reflection.h

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#ifndef _BBM_REFLECTION_CONCEPT_H_
#define _BBM_REFLECTION_CONCEPT_H_
 
#include <utility>
 
/************************************************************************/
/*! \file refection.h
 
  \brief attribute and parent class reflection contract.  To do: extend to
  include function and constructor reflection.
 
*************************************************************************/
 
namespace bbm {
 
  namespace reflection {
    // forward declaration
    template<typename T> struct bbm_enum;
  } // end reflection namespace
    
  namespace concepts {
    namespace reflection {
      
      /******************************************************************/
      /*! \brief attribute reflection allows to enumerate and direct access to
        the attributes of a class. A class supports reflection if the
        following typedef and two methods are implemented:
 
        + typename attribute_tuple_t                              : a named<tuple> of the types of the attributes (for a non-const struct)
        + named<std::tuple<...>, ...> attribute_tuple(void)       : returns a named<tuple> of references to the attributes
        + named<std::tuple<...>, ...> attribute_tuple(void) const : returns a named<tuple> of const references to the attributes
      *******************************************************************/
      template<typename T>
        concept attributes = requires(T t)
      {
        typename std::decay_t<T>::attribute_tuple_t;
        { t.attribute_tuple() };
        { std::as_const(t).attribute_tuple() };
      };
  
 
      /******************************************************************/
      /*! \brief basetypes reflection allows to enumerate all base classes.
          The class has the following typename:
        
        + typename reflection_base_t
      *******************************************************************/
      template<typename T>
        concept basetypes = requires
      {
        typename std::decay_t<T>::reflection_base_t;
      };
 
      /******************************************************************/
      /*! \brief concept to check if a class supports reflections
       ******************************************************************/
      template<typename T>
        concept supported = basetypes<T> || attributes<T>;
 
      
      /******************************************************************/
      /*! \brief concept to check if a enum supports reflection
       ******************************************************************/
      template<typename T>
        concept enumerate = requires
      {
        { bbm::reflection::bbm_enum<T>::values() };
      };
      
    } // end reflection namespace
  } // end concepts namespace
} // end bbm namespace
 
#endif /* _BBM_REFLECTION_CONCEPT_H_ */