A Go-style C++ wrapper for libmpdclient

go_style_libmpdclient.cpp

#include <iostream>
#include <memory>
#include <mpd/client.h>
#include <string>
#include <tuple>
#include <vector>

namespace mpd {
using namespace std::string_literals;

typedef std::unique_ptr<mpd_connection, decltype(&mpd_connection_free)> connection;

auto get_error(const connection &conn) {
  mpd_error error_code{mpd_connection_get_error(conn.get())};

  if (MPD_ERROR_SUCCESS != error_code) {
    std::string message{mpd_connection_get_error_message(conn.get())};
    return std::make_tuple(error_code, message);
  }

  return std::make_tuple(error_code, ""s);
}

auto connection_new(const char *host, unsigned port, unsigned timeout_ms) {
  auto ptr{mpd_connection_new(host, port, timeout_ms)};
  connection conn(ptr, &mpd_connection_free);

  if (!conn) {
    return std::make_tuple(std::move(conn), MPD_ERROR_OOM, ""s);
  }

  auto [error_code, error_message] = get_error(conn);
  return std::make_tuple(std::move(conn), error_code, error_message);
}

auto search_db_tags(const connection &conn, mpd_tag_type tag_type) {
  if (mpd_search_db_tags(conn.get(), tag_type)) {
    return std::make_tuple(MPD_ERROR_SUCCESS, ""s);
  }

  return get_error(conn);
}

auto search_commit(const connection &conn) {
  if (mpd_search_commit(conn.get())) {
    return std::make_tuple(MPD_ERROR_SUCCESS, ""s);
  }

  return get_error(conn);
}

auto recv_tags(const connection &conn, mpd_tag_type tag_type) {
  std::vector<std::string> tags;

  mpd_pair *pair{};
  while ((pair = mpd_recv_pair_tag(conn.get(), tag_type)) != nullptr) {
    tags.emplace_back(pair->value);
    mpd_return_pair(conn.get(), pair);
  }

  auto [error_code, message] = get_error(conn);
  return std::make_tuple(std::move(tags), error_code, message);
}
}; // namespace mpd

int main() {
  auto [connection, error_code, error_message] = mpd::connection_new("localhost", 6600, 0);

  if (MPD_ERROR_SUCCESS != error_code) {
    std::cout << error_message << "\n";
    return 1;
  }

  std::tie(error_code, error_message) = mpd::search_db_tags(connection, MPD_TAG_ALBUM);
  if (MPD_ERROR_SUCCESS != error_code) {
    std::cout << error_message << "\n";
    return 1;
  }

  std::tie(error_code, error_message) = mpd::search_commit(connection);
  if (MPD_ERROR_SUCCESS != error_code) {
    std::cout << error_message << "\n";
    return 1;
  }

  std::vector<std::string> tags;
  std::tie(tags, error_code, error_message) = mpd::recv_tags(connection, MPD_TAG_ALBUM);

  if (MPD_ERROR_SUCCESS != error_code) {
    std::cout << error_message << "\n";
    return 1;
  }

  for (auto tag : tags) {
    std::cout << tag << "\n";
  }

  return 0;
}