connection.hpp

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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2013-2023 Regents of the University of California.
 *
 * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
 *
 * ndn-cxx library is free software: you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later version.
 *
 * ndn-cxx library is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
 * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
 *
 * You should have received copies of the GNU General Public License and GNU Lesser
 * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
 * <http://www.gnu.org/licenses/>.
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 * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
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#ifndef NDN_CXX_UTIL_SIGNAL_CONNECTION_HPP
#define NDN_CXX_UTIL_SIGNAL_CONNECTION_HPP
 
#include "ndn-cxx/detail/common.hpp"
 
#include <boost/operators.hpp>
 
namespace ndn::signal {
 
using DisconnectFunction = std::function<void()>;
 
class Connection : private boost::equality_comparable<Connection>
{
public:
  constexpr
  Connection() noexcept = default;
 
  void
  disconnect();
 
  bool
  isConnected() const noexcept
  {
    return !m_disconnect.expired();
  }
 
private:
  explicit
  Connection(weak_ptr<DisconnectFunction> disconnect) noexcept;
 
  template<typename Owner, typename... TArgs>
  friend class Signal;
 
private: // non-member operators
  // NOTE: the following "hidden friend" operators are available via
  //       argument-dependent lookup only and must be defined inline.
  // boost::equality_comparable provides != operator.
 
  friend bool
  operator==(const Connection& lhs, const Connection& rhs) noexcept
  {
    return (!lhs.isConnected() && !rhs.isConnected()) ||
        (!lhs.m_disconnect.owner_before(rhs.m_disconnect) &&
         !rhs.m_disconnect.owner_before(lhs.m_disconnect));
  }
 
private:
  weak_ptr<DisconnectFunction> m_disconnect;
};
 
} // namespace ndn::signal
 
#endif // NDN_CXX_UTIL_SIGNAL_CONNECTION_HPP