text: // Copyright 2021 RobosoftAI Inc.
  //
  // 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.
  
  #pragma once
  
  namespace smacc2
  {
  template <typename T, typename TransitionTagName>
  class HasSpecificNamedOnExit
  {
    template <typename U, void (U::*)(TransitionTagName)>
    struct Check;
    template <typename U>
    static char func(Check<U, &U::onExit> *);
    template <typename U>
    static int func(...);
  
  public:
    typedef HasSpecificNamedOnExit type;
    enum
    {
      value = sizeof(func<T>(0)) == sizeof(char)
    };
  };
  
  template <typename TState, typename TTransitionTagName>
  void specificNamedOnExit(TState & st, TTransitionTagName tn, std::true_type)
  {
    st.onExit(tn);
  }
  
  template <typename TState, typename TTransitionTagName>
  void specificNamedOnExit(TState &, TTransitionTagName, std::false_type)
  {
  }
  
  template <typename TState, typename TTransitionTagName>
  void specificNamedOnExit(TState & m, TTransitionTagName tn)
  {
    specificNamedOnExit(
      m, tn,
      std::integral_constant<bool, HasSpecificNamedOnExit<TState, TTransitionTagName>::value>());
  }
  
  //-------------------------------------------------
  
  template <typename T>
  class HasStandardOnExit
  {
    template <typename U, void (U::*)()>
    struct Check;
    template <typename U>
    static char func(Check<U, &U::onExit> *);
    template <typename U>
    static int func(...);
  
  public:
    typedef HasStandardOnExit type;
    enum
    {
      value = sizeof(func<T>(0)) == sizeof(char)
    };
  };
  
  template <typename TState>
  void standardOnExit(TState & st, std::true_type)
  {
    st.onExit();
  }
  
  template <typename TState>
  void standardOnExit(TState &, std::false_type)
  {
  }
  
  template <typename TState>
  void standardOnExit(TState & m)
  {
    standardOnExit(m, std::integral_constant<bool, HasStandardOnExit<TState>::value>());
  }
  
  }  // namespace smacc2
  