ceph/src/boost/libs/hana/include/boost/hana/detail/operators/monad.hpp

   1 /*!
   2 @file
   3 Defines operators for Monads.
   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_DETAIL_OPERATORS_MONAD_HPP
  11 #define BOOST_HANA_DETAIL_OPERATORS_MONAD_HPP
  12
  13 #include <boost/hana/config.hpp>
  14 #include <boost/hana/core/tag_of.hpp>
  15 #include <boost/hana/fwd/chain.hpp>
  16
  17 #include <type_traits>
  18
  19
  20 BOOST_HANA_NAMESPACE_BEGIN namespace detail {
  21     template <typename Tag>
  22     struct monad_operators {
  23         static constexpr bool value = false;
  24     };
  25
  26     namespace operators {
  27         template <typename Xs, typename F, typename = typename std::enable_if<
  28             detail::monad_operators<typename hana::tag_of<Xs>::type>::value
  29         >::type>
  30         constexpr auto operator|(Xs&& xs, F&& f)
  31         { return hana::chain(static_cast<Xs&&>(xs), static_cast<F&&>(f)); }
  32     } // end namespace operators
  33 } BOOST_HANA_NAMESPACE_END
  34
  35 #endif // !BOOST_HANA_DETAIL_OPERATORS_MONAD_HPP