type-graphql/build/typings/typings/utils/MergeExclusive.d.ts

Create GraphQL schema and resolvers with TypeScript, using classes and decorators!

type Without<FirstType, SecondType> = {
    [KeyType in Exclude<keyof FirstType, keyof SecondType>]?: never;
};
/**
Create a type that has mutually exclusive keys.

This type was inspired by [this comment](https://github.com/Microsoft/TypeScript/issues/14094#issuecomment-373782604).

This type works with a helper type, called `Without`. `Without<FirstType, SecondType>` produces a type that has only keys from `FirstType` which are not present on `SecondType` and sets the value type for these keys to `never`. This helper type is then used in `MergeExclusive` to remove keys from either `FirstType` or `SecondType`.

@example
```
import {MergeExclusive} from 'type-fest';

interface ExclusiveVariation1 {
    exclusive1: boolean;
}

interface ExclusiveVariation2 {
    exclusive2: string;
}

type ExclusiveOptions = MergeExclusive<ExclusiveVariation1, ExclusiveVariation2>;

let exclusiveOptions: ExclusiveOptions;

exclusiveOptions = {exclusive1: true};
//=> Works
exclusiveOptions = {exclusive2: 'hi'};
//=> Works
exclusiveOptions = {exclusive1: true, exclusive2: 'hi'};
//=> Error
```
*/
export type MergeExclusive<FirstType, SecondType> = FirstType | SecondType extends object ? (Without<FirstType, SecondType> & SecondType) | (Without<SecondType, FirstType> & FirstType) : FirstType | SecondType;
export {};