Scalar.h

/**************************************************************************
 * basf2 (Belle II Analysis Software Framework)                           *
 * Author: The Belle II Collaboration                                     *
 *                                                                        *
 * See git log for contributors and copyright holders.                    *
 * This file is licensed under LGPL-3.0, see LICENSE.md.                  *
 **************************************************************************/
#pragma once
 
#include <type_traits>
 
namespace Belle2 {
  namespace TrackFindingCDC {
 
    template<class T>
    class Scalar {
    public:
      explicit Scalar(T obj)
        : m_obj(obj)
      {
      }
 
      operator T& ()& {
        return m_obj;
      }
 
      operator T const& () const&
      {
        return m_obj;
      }
 
      T operator->() const
      {
        return m_obj;
      }
 
      typename std::remove_pointer<T>::type& operator*() const
      {
        return *m_obj;
      }
 
      bool operator<(const Scalar<T>& rhs) const
      {
        return m_obj < rhs.m_obj;
      }
 
      bool operator==(const Scalar<T>& rhs) const
      {
        return m_obj == rhs.m_obj;
      }
 
    private:
      T m_obj;
    };
 
    template<class T, bool a_isScalar = false>
    struct ScalarToClassImpl {
      using type = T;
    };
 
    template<class T>
    struct ScalarToClassImpl<T, true> {
      using type = Scalar<T>;
    };
 
    template<class T>
    using ScalarToClass = typename ScalarToClassImpl<T, std::is_scalar<T>::value>::type;
  }
}