text: //
  // Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2021
  //
  // Distributed under the Boost Software License, Version 1.0. (See accompanying
  // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  //
  #pragma once
  
  #include "td/utils/port/config.h"
  
  #include "td/utils/port/detail/NativeFd.h"
  #include "td/utils/port/detail/PollableFd.h"
  #include "td/utils/port/IoSlice.h"
  #include "td/utils/port/IPAddress.h"
  #include "td/utils/Slice.h"
  #include "td/utils/Span.h"
  #include "td/utils/Status.h"
  
  #include <memory>
  
  namespace td {
  
  namespace detail {
  class SocketFdImpl;
  class SocketFdImplDeleter {
   public:
    void operator()(SocketFdImpl *impl);
  };
  }  // namespace detail
  
  class SocketFd {
   public:
    SocketFd();
    SocketFd(const SocketFd &) = delete;
    SocketFd &operator=(const SocketFd &) = delete;
    SocketFd(SocketFd &&) noexcept;
    SocketFd &operator=(SocketFd &&) noexcept;
    ~SocketFd();
  
    static Result<SocketFd> open(const IPAddress &address) TD_WARN_UNUSED_RESULT;
  
    PollableFdInfo &get_poll_info();
    const PollableFdInfo &get_poll_info() const;
  
    Status get_pending_error() TD_WARN_UNUSED_RESULT;
  
    Result<size_t> write(Slice slice) TD_WARN_UNUSED_RESULT;
    Result<size_t> writev(Span<IoSlice> slices) TD_WARN_UNUSED_RESULT;
    Result<size_t> read(MutableSlice slice) TD_WARN_UNUSED_RESULT;
  
    const NativeFd &get_native_fd() const;
    static Result<SocketFd> from_native_fd(NativeFd fd);
  
    void close();
    bool empty() const;
  
   private:
    std::unique_ptr<detail::SocketFdImpl, detail::SocketFdImplDeleter> impl_;
    explicit SocketFd(unique_ptr<detail::SocketFdImpl> impl);
  };
  
  namespace detail {
  #if TD_PORT_POSIX
  Status get_socket_pending_error(const NativeFd &fd);
  #elif TD_PORT_WINDOWS
  Status get_socket_pending_error(const NativeFd &fd, WSAOVERLAPPED *overlapped, Status iocp_error);
  #endif
  }  // namespace detail
  
  }  // namespace td
  