text: /******************************************************************************
   *                       ____    _    _____                                   *
   *                      / ___|  / \  |  ___|    C++                           *
   *                     | |     / _ \ | |_       Actor                         *
   *                     | |___ / ___ \|  _|      Framework                     *
   *                      \____/_/   \_|_|                                      *
   *                                                                            *
   * Copyright 2011-2018 Dominik Charousset                                     *
   *                                                                            *
   * Distributed under the terms and conditions of the BSD 3-Clause License or  *
   * (at your option) under the terms and conditions of the Boost Software      *
   * License 1.0. See accompanying files LICENSE and LICENSE_ALTERNATIVE.       *
   *                                                                            *
   * If you did not receive a copy of the license files, see                    *
   * http://opensource.org/licenses/BSD-3-Clause and                            *
   * http://www.boost.org/LICENSE_1_0.txt.                                      *
   ******************************************************************************/
  
  #pragma once
  
  #include <type_traits>
  
  namespace caf::detail {
  
  /// Checks whether `T` is in the template parameter pack `Ts`.
  template <class T, class... Ts>
  struct is_one_of;
  
  template <class T>
  struct is_one_of<T> : std::false_type {};
  
  template <class T, class... Ts>
  struct is_one_of<T, T, Ts...> : std::true_type {};
  
  template <class T, class U, class... Ts>
  struct is_one_of<T, U, Ts...> : is_one_of<T, Ts...> {};
  
  } // namespace caf
  
  