/*!
 * \file   include/TFEL/Metaprogramming/HasConstIterator.hxx
 * \brief  
 * 
 * \author Thomas Helfer
 * \date   19 oct 2006
 * \copyright Copyright (C) 2006-2018 CEA/DEN, EDF R&D. All rights 
 * reserved. 
 * This project is publicly released under either the GNU GPL Licence 
 * or the CECILL-A licence. A copy of thoses licences are delivered 
 * with the sources of TFEL. CEA or EDF may also distribute this 
 * project under specific licensing conditions. 
 */

#ifndef LIB_TFEL_HASCONSTITERATOR_HXX
#define LIB_TFEL_HASCONSTITERATOR_HXX 

#include"TFEL/Config/TFELConfig.hxx"
#include<type_traits>

namespace tfel{

  namespace meta{

    /*!
     * \class HasConstIterator
     * \param typename A, type tested.
     * \return bool cond, true if the type defines the iterator.
     */
    template<typename A>
    class TFEL_VISIBILITY_LOCAL HasConstIterator
    {
      /*!
       * \brief A first type.
       */
      typedef char Small;
      /*!
       * \brief A Second type which size is higher than Small
       */
      struct Big{Small dummy[2];};
      /*!
       * \brief a substitute for classes that have only protected constructors
       */
      template<typename B>
      struct Subs
      {};

    protected:

      /*
       * A Test fonction which returns a Small.
       * Can only be called if B defines a const_iterator.
       */
      template<typename B>
      static typename std::enable_if<
	sizeof(typename B::const_iterator)!=0,
	Small
      >::type
      Test(const Subs<B>);

      /*
       * A Test fonction which returns a Big.
       * It is called only if B does not defines a const_iterator.
       */
      static Big Test(...);

      /*!
       * \brief A function returning a T.
       * A small trick for classes that are not default constructible.
       */
      static Subs<A> MakeSubsA();

    public:

      /*
       * The result of the metafunction.
       */
      static constexpr bool cond = sizeof(Test(MakeSubsA()))==sizeof(Small);

    };

  } // end of namespace meta

} // end of namespace tfel  

#endif /* LIB_TFEL_HASCONSTITERATOR_HXX */