import { FlagsResponse } from "./flags";
interface StorageItem {
    get(): string | null;
    set(value: string): void;
    clear(): void;
}
interface cacheEntry {
    expireAt: number;
    staleAt: number;
    success: boolean;
    flags: FlagsResponse | undefined;
    attemptCount: number;
}
export declare function validateFlags(flagsInput: any): FlagsResponse | undefined;
export interface CacheResult {
    flags: FlagsResponse | undefined;
    stale: boolean;
    success: boolean;
    attemptCount: number;
}
export declare class FlagCache {
    private storage;
    private staleTimeMs;
    private expireTimeMs;
    constructor(storage: StorageItem, staleTimeMs: number, expireTimeMs: number);
    set(key: string, { success, flags, attemptCount, }: {
        success: boolean;
        flags?: FlagsResponse;
        attemptCount: number;
    }): CacheData;
    get(key: string): CacheResult | undefined;
    clear(): void;
}
type CacheData = Record<string, cacheEntry>;
export declare function isObject(item: any): boolean;
export {};