type MergerFunc<T> = (base: T, layer: T) => T;
type Merger<T> = MergerFunc<T> | ConfigMerger<T>;
type MergerMap<T> = {
    [K in keyof T]?: Merger<T[K]>;
};
type PreTransformer<T> = (value: Partial<T>) => Partial<T>;
export declare const RESET_TOKEN: unique symbol;
export type ResetObject = {
    [RESET_TOKEN]?: any;
};
export declare class ConfigMerger<T> {
    preTransform?: PreTransformer<T>;
    constructor(map?: MergerMap<T>, preTransform?: PreTransformer<T>);
    private keyMergers;
    mergeConfigs(base: T, ...layers: Partial<(T & ResetObject)>[]): T;
    defineMergeHandler<K extends keyof T>(key: K | K[], merger: MergerFunc<T[K]> | ConfigMerger<T[K]>): void;
}
export declare function merger<T>(spec?: MergerMap<T>, preTransform?: PreTransformer<T>): ConfigMerger<T>;
export {};