/**
 * LRU Cache with TTL (Time To Live)
 *
 * Provides a cache implementation with:
 * - TTL (Time To Live) expiration
 * - Size limits with LRU eviction
 * - Type-safe generic interface
 *
 * @example
 * ```typescript
 * const cache = new LRUCache<string, User>({ maxSize: 100, ttlMs: 5 * 60 * 1000 })
 * const user = await cache.fetch('user:123', () => fetchUserFromDB('123'))
 * ```
 */
export interface LRUCacheOptions {
    /**
     * Maximum number of entries in the cache
     * @default 100
     */
    maxSize?: number;
    /**
     * Time to live in milliseconds
     * @default 5 minutes (300000)
     */
    ttlMs?: number;
}
/**
 * LRU Cache with TTL for storing key-value pairs
 *
 * Features:
 * - Automatic expiration based on TTL
 * - Size limits with LRU (Least Recently Used) eviction
 * - Type-safe generic interface
 */
export declare class LRUCache<K = string, V = unknown> {
    private cache;
    private readonly maxSize;
    private readonly ttlMs;
    constructor(options?: LRUCacheOptions);
    /**
     * Fetch a value from cache or compute it using the fetcher function
     *
     * @param key - Cache key
     * @param fetcher - Function to fetch the value if not in cache
     * @returns The cached or newly fetched value
     */
    fetch(key: K, fetcher: () => Promise<V> | V): Promise<V>;
    /**
     * Get a value from cache without fetching (returns undefined if not found or expired)
     *
     * @param key - Cache key
     * @returns The cached value or undefined
     */
    get(key: K): V | undefined;
    /**
     * Set a value in the cache
     *
     * @param key - Cache key
     * @param value - Value to cache
     */
    set(key: K, value: V): void;
    /**
     * Delete a value from the cache
     *
     * @param key - Cache key
     * @returns true if the entry was deleted, false if it didn't exist
     */
    delete(key: K): boolean;
    /**
     * Clear all entries from the cache
     */
    clear(): void;
    /**
     * Get the current size of the cache
     */
    get size(): number;
    /**
     * Evict expired entries and LRU entries if at capacity
     */
    private evictIfNeeded;
    /**
     * Clean up expired entries (can be called periodically)
     */
    cleanup(): void;
}
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