cpp-lazy-stream/include/stream/algorithm/count.h

//
//  count.h
//  stream
//
//  Created by Sam Jaffe on 3/30/23.
//

#pragma once

#include <stream/forward.h>

#include <stream/detail/identity.h>

namespace stream::ranges {
template <typename It, typename S, typename T, typename Proj = detail::identity>
bool count(It it, S end, T const & value, Proj proj = {}) {
  size_t result = 0;
  for (; it != end; ++it) {
    if (value == std::invoke(proj, *it)) { ++result; }
  }
  return result;
}

template <typename Stream, typename T, typename Proj = detail::identity>
bool count(Stream const & stream, T const & value, Proj proj = {}) {
  return count(stream.begin(), stream.end(), value, std::ref(proj));
}
}