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

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

#pragma once

#include <iterator/facade.h>

#include <stream/forward.h>

#include <stream/detail/traits.h>

#include <stream/detail/macro.h>

namespace stream::ranges {

template <typename T, typename Bound>
class iota_iterator : public facade<iota_iterator<T, Bound>,
                                    iterator::category::random_access> {
public:
  using sentinal_type =
      std::conditional_t<std::is_same_v<T, Bound>, void, Bound>;

  iota_iterator() = default;
  iota_iterator(T value) : value_(value) {}

  T dereference() const { return value_; }
  void advance(std::ptrdiff_t off) { value_ += off; }
  std::ptrdiff_t distance_to(iota_iterator const & other) const {
    return other.value_ - value_;
  }

  SFINAE((detail::is_sized_sentinel_v<T, Bound>))
  friend bool operator-(Bound bound, iota_iterator const & self) {
    return bound - self.value_;
  }

private:
  T value_;
};

}

#include <stream/detail/undef.h>