cpp-useful-iterators/include/iterator/recursive/base.hpp

#pragma once

#include "../end_aware_iterator.hpp"
#include "traits.hpp"

namespace iterator::recursive {
  /**
   * @class recursive_iterator_base
   * @brief A thin wrapper around end_aware_iterator for the purposes of
   * template metaprogramming.
   */
  template <typename Iterator>
  class base : public end_aware_iterator<Iterator> {
  public:
    using super = end_aware_iterator<Iterator>;

  protected:
    using recursive_category =
        std::conditional_t<is_associative<Iterator>{}, continue_layer_tag_t,
                           terminal_layer_tag_t>;

  public:
    using super::super;
    base(super const & iter) : super(iter) {}
    base(super && iter) : super(std::move(iter)) {}

  protected:
    decltype(auto) get() const {
      if constexpr (is_associative<Iterator>{}) {
        return std::tie((**this).first, (**this).second);
      } else {
        return **this;
      }
    }
  };
}