ceph/src/boost/libs/hana/include/boost/hana/concept/foldable.hpp

   1 /*!
   2 @file
   3 Defines `boost::hana::Foldable`.
   4
   5 @copyright Louis Dionne 2013-2016
   6 Distributed under the Boost Software License, Version 1.0.
   7 (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
   8  */
   9
  10 #ifndef BOOST_HANA_CONCEPT_FOLDABLE_HPP
  11 #define BOOST_HANA_CONCEPT_FOLDABLE_HPP
  12
  13 #include <boost/hana/fwd/concept/foldable.hpp>
  14
  15 #include <boost/hana/config.hpp>
  16 #include <boost/hana/core/default.hpp>
  17 #include <boost/hana/core/tag_of.hpp>
  18 #include <boost/hana/fold_left.hpp>
  19 #include <boost/hana/unpack.hpp>
  20
  21
  22 BOOST_HANA_NAMESPACE_BEGIN
  23     template <typename T>
  24     struct Foldable {
  25         using Tag = typename tag_of<T>::type;
  26         static constexpr bool value = !is_default<fold_left_impl<Tag>>::value ||
  27                                       !is_default<unpack_impl<Tag>>::value;
  28     };
  29 BOOST_HANA_NAMESPACE_END
  30
  31 #endif // !BOOST_HANA_CONCEPT_FOLDABLE_HPP