cpp-lazy-stream/include/stream/iterator/any_iterator.h

//
//  any_iterator.h
//  stream
//
//  Created by Sam Jaffe on 4/6/23.
//

#pragma once

#include <iterator/facade.h>

#include <stream/forward.h>

#include <stream/detail/adaptor.h>

namespace stream::ranges {
template <typename T>
class any_iterator
    : public facade<any_iterator<T>, iterator::category::forward> {
private:
  typename detail::adaptor<T>::dereference_t dereference_;
  typename detail::adaptor<T>::equal_to_t equal_to_;
  typename detail::adaptor<T>::increment_t increment_;
  std::shared_ptr<void> impl_{nullptr};

public:
  template <typename It, typename IFD = detail::adaptor<T, It>>
  any_iterator(It impl)
      : dereference_(IFD::dereference()), equal_to_(IFD::equal_to()),
        increment_(IFD::increment()), impl_(std::make_shared<It>(impl)) {}

  T dereference() const { return dereference_(impl_.get()); }

  void increment() { increment_(impl_.get()); }

  bool equal_to(any_iterator const & other) const {
    return impl_ == other.impl_ ||
           (impl_ && other.impl_ && equal_to_(impl_.get(), other.impl_.get()));
  }
};
}