1/*!
2@file
3Adapts Boost.MPL IntegralConstants for use with Hana.
4
5Copyright Louis Dionne 2013-2022
6Distributed 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
26namespace 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
44namespace boost { namespace hana {
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}} // end namespace boost::hana
80
81#endif // !BOOST_HANA_EXT_BOOST_MPL_INTEGRAL_C_HPP
82

source code of boost/libs/hana/include/boost/hana/ext/boost/mpl/integral_c.hpp