import { Struct } from "@metamask/superstruct";
import type { Infer, ObjectSchema, OmitBy, Optionalize, PickBy, Simplify, AnyStruct } from "@metamask/superstruct";
import type { Equals } from "./types.mjs";
declare const ExactOptionalSymbol: unique symbol;
export type ExactOptionalTag = {
    type: typeof ExactOptionalSymbol;
};
/**
 * Exclude type `Type` from the properties of `Obj`.
 *
 * ```ts
 * type Foo = { a: string | null; b: number };
 * type Bar = ExcludeType<Foo, null>;
 * // Bar = { a: string, b: number }
 * ```
 */
export type ExcludeType<Obj, Type> = {
    [K in keyof Obj]: Exclude<Obj[K], Type>;
};
/**
 * Make optional all properties that have the `ExactOptionalTag` type.
 *
 * ```ts
 * type Foo = { a: string | ExactOptionalTag; b: number};
 * type Bar = ExactOptionalize<Foo>;
 * // Bar = { a?: string; b: number}
 * ```
 */
export type ExactOptionalize<Schema extends object> = OmitBy<Schema, ExactOptionalTag> & Partial<ExcludeType<PickBy<Schema, ExactOptionalTag>, ExactOptionalTag>>;
/**
 * Infer a type from an superstruct object schema.
 */
export type ObjectType<Schema extends ObjectSchema> = Simplify<ExactOptionalize<Optionalize<{
    [K in keyof Schema]: Infer<Schema[K]>;
}>>>;
/**
 * Change the return type of a superstruct's `object` function to support
 * exact optional properties.
 *
 * @param schema - The object schema.
 * @returns A struct representing an object with a known set of properties.
 */
export declare function object<Schema extends ObjectSchema>(schema: Schema): Struct<ObjectType<Schema>, Schema>;
/**
 * Change the return type of a superstruct's `type` function to support
 * exact optional properties.
 *
 * @param schema - The object schema.
 * @returns A struct representing an object with a known set of properties
 * and ignore unknown properties.
 */
export declare function type<Schema extends ObjectSchema>(schema: Schema): Struct<ObjectType<Schema>, Schema>;
/**
 * Augment a struct to allow exact-optional values. Exact-optional values can
 * be omitted but cannot be `undefined`.
 *
 * ```ts
 * const foo = object({ bar: exactOptional(string()) });
 * type Foo = Infer<typeof foo>;
 * // Foo = { bar?: string }
 * ```
 *
 * @param struct - The struct to augment.
 * @returns The augmented struct.
 */
export declare function exactOptional<Type, Schema>(struct: Struct<Type, Schema>): Struct<Type | ExactOptionalTag, Schema>;
/**
 * Assert that a value is valid according to a struct.
 *
 * It is similar to superstruct's mask function, but it does not ignore extra
 * properties.
 *
 * @param value - Value to check.
 * @param struct - Struct to validate the value against.
 * @param message - Error message to throw if the value is not valid.
 * @returns The value if it is valid.
 */
export declare function strictMask<Type, Schema>(value: unknown, struct: Struct<Type, Schema>, message?: string): Type;
/**
 * Extracts the type from a struct definition and asserts that it matches the
 * expected type. If the types do not match, the type `never` is returned.
 *
 * @param StructType - The struct type to infer.
 * @param ExpectedType - The expected type.
 */
export type InferEquals<StructType extends Struct<any, any>, ExpectedType> = Equals<Infer<StructType>, ExpectedType> extends true ? Infer<StructType> : never;
/**
 * Create a custom union struct that uses a `selector` function for choosing
 * the validation path.
 *
 * @param selector - The selector function choosing the struct to validate with.
 * @returns The `superstruct` struct, which validates that the value satisfies
 * one of the structs.
 */
export declare function selectiveUnion<Selector extends (value: any) => AnyStruct>(selector: Selector): Struct<Infer<ReturnType<Selector>>, null>;
export {};
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