immutable-class/src/utils/utils.ts

A template for creating immutable classes

/*
 * Copyright 2015-2019 Imply Data, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * Check to see if things are an array of instances of the given constructor
 * Uses instanceof internally
 * @param things - the array of things to test
 * @param constructor - the constructor class to check against
 * @returns {boolean}
 */
export function isArrayOf(things: any, constructor: any): boolean {
  if (!Array.isArray(things)) return false;
  for (let i = 0, length = things.length; i < length; i++) {
    if (!(things[i] instanceof constructor)) return false;
  }
  return true;
}

/**
 * Does a quick 'duck typing' test to see if the given parameter is an immutable class
 * @param thing - the thing to test
 * @returns {boolean}
 */
export function isImmutableClass(thing: any): boolean {
  if (!thing || typeof thing !== 'object') return false;
  const ClassFn = thing.constructor;
  return (
    typeof ClassFn.fromJS === 'function' && // Has Class.fromJS
    typeof thing.toJS === 'function' && // Has Class#toJS
    typeof thing.equals === 'function'
  ); // Has Class#equals
}

/**
 * Does a nothing but a simple typecheck assertion
 * @param thing - the thing to typecheck
 */
export function typeCheck<T>(_x: T): void {}