.. _program_listing_file_include_rtest_single_instance.hpp:

Program Listing for File single_instance.hpp
============================================

|exhale_lsh| :ref:`Return to documentation for file <file_include_rtest_single_instance.hpp>` (``include/rtest/single_instance.hpp``)

.. |exhale_lsh| unicode:: U+021B0 .. UPWARDS ARROW WITH TIP LEFTWARDS

.. code-block:: cpp

   // 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