ceph/src/boost/libs/hana/include/boost/hana/ext/boost/mpl/integral_c.hpp

   1 /*!
   2 @file
   3 Adapts Boost.MPL IntegralConstants for use with Hana.
   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_EXT_BOOST_MPL_INTEGRAL_C_HPP
  11 #define BOOST_HANA_EXT_BOOST_MPL_INTEGRAL_C_HPP
  12
  13 #include <boost/hana/concept/integral_constant.hpp>
  14 #include <boost/hana/config.hpp>
  15 #include <boost/hana/core/tag_of.hpp>
  16 #include <boost/hana/core/when.hpp>
  17 #include <boost/hana/fwd/core/to.hpp>
  18
  19 #include <boost/mpl/integral_c.hpp>
  20 #include <boost/mpl/integral_c_tag.hpp>
  21
  22 #include <type_traits>
  23
  24
  25 #ifdef BOOST_HANA_DOXYGEN_INVOKED
  26 namespace boost { namespace mpl {
  27     //! @ingroup group-ext-mpl
  28     //! Adapter for IntegralConstants from the Boost.MPL.
  29     //!
  30     //! Provided models
  31     //! ---------------
  32     //! 1. `Constant` and `IntegralConstant`\n
  33     //! A Boost.MPL IntegralConstant is a model of the `IntegralConstant`
  34     //! and `Constant` concepts just like `hana::integral_constant`s are.
  35     //! As a consequence, they are also implicitly a model of the concepts
  36     //! provided for all models of `Constant`.
  37     //! @include example/ext/boost/mpl/integral_c/integral_constant.cpp
  38     template <typename T, T v>
  39     struct integral_c { };
  40 }}
  41 #endif
  42
  43
  44 BOOST_HANA_NAMESPACE_BEGIN
  45     namespace ext { namespace boost { namespace mpl {
  46         template <typename T>
  47         struct integral_c_tag { using value_type = T; };
  48     }}}
  49
  50     template <typename T>
  51     struct tag_of<T, when<
  52         std::is_same<
  53             typename T::tag,
  54             ::boost::mpl::integral_c_tag
  55         >::value
  56     >> {
  57         using type = ext::boost::mpl::integral_c_tag<
  58             typename hana::tag_of<typename T::value_type>::type
  59         >;
  60     };
  61
  62     //////////////////////////////////////////////////////////////////////////
  63     // IntegralConstant/Constant
  64     //////////////////////////////////////////////////////////////////////////
  65     template <typename T>
  66     struct IntegralConstant<ext::boost::mpl::integral_c_tag<T>> {
  67         static constexpr bool value = true;
  68     };
  69
  70     template <typename T, typename C>
  71     struct to_impl<ext::boost::mpl::integral_c_tag<T>, C,
  72         when<hana::IntegralConstant<C>::value>
  73     > : embedding<is_embedded<typename C::value_type, T>::value> {
  74         template <typename N>
  75         static constexpr auto apply(N const&) {
  76             return ::boost::mpl::integral_c<T, N::value>{};
  77         }
  78     };
  79 BOOST_HANA_NAMESPACE_END
  80
  81 #endif // !BOOST_HANA_EXT_BOOST_MPL_INTEGRAL_C_HPP