import type { DeepMerge } from '@stacksjs/types';
/**
 * Map key/value pairs for an object, and construct a new one
 *
 *
 * @category Object
 *
 * Transform:
 * @example
 * ```
 * objectMap({ a: 1, b: 2 }, (k, v) => [k.toString().toUpperCase(), v.toString()])
 * // { A: '1', B: '2' }
 * ```
 *
 * Swap key/value:
 * @example
 * ```
 * objectMap({ a: 1, b: 2 }, (k, v) => [v, k])
 * // { 1: 'a', 2: 'b' }
 * ```
 *
 * Filter keys:
 * @example
 * ```
 * objectMap({ a: 1, b: 2 }, (k, v) => k === 'a' ? undefined : [k, v])
 * // { b: 2 }
 * ```
 */
export declare function objectMap<K extends string, V, NK = K, NV = V>(obj: Record<K, V>, fn: (key: K, value: V) => [NK, NV] | undefined): Record<K, V>;
/**
 * Type guard for any key, `k`.
 * Marks `k` as a key of `T` if `k` is in `obj`.
 *
 * @category Object
 * @param obj object to query for key `k`
 * @param k key to check existence in `obj`
 */
export declare function isKeyOf<T extends object>(obj: T, k: keyof any): k is keyof T;
/**
 * Strict typed `Object.keys`
 *
 * @category Object
 */
export declare function objectKeys<T extends object>(obj: T): void;
/**
 * Strict typed `Object.entries`
 *
 * @category Object
 */
export declare function objectEntries<T extends object>(obj: T): void;
/**
 * Deep merge :P
 *
 * @category Object
 */
export declare function deepMerge<T extends object = object, S extends object = T>(target: T, ...sources: S[]): DeepMerge<T, S>;
/**
 * Create a new subset object by providing keys.
 *
 * @category Object
 */
export declare function objectPick<O extends object, T extends keyof O>(obj: O, keys: T[], omitUndefined?: boolean): Pick<O, T>;
/**
 * Clear undefined fields from an object. It mutates the object.
 *
 * @category Object
 */
export declare function clearUndefined<T extends object>(obj: T): T;
/**
 * Determines whether an object has a property with the specified name
 *
 * @category Object
 */
export declare function hasOwnProperty<T>(obj: T, v: PropertyKey): boolean;