function mountMemo<T>(
  nextCreate: () => T, // 执行函数
  deps: Array<mixed> | void | null,
): T {
  const hook = mountWorkInProgressHook();
  const nextDeps = deps === undefined ? null : deps;
  const nextValue = nextCreate(); // 执行函数返回值
  hook.memoizedState = [nextValue, nextDeps]; // 保存依赖和值
  return nextValue;
}

function updateMemo<T>(
  nextCreate: () => T,
  deps: Array<mixed> | void | null,
): T {
  const hook = updateWorkInProgressHook();
  const nextDeps = deps === undefined ? null : deps;
  const prevState = hook.memoizedState;
  if (prevState !== null) {
    if (nextDeps !== null) {
      const prevDeps: Array<mixed> | null = prevState[1];
      if (areHookInputsEqual(nextDeps, prevDeps)) {
	      // 依赖没有变化返回旧的value
        return prevState[0];
      }
    }
  }
  // 依赖变化，重新创建 value
  const nextValue = nextCreate();
  hook.memoizedState = [nextValue, nextDeps];
  return nextValue;
}

function mountCallback<T>(
	callback: T, deps: Array<mixed> | void | null
): T {
  const hook = mountWorkInProgressHook();
  const nextDeps = deps === undefined ? null : deps;
  hook.memoizedState = [callback, nextDeps]; // 记录 cb 和 依赖
  return callback;
}

function updateCallback<T>(callback: T, deps: Array<mixed> | void | null): T {
  const hook = updateWorkInProgressHook();
  const nextDeps = deps === undefined ? null : deps;
  const prevState = hook.memoizedState;
  if (prevState !== null) {
    if (nextDeps !== null) {
      const prevDeps: Array<mixed> | null = prevState[1];
      // 依赖没有变化
      if (areHookInputsEqual(nextDeps, prevDeps)) {
        return prevState[0];
      }
    }
  }
  hook.memoizedState = [callback, nextDeps];
  return callback;
}