boost/hana/detail/nested_by.hpp

   1 /*!
   2 @file
   3 Defines `boost::hana::detail::nested_by`.
   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_DETAIL_NESTED_BY_HPP
  11 #define BOOST_HANA_DETAIL_NESTED_BY_HPP
  12
  13 #include <boost/hana/config.hpp>
  14 #include <boost/hana/detail/nested_by_fwd.hpp>
  15
  16 #include <boost/hana/functional/flip.hpp>
  17 #include <boost/hana/functional/partial.hpp>
  18
  19
  20 BOOST_HANA_NAMESPACE_BEGIN namespace detail {
  21     //! @cond
  22     template <typename Algorithm>
  23     template <typename Predicate, typename Object>
  24     constexpr decltype(auto) nested_by_t<Algorithm>::
  25     operator()(Predicate&& predicate, Object&& object) const {
  26         return Algorithm{}(static_cast<Object&&>(object),
  27                            static_cast<Predicate&&>(predicate));
  28     }
  29
  30     template <typename Algorithm>
  31     template <typename Predicate>
  32     constexpr decltype(auto)
  33     nested_by_t<Algorithm>::operator()(Predicate&& predicate) const {
  34         return hana::partial(hana::flip(Algorithm{}),
  35                              static_cast<Predicate&&>(predicate));
  36     }
  37     //! @endcond
  38 } BOOST_HANA_NAMESPACE_END
  39
  40 #endif // !BOOST_HANA_DETAIL_NESTED_BY_HPP