Function defineFcn

src/backend/MountableFileSystem.ts:355–385

* Tricky: Define all of the functions that merely forward arguments to the * relevant file system, or return/throw an error. * Take advantage of the fact that the *first* argument is always the path, and * the *last* is the callback function (if async). * @todo Can use numArgs to make proxying m

(name: string, isSync: boolean, numArgs: number)

 * @hidden
 */
function defineFcn(name: string, isSync: boolean, numArgs: number): (...args: any[]) => any {
  if (isSync) {
    return function(this: MountableFileSystem, ...args: any[]) {
      const path = args[0];
      const rv = this._getFs(path);
      args[0] = rv.path;
      try {
        return (<any> rv.fs)[name].apply(rv.fs, args);
      } catch (e) {
        this.standardizeError(e, rv.path, path);
        throw e;
      }
    };
  } else {
    return function(this: MountableFileSystem, ...args: any[]) {
      const path = args[0];
      const rv = this._getFs(path);
      args[0] = rv.path;
      if (typeof args[args.length - 1] === 'function') {
        const cb = args[args.length - 1];
        args[args.length - 1] = (...args: any[]) => {
          if (args.length > 0 && args[0] instanceof ApiError) {
            this.standardizeError(args[0], rv.path, path);
          }
          cb.apply(null, args);
        };
      }
      return (<any> rv.fs)[name].apply(rv.fs, args);
    };
  }
}

/**
 * @hidden