tgrid/src/typings/Promisive.ts

Grid Computing Framework for TypeScript

import { Functional } from "./Functional";
import { OmitEdgeUnderscored } from "./OmitEdgeUnderscored";
import { RemoveNever } from "./RemoveNever";
import { ValueOf } from "./ValueOf";

/**
 * Promisify an object type.
 *
 * It promisifies all member types. When a member type is:
 *
 *   - function: returns `Promise` (`R` -> `Promise<R>`).
 *   - object: promisifies recursively (`O` -> `Promisify<O>`).
 *   - atomic value: be ignored (be `never` type).
 *
 * @template Instance An object type to be promised.
 * @template UseParametric Whether to convert type of function parameters to be compatible with their pritimive.
 */
export type Promisive<
  Instance extends object,
  UseParametric extends boolean = false,
> = RemoveNever<
  OmitEdgeUnderscored<
    {
      [P in keyof Instance]: Instance[P] extends Function
        ? Functional<Instance[P], UseParametric> // function, its return type would be capsuled in the Promise
        : ValueOf<Instance[P]> extends object
          ? Instance[P] extends object
            ? Promisive<Instance[P], UseParametric> // object would be promisified
            : never // cannot be
          : never; // atomic value
    } & IRemoteObject
  >
>;

/**
 * Restrictions for Remote Object
 */
interface IRemoteObject {
  /**
   * Remote Object does not allow access to the `constructor`.
   */
  constructor: never;

  /**
   * Remote Object does not allow access to the `prototype`.
   */
  prototype: never;
}