// This file is part of Bertini 2.
//
// is_template_parameter.hpp is free software: you can redistribute it and/or
// modify it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
//(at your option) any later version.
//
// is_template_parameter.hpp 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with is_template_parameter.hpp.  If not, see
// <http://www.gnu.org/licenses/>.
//
//  Copyright(C) 2015 - 2021 by Bertini2 Development Team
//
//  See <http://www.gnu.org/licenses/> for a copy of the license,
//  as well as COPYING.  Bertini2 is provided with permitted
//  additional terms in the b2/licenses/ directory.

// individual authors of this file include:
// silviana amethyst, university of wisconsin-eau claire
//

//  detail/is_template_parameter.hpp

/**
\file detail/is_template_parameter.hpp

\brief Contains the detail/is_template_parameter helper, for checking whether a
type is a template parameter in a variable template
*/

#pragma once
#include "detail/typelist.hpp"

namespace bertini {

namespace detail {

/**
Base template, which says 'no', it's not in the pack.
*/
template <typename...>
struct IsTemplateParameter {
  static constexpr bool value = false;
};

/**
Specialized template, which says 'yes', if it is in the pack, by recursively
expanding the pack.
*/
template <typename F, typename S, typename... T>
struct IsTemplateParameter<F, S, T...> {
  static constexpr bool value =
      std::is_same<F, S>::value || IsTemplateParameter<F, T...>::value;
  // either it is the same as the first one in the pack, or we need to expand to
  // the right in the pack.
};

template <typename T, typename... Ts>
struct IsTemplateParameter<T, TypeList<Ts...>> {
  static constexpr bool value = IsTemplateParameter<T, Ts...>::value;
};

}  // namespace detail

}  // namespace bertini