import type { ReactiveController, ReactiveControllerHost } from 'lit';
/**
 * Keeps an element in sync with the light-DOM `<datalist>` it reads its options
 * from (`l-select`, `l-combobox`).
 *
 * Those elements cache the options in a `_items` array rather than re-reading
 * the DOM on every render, so the cache needs invalidating — and nothing else
 * can do it. The `<datalist>` is never slotted (it is read, not projected), so
 * there is no `slotchange` to listen for, and a consumer that re-labels an
 * option in place — a localized language picker, or any framework re-render,
 * since Vue/React/Svelte all patch the existing `<option>` nodes instead of
 * replacing them — triggers no reconnection either. Without this, the
 * always-visible surface (the closed trigger, the input) goes on showing the
 * previous label until something happens to re-read the list. The native tier
 * (`<select class="l-select">`) reflects the edit immediately; this makes the
 * custom tier match.
 *
 * Two observers, because the host is the wrong thing to watch for options: it
 * reflects its own `value` / `disabled` attributes, so watching it for
 * attributes means the element wakes its own observer on every selection. The
 * options are watched on the `<datalist>` itself; the host is watched for
 * children alone, which is what notices the list being inserted or swapped.
 *
 * ```ts
 * private _options = new DatalistObserverController(this, () => this._syncItems());
 * ```
 */
export declare class DatalistObserverController implements ReactiveController {
    private host;
    private onChange;
    private hostObserver?;
    private listObserver?;
    private list;
    constructor(host: ReactiveControllerHost & HTMLElement, onChange: () => void);
    hostConnected(): void;
    hostDisconnected(): void;
    /** A child was added or removed: re-attach if the `<datalist>` itself moved. */
    private onHostMutation;
    /** Watch the current `<datalist>`, if there is one. */
    private observeList;
}
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