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

   1 /*!
   2 @file
   3 Defines `boost::hana::Foldable`.
   4
   5 @copyright Louis Dionne 2013-2017
   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/detail/integral_constant.hpp>
  19 #include <boost/hana/fold_left.hpp>
  20 #include <boost/hana/unpack.hpp>
  21
  22
  23 namespace boost { namespace hana {
  24     template <typename T>
  25     struct Foldable
  26         : hana::integral_constant<bool,
  27             !is_default<fold_left_impl<typename tag_of<T>::type>>::value ||
  28             !is_default<unpack_impl<typename tag_of<T>::type>>::value
  29         >
  30     { };
  31 }} // end namespace boost::hana
  32
  33 #endif // !BOOST_HANA_CONCEPT_FOLDABLE_HPP