aws-cdk/lib/util/type-brands.d.ts

CDK Toolkit, the command line tool for CDK apps

/**
 * Type branding
 *
 * This allows marking certain types as having gone through particular operations.
 *
 * Branded types can be used anywhere the base type is expected, but the base type
 * cannot be used where a branded type is expected; the values have to go through
 * a type assertion operation to confirm their brand.
 *
 * Usage:
 *
 * ```
 * type ValidatedString = Branded<string, 'PassedMyValidation'>;
 *
 * function validate(x: string): asserts x is ValidatedString {
 *   // ... throw an error if not
 * }
 *
 * function isValid(x: string): x is ValidatedString {
 *   // ... throw an error if not
 * }
 * ```
 */
declare const __brand: unique symbol;
export type Brand<B> = {
    [__brand]: B;
};
export type Branded<T, B> = T & Brand<B>;
/**
 * Marks a value as being branded a certain way.
 *
 * You should in general avoid calling this, and use validation or
 * asserting functions instead. However, this can be useful to produce
 * values which are branded by construction (really just an elaborate
 * way to write 'as').
 */
export declare function createBranded<A extends Branded<any, any>>(value: TypeUnderlyingBrand<A>): A;
type TypeUnderlyingBrand<A> = A extends Branded<infer T, any> ? T : never;
export {};