utl/include/utl/meta/logical.h

/*!
 * \file    logical.h
 * \brief   Template meta-programming logic operator and type relations.
 *
 * Copyright (C) 2018-2019 Christos Choutouridis
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#ifndef __utl_meta_logical_h__
#define __utl_meta_logical_h__

#include <utl/core/impl.h>
#include <utl/meta/selection.h>

/*!
 * \ingroup meta
 * \defgroup logic
 * logic operator and type relations support header
 */
//! @{
namespace utl {
namespace meta{

   /*!
    * Logical relation for types
    */
   //! @{

   //! Negate the *bool* constant parameter
   template <bool B>
   using not_c = bool_<!B>;

   //! not
   template<typename _Tp>
   using not_ = not_c<_Tp::type::value>;

   //! OR implementation
   //! @{
   namespace detail {
      template<typename...> struct _or_;

      template<>
      struct _or_<> : false_ { };

      template<typename _T1>
      struct _or_<_T1> : _T1 { };

      template<typename _T1, typename _T2>
      struct _or_ <_T1, _T2>
        : if_<_T1, _T1, _T2> { };

      template<typename _T1, typename _T2, typename _T3, typename... _Tn>
      struct _or_<_T1, _T2, _T3, _Tn...>
         : if_<_T1, _T1, _or_<_T2, _T3, _Tn...>> { };
   }

   template <typename... _Ts>
   using or_ = eval<detail::_or_<_Ts...>>;
   //! @}

   //! AND implementation
   //! @{
   namespace detail {
      template<typename...> struct _and_;

      template<>
      struct _and_<>
         : true_ { };

      template<typename _T1>
      struct _and_ <_T1>
         : _T1 { };

      template<typename _T1, typename _T2>
      struct _and_<_T1, _T2>
         : if_<_T1, _T2, _T1> { };

      template<typename _T1, typename _T2, typename _T3, typename... _Tn>
      struct _and_<_T1, _T2, _T3, _Tn...>
         : if_<_T1, _and_<_T2, _T3, _Tn...>, _T1> { };
   }

   template <typename... _Ts>
   using and_ = eval<detail::_and_<_Ts...>>;
   //! @}

   //! same
   //! @{
   template<typename _T1, typename _T2>
   struct same_ : false_ { };

   template<typename _Tp>
   struct same_ <_Tp, _Tp> : true_ { };
   //! @}

   //! not same
   //! @{
   template<typename _T1, typename _T2>
   using not_same_ = not_<eval<same_<_T1, _T2>>>;
   //! @}

   //! @}
}}

//! @}

#endif /* __utl_meta_logical_h__ */