How do I efficiently remove_if only a single element from a forward_list?

Question

Well I think the question pretty much sums it up. I have a forward_list of unique items, and want to remove a single item from it:

std::forward_list         


        

Answer 1

There is nothing in the standard library which would be directly applicable. Actually, there is. See @TemplateRex's answer for that.

You can also write this yourself (especially if you want to combine the search with the erasure), something like this:

template 
bool remove_first_if(std::forward_list &list, Predicate pred)
{
  auto itErase = list.before_begin();
  auto itFind = list.begin();
  const auto itEnd = list.end();
  while (itFind != itEnd) {
    if (pred(*itFind)) {
      list.erase_after(itErase);
      return true;
    } else {
      ++itErase;
      ++itFind;
    }
  }
  return false;
}