foxts/dist/ts-xor/index.d.ts

Opinionated collection of common TypeScript utils by @SukkaW

/**
 * Skip evaluating `U` if `T` is `unknown`.
 */
type EvalIfNotUnknown<T, U> = unknown extends T ? never : U;
/**
 * Resolve mapped types and show the derived keys and their types when hovering in
 * VS Code, instead of just showing the names those mapped types are defined with.
 */
type Prettify<T> = {
    [K in keyof T]: T[K];
} & {};
/**
 * Get the keys of T without any keys of U.
 */
type Without<T, U> = {
    [P in Exclude<keyof T, keyof U>]?: never;
};

/**
 * Restrict using either exclusively the keys of `T` or exclusively the keys of `U`.
 *
 * No unique keys of `T` can be used simultaneously with any unique keys of `U`.
 *
 * @example
 * ```ts
 * const myVar: XOR<{ data: object }, { error: object }>
 * ```
 *
 * Supports from 2 up to 8 generic parameters.
 *
 * More: https://github.com/maninak/ts-xor/tree/master#description
 *  */
type XOR<A, B, C = unknown, D = unknown, E = unknown, F = unknown, G = unknown, H = unknown> = Prettify<(Without<B & C & D & E & F & G & H, A> & A) | (Without<A & C & D & E & F & G & H, B> & B) | EvalIfNotUnknown<C, Without<A & B & D & E & F & G & H, C> & C> | EvalIfNotUnknown<D, Without<A & B & C & E & F & G & H, D> & D> | EvalIfNotUnknown<E, Without<A & B & C & D & F & G & H, E> & E> | EvalIfNotUnknown<F, Without<A & B & C & D & E & G & H, F> & F> | EvalIfNotUnknown<G, Without<A & B & C & D & E & F & H, G> & G> | EvalIfNotUnknown<H, Without<A & B & C & D & E & F & G, H> & H>>;

export type { XOR };