export interface CompletionViewportBounds {
    readonly itemCount: number;
    readonly maxRows: number;
}
export interface CompletionViewportState {
    readonly offset: number;
    readonly selected: number;
    readonly hovered: number | undefined;
}
export type CompletionViewportAction = {
    readonly type: "reset";
    readonly selected?: number | undefined;
} | {
    readonly type: "reconcile";
    readonly selected?: number | undefined;
} | {
    readonly type: "select";
    readonly index: number;
} | {
    readonly type: "hover";
    readonly index: number | undefined;
} | {
    readonly type: "scroll";
    readonly rows: number;
};
export interface CompletionViewportWindow {
    readonly start: number;
    readonly end: number;
    readonly visibleCount: number;
    readonly before: number;
    readonly after: number;
}
export declare function completionVisibleCount(itemCount: number, maxRows: number): number;
export declare function clampCompletionViewport(offset: number, itemCount: number, maxRows: number): number;
export declare function keepCompletionSelectionVisible(offset: number, selected: number, itemCount: number, maxRows: number): number;
export declare function completionViewportWindow(itemCount: number, maxRows: number, offset: number): CompletionViewportWindow;
export declare function completionAbsoluteIndex(itemCount: number, maxRows: number, offset: number, visibleIndex: number): number | undefined;
export declare function completionWheelRows(direction: string, delta: number): number;
export declare function initialCompletionViewportState(): CompletionViewportState;
export declare function reduceCompletionViewport(state: CompletionViewportState, action: CompletionViewportAction, bounds: CompletionViewportBounds): CompletionViewportState;