cpp-lazy-stream/include/stream/for_each.h

//
//  for_each.h
//  stream
//
//  Created by Sam Jaffe on 3/29/23.
//

#pragma once

#include <stream/detail/identity.h>
#include <stream/detail/named_pair.h>

#define FWD(x) std::forward<decltype(x)>(x)

namespace stream::ranges {
template <typename It, typename S, typename F, typename Proj = detail::identity>
auto for_each(It it, S end, F func, Proj proj = {}) {
  for (; it != end; ++it) {
    std::invoke(func, std::invoke(proj, FWD(*it)));
  }
  return detail::in_fun_result(it, std::move(func));
}

template <typename Stream, typename F, typename Proj = detail::identity>
auto for_each(Stream && stream, F func, Proj proj = {}) {
  return for_each(stream.begin(), stream.end(), std::move(func),
                  std::move(proj));
}
}

#undef FWD