TODO.md

• Survey the use of projections. Do they only apply when evaluating predicates, or are they like full input transformations? (E.g, does copy get a projection parameter or not? Does the projection get applied by e.g. set_difference?)

• Add contiguous iterator utilities. How about is_contiguous_iterator and as_contiguous_range:

  template<typename I, typename S,
      CONCEPT_REQUIRES_(RandomAccessIterator<I>() &&
                        SizedSentinel<S, I>() &&
                        is_contiguous_iterator<I>())>
  iterator_range<std::add_pointer_t<iterator_reference_t<I>>>
  as_contiguous_range(I begin, S end)
  {
      if(begin == end)
          return {nullptr, nullptr};
      else
          return {addressof(*begin), addressof(*begin) + (end - begin)};
  }
  

• Longer-term goals:

  • Make inplace_merge work with forward iterators
  • Make the sorting algorithms work with forward iterators
  • Study the impact of allowing ForwardIterator to return proxies

• Maybe iterators are not necessarily countable. Is there a relation between the ability to be able to subtract two iterators to find the distance, and with the existence of a DistanceType associated type? Think of:

  • counted iterators (subtractable regardless of traversal category)
  • repeat_view iterators (not subtractable but could be random access otherwise)
  • infinite ranges (only countable with an infinite precision integer which we lack)

• Add an optional extra argument to view::join for an element or sequence to be inserted between the joined sequences.