interface CacheInterface<T> {
    hasKey(key: string): boolean;
    get(key: string | undefined): T | undefined;
    set(key: string | undefined, item: CacheEntry<T>): void;
    clear(): void;
}
/**
 * Representation of a cached object.
 */
export interface CacheEntry<T> {
    /**
     * The expiration time of the cache entry in milliseconds.
     */
    expires?: number;
    /**
     * The cache entry.
     */
    entry: T;
}
/**
 * Options to enable caching when fetching destinations.
 */
export interface CachingOptions {
    /**
     * A boolean value that indicates whether to read and write destinations from and to cache.
     * This never writes destinations with authentication type "SAMLAssertion".
     */
    useCache?: boolean;
}
/**
 * Representation of a cache to transiently store objects locally for faster access.
 * @typeParam T - Type of the cache entries.
 * @internal
 */
export declare class Cache<T> implements CacheInterface<T> {
    private defaultValidityTime;
    /**
     * Object that stores all cached entries.
     */
    private cache;
    /**
     * Creates an instance of Cache.
     * @param defaultValidityTime - The default validity time in milliseconds. Use 0 for unlimited cache duration.
     */
    constructor(defaultValidityTime: number);
    /**
     * Clear all cached items.
     */
    clear(): void;
    /**
     * Specifies whether an entry with a given key is defined in cache.
     * @param key - The entry's key.
     * @returns A boolean value that indicates whether the entry exists in cache.
     */
    hasKey(key: string): boolean;
    /**
     * Getter of cached entries.
     * @param key - The key of the entry to retrieve.
     * @returns The corresponding entry to the provided key if it is still valid, returns `undefined` otherwise.
     */
    get(key: string | undefined): T | undefined;
    /**
     * Setter of entries in cache.
     * @param key - The entry's key.
     * @param item - The entry to cache.
     */
    set(key: string | undefined, item: CacheEntry<T>): void;
    private inferDefaultExpirationTime;
}
export {};