import type { Constructor } from '@poppinss/utils/types';
/**
 * Type guard to check if value is a class constructor. Plain old
 * functions are not considered as class constructors.
 *
 * @param value - The value to check
 *
 * @example
 * ```ts
 * isClass(Database) // true
 * isClass(function foo() {}) // false
 * isClass(() => {}) // false
 * ```
 */
export declare function isClass<T>(value: unknown): value is Constructor<T>;
/**
 * Converts a function to a self-contained queue, where each call to
 * the function is queued until the first call resolves or rejects.
 *
 * After the first call, the value is cached and used forever.
 * This is used to implement singleton bindings in the container.
 *
 * @param callback - The function to enqueue
 *
 * @example
 * ```ts
 * const queuedFn = enqueue(async () => {
 *   return new Database()
 * })
 *
 * // First call executes the function
 * const db1 = await queuedFn()
 *
 * // Second call returns cached value
 * const db2 = await queuedFn()
 *
 * // db1 === db2.value
 * ```
 */
export declare function enqueue(callback: Function): (...args: any) => Promise<{
    value: any;
    cached: boolean;
}>;
/**
 * Dynamically import a module and ensure it has a default export
 *
 * @param importPath - The module path to import
 * @param parentURL - The parent URL for resolving the import path
 *
 * @example
 * ```ts
 * const UserController = await resolveDefault(
 *   '#controllers/users_controller',
 *   import.meta.url
 * )
 * ```
 */
export declare function resolveDefault(importPath: string, parentURL: URL | string): Promise<any>;