Better way to move objects from one std::deque to another?

Question

If I have two std::deques, and I want to move the first n objects from the beginning of one to the beginning of the other, what is the best way to do that? Doing the following:

template <typename T>
void fn(std::deque<T>& src)
{
  std::deque<T> storage;
  size_t i = /* some calculated value between 0 and src.size() */;
  storage.insert(storage.begin(), src.begin(), src.begin()+i);
  src.erase(src.begin(), src.begin()+i);

  // ... other stuff ...
}

would create copies of the T objects. I guess I could do something like (not tested, as example only):

template <typename T>
void fn(std::deque<T>& src)
{
  std::deque<T> storage;
  size_t i = /* some calculated value between 0 and src.size() */;
  for (auto& it = std::reverse_iterator<decltype(src.begin()>(src.begin()+i)
    ; it != std::reverse_iterator<decltype<src.begin()>(src.begin())
    ; ++it)
  {
    storage.push_front(std::move(*it));
  }
  src.erase(src.begin(), src.begin()+i);

  // ... other stuff ...
}

but I'm wondering, is there an algorithm that would already handle this?

Answer 1

Use a move iterator by calling std::make_move_iterator:

storage.insert(storage.begin(),
  std::make_move_iterator(src.begin()),
  std::make_move_iterator(src.begin()+i));

src.erase(src.begin(), src.begin()+i);