cpp-lazy-stream/include/stream/iterator.hpp

//
//  iterator.hpp
//  stream
//
//  Created by Sam Jaffe on 3/28/23.
//

#pragma once
#include "detail/ifd_pointer.hpp"

#include <iterator/facade.h>

namespace stream {
  template <typename T>
  class iterator : public ::iterator::facade<iterator<T>> {
  private:
    T (*dereference_)(void *){nullptr};
    bool (*equal_to_)(void *, void *){nullptr};
    void (*increment_)(void *){nullptr};
    char const * type_{nullptr};
    detail::ifd_pointer impl_{};

  public:
    iterator() = default;

    template <typename Iter>
    iterator(Iter impl)
        : dereference_([](void * p) -> T { return **((Iter *)p); }),
          equal_to_(
              [](void * l, void * r) { return *((Iter *)l) == *((Iter *)r); }),
          increment_([](void * p) { ++(*(Iter *)(p)); }),
          type_(typeid(Iter).name()), impl_(std::forward<Iter>(impl)) {}

    T dereference() const { return dereference_(impl_.get()); }
    void increment() { increment_(impl_.get()); }
    bool equal_to(iterator const & other) const {
      return impl_ == other.impl_ ||
             (impl_ && other.impl_ &&
              equal_to_(impl_.get(), other.impl_.get()));
    }
  };

  template <typename Iter>
  iterator(Iter) -> iterator<typename std::iterator_traits<Iter>::reference>;
}

MAKE_ITERATOR_FACADE_TYPEDEFS_T(::stream::iterator);