Program Listing for File single_instance.hpp

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// Copyright 2024 Beam Limited.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// @file      single_instance.hpp
// @author    Sławomir Cielepak (slawomir.cielepak@gmail.com)
// @date      2024-11-26
//
// @brief     Mock header for ROS 2 single instance class.

#pragma once

#include <atomic>
#include <stdexcept>
#include <string>
#include <typeinfo>

#include <boost/type_index.hpp>

namespace rtest
{

template <typename T>
class SingleInstance
{
public:
  SingleInstance()
  {
    if (instanceCreated_.test_and_set()) {
      throw std::runtime_error{
        std::string{"Attempt to create more than one instance of "} +
        boost::typeindex::type_id<T>().pretty_name()};
    }
  }

  ~SingleInstance() { instanceCreated_.clear(); }

private:
  static std::atomic_flag instanceCreated_;
};

template <typename T>
std::atomic_flag SingleInstance<T>::instanceCreated_ = ATOMIC_FLAG_INIT;

}  // namespace rtest