@stencil/utils/src/utils/promisify.ts

Dev tools to improve cross platform experiences.

export interface Promisify {
  <T>(func: (callback: (err: any, result: T) => void) => void): () => Promise<T>;
  <T, A1>(func: (arg1: A1, callback: (err: any, result: T) => void) => void): (arg1: A1) => Promise<T>;
  <T, A1, A2>(func: (arg1: A1, arg2: A2, callback: (err: any, result: T) => void) => void): (arg1: A1, arg2: A2) => Promise<T>;
  <T, A1, A2, A3>(func: (arg1: A1, arg2: A2, arg3: A3, callback: (err: any, result: T) => void) => void): (arg1: A1, arg2: A2, arg3: A3) => Promise<T>;
  <T, A1, A2, A3, A4>(func: (arg1: A1, arg2: A2, arg3: A3, arg4: A4, callback: (err: any, result: T) => void) => void): (arg1: A1, arg2: A2, arg3: A3, arg4: A4) => Promise<T>;
  <T, A1, A2, A3, A4, A5>(func: (arg1: A1, arg2: A2, arg3: A3, arg4: A4, arg5: A5, callback: (err: any, result: T) => void) => void): (arg1: A1, arg2: A2, arg3: A3, arg4: A4, arg5: A5) => Promise<T>;
}
/**
 * @example: const rReadFile = promisify<Buffer, string>(fs.readFile);
 *
 */
export const promisify: Promisify = function(func: Function) {
  return (...args: any[]) => {
    return new Promise((resolve, reject) => {
      func(...args, (err: any, response: any) => {
        if (err) {
          return reject(err);
        }
        if (response) {
          return resolve(response);
        }
        resolve();
      });
    });
  };
};

export interface PromisifyNoResult {
  <A1>(func: (arg1: A1, callback: (err: any) => void) => void): (arg1: A1) => Promise<undefined>;
  <A1, A2>(func: (arg1: A1, arg2: A2, callback: (err: any) => void) => void): (arg1: A1, arg2: A2) => Promise<undefined>;
}

export const promisifyNr: PromisifyNoResult = function(func: Function) {
  return (...args: any[]): Promise<undefined> => {
    return new Promise((resolve, reject) => {
      func(...args, (err: any) => {
        if (err) {
          return reject(err);
        }
        resolve();
      });
    });
  };
};