/*!
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@file
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Adapts Boost.MPL IntegralConstants for use with Hana.
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@copyright Louis Dionne 2013-2017
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
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*/
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#ifndef BOOST_HANA_EXT_BOOST_MPL_INTEGRAL_C_HPP
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#define BOOST_HANA_EXT_BOOST_MPL_INTEGRAL_C_HPP
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#include <boost/hana/concept/integral_constant.hpp>
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#include <boost/hana/config.hpp>
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#include <boost/hana/core/tag_of.hpp>
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#include <boost/hana/core/when.hpp>
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#include <boost/hana/fwd/core/to.hpp>
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#include <boost/mpl/integral_c.hpp>
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#include <boost/mpl/integral_c_tag.hpp>
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#include <type_traits>
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#ifdef BOOST_HANA_DOXYGEN_INVOKED
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namespace boost { namespace mpl {
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//! @ingroup group-ext-mpl
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//! Adapter for IntegralConstants from the Boost.MPL.
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//!
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//! Provided models
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//! ---------------
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//! 1. `Constant` and `IntegralConstant`\n
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//! A Boost.MPL IntegralConstant is a model of the `IntegralConstant`
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//! and `Constant` concepts just like `hana::integral_constant`s are.
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//! As a consequence, they are also implicitly a model of the concepts
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//! provided for all models of `Constant`.
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//! @include example/ext/boost/mpl/integral_c/integral_constant.cpp
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template <typename T, T v>
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struct integral_c { };
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}}
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#endif
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BOOST_HANA_NAMESPACE_BEGIN
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namespace ext { namespace boost { namespace mpl {
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template <typename T>
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struct integral_c_tag { using value_type = T; };
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}}}
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template <typename T>
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struct tag_of<T, when<
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std::is_same<
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typename T::tag,
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::boost::mpl::integral_c_tag
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>::value
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>> {
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using type = ext::boost::mpl::integral_c_tag<
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typename hana::tag_of<typename T::value_type>::type
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>;
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};
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//////////////////////////////////////////////////////////////////////////
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// IntegralConstant/Constant
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//////////////////////////////////////////////////////////////////////////
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template <typename T>
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struct IntegralConstant<ext::boost::mpl::integral_c_tag<T>> {
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static constexpr bool value = true;
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};
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template <typename T, typename C>
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struct to_impl<ext::boost::mpl::integral_c_tag<T>, C,
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when<hana::IntegralConstant<C>::value>
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> : embedding<is_embedded<typename C::value_type, T>::value> {
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template <typename N>
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static constexpr auto apply(N const&) {
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return ::boost::mpl::integral_c<T, N::value>{};
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}
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};
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BOOST_HANA_NAMESPACE_END
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#endif // !BOOST_HANA_EXT_BOOST_MPL_INTEGRAL_C_HPP
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