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/*!
@file
Defines `boost::hana::make`.
@copyright Louis Dionne 2013-2016
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
*/
#ifndef BOOST_HANA_CORE_MAKE_HPP
#define BOOST_HANA_CORE_MAKE_HPP
#include <boost/hana/fwd/core/make.hpp>
#include <boost/hana/config.hpp>
#include <boost/hana/core/default.hpp>
#include <boost/hana/core/when.hpp>
BOOST_HANA_NAMESPACE_BEGIN
//! @cond
template <typename Datatype, typename>
struct make_impl : make_impl<Datatype, when<true>> { };
//! @endcond
template <typename Datatype, bool condition>
struct make_impl<Datatype, when<condition>> : default_ {
template <typename ...X>
static constexpr auto make_helper(int, X&& ...x)
-> decltype(Datatype(static_cast<X&&>(x)...))
{ return Datatype(static_cast<X&&>(x)...); }
template <typename ...X>
static constexpr auto make_helper(long, X&& ...) {
static_assert((sizeof...(X), false),
"there exists no constructor for the given data type");
}
template <typename ...X>
static constexpr decltype(auto) apply(X&& ...x)
{ return make_helper(int{}, static_cast<X&&>(x)...); }
};
BOOST_HANA_NAMESPACE_END
#endif // !BOOST_HANA_CORE_MAKE_HPP
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