/**
 * Configuration options for TTLCache.
 */
export interface TTLCacheOptions {
    /** Default time-to-live in milliseconds for cache entries */
    defaultTTL: number;
    /** Optional maximum number of entries */
    maxSize?: number;
}
/**
 * A time-to-live (TTL) cache that automatically expires entries
 * after a configured duration.
 *
 * Uses lazy deletion: expired entries are only removed
 * when accessed via get() or has().
 *
 * ## Features
 * - **get(key)**: Retrieve a value (returns undefined if expired)
 * - **set(key, value, ttl?)**: Insert with optional per-entry TTL
 * - **has(key)**: Check if a non-expired key exists
 * - **delete(key)**: Remove a specific entry
 * - **clear()**: Remove all entries
 * - **size**: Get the number of entries (including expired)
 *
 * @example
 * ```typescript
 * const cache = new TTLCache<string, number>({ defaultTTL: 5000 });
 * cache.set("a", 1);
 * cache.get("a"); // 1
 *
 * // After 5 seconds...
 * cache.get("a"); // undefined (expired)
 * ```
 *
 * @template K - The type of cache keys
 * @template V - The type of cache values
 */
export declare class TTLCache<K, V> {
    private defaultTTL;
    private maxSize;
    private map;
    /**
     * Creates a new TTLCache instance.
     * @param options - Configuration options for the cache
     *
     * @example
     * ```typescript
     * const cache = new TTLCache<string, number>({
     *   defaultTTL: 60000,
     *   maxSize: 1000,
     * });
     * ```
     */
    constructor(options: TTLCacheOptions);
    /**
     * Returns the number of entries in the cache
     * (including potentially expired entries).
     * @returns The current number of entries
     *
     * @example
     * ```typescript
     * const cache = new TTLCache<string, number>({ defaultTTL: 5000 });
     * cache.set("a", 1);
     * console.log(cache.size); // 1
     * ```
     */
    get size(): number;
    /**
     * Retrieves a value by key. Returns undefined if the key
     * does not exist or has expired.
     * @param key - The key to look up
     * @returns The value if found and not expired, or undefined
     *
     * @example
     * ```typescript
     * const cache = new TTLCache<string, number>({ defaultTTL: 5000 });
     * cache.set("a", 1);
     * cache.get("a"); // 1
     * ```
     */
    get(key: K): V | undefined;
    /**
     * Inserts or updates a key-value pair with an optional TTL override.
     * If maxSize is configured and the cache is full, the oldest entry
     * is removed.
     * @param key - The key to set
     * @param value - The value to cache
     * @param ttl - Optional TTL in milliseconds (overrides defaultTTL)
     *
     * @example
     * ```typescript
     * const cache = new TTLCache<string, number>({ defaultTTL: 5000 });
     * cache.set("a", 1);
     * cache.set("b", 2, 10000); // custom 10s TTL
     * ```
     */
    set(key: K, value: V, ttl?: number): void;
    /**
     * Checks whether a non-expired key exists in the cache.
     * Removes the entry if it has expired.
     * @param key - The key to check
     * @returns True if the key exists and has not expired
     *
     * @example
     * ```typescript
     * const cache = new TTLCache<string, number>({ defaultTTL: 5000 });
     * cache.set("a", 1);
     * cache.has("a"); // true
     * cache.has("b"); // false
     * ```
     */
    has(key: K): boolean;
    /**
     * Removes an entry from the cache by key.
     * @param key - The key to remove
     * @returns True if the entry was found and removed
     *
     * @example
     * ```typescript
     * const cache = new TTLCache<string, number>({ defaultTTL: 5000 });
     * cache.set("a", 1);
     * cache.delete("a"); // true
     * cache.delete("b"); // false
     * ```
     */
    delete(key: K): boolean;
    /**
     * Removes all entries from the cache.
     *
     * @example
     * ```typescript
     * const cache = new TTLCache<string, number>({ defaultTTL: 5000 });
     * cache.set("a", 1);
     * cache.clear();
     * console.log(cache.size); // 0
     * ```
     */
    clear(): void;
}