting it to an empty string.
 *
 * @example
 * ```ts
 * class MyBase extends SpectrumElement {
 *   @property({ type: String, reflect: true })
 *   public size: MySize = 'm';
 *
 *   private readonly _sizePropagation = new SlotAttributePropagationController(this, {
 *     attribute: 'size',
 *     getValue: () => this.size,
 *     slotName: 'actions',
 *   });
 *
 *   protected handleActionsSlotChange(): void {
 *     this._sizePropagation.propagate();
 *   }
 * }
 * ```
 */
export declare class SlotAttributePropagationController implements ReactiveController {
    private readonly _host;
    private readonly _options;
    private _previousValue?;
    constructor(host: ReactiveElement, options: SlotAttributePropagationControllerOptions);
    hostDisconnected(): void;
    hostUpdated(): void;
    /**
     * Propagates the current value to all matching assigned elements
     * immediately, updating the value tracked for the `hostUpdated()` no-op
     * guard so it isn't repeated once the pending update runs. Call this from
     * the host's `slotchange` event handler.
     */
    propagate(): void;
    private _propagateToSlot;
    private _resolveSlot;
}