import { type PartialWithUndefined } from '@augment-vir/common';
import { type TOptionalWithFlag, type TUndefined, type TUnion } from '@sinclair/typebox';
import { type Shape, type ShapeInitSchema } from '../shape/shape.js';
/**
 * Creates a shape that allows an object property to be missing.
 *
 * @category Shape
 * @example
 *
 * ```ts
 * import {optionalShape, checkValidShape, defineShape} from 'object-shape-tester';
 *
 * const myShape = defineShape({
 *     a: '',
 *     b: optionalShape(-1),
 * });
 *
 * checkValidShape({a: 'hi', b: 0}, myShape); // `true`
 * checkValidShape({a: 'hi'}, myShape); // `true`
 * checkValidShape({b: 0}, myShape); // `false`
 * ```
 */
export declare function optionalShape<T, const AlsoUndefined extends boolean = false>(shape: T, options?: PartialWithUndefined<{
    /**
     * - `true`: Allow the optional property to be present and possibly `undefined`.
     * - `false`: If the property is present, it cannot be `undefined`.
     *
     * @default `false`
     */
    alsoUndefined: AlsoUndefined;
}>): Shape<TOptionalWithFlag<AlsoUndefined extends true ? TUnion<[
    TUndefined,
    ShapeInitSchema<T>
]> : ShapeInitSchema<T>, true>>;