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+/*!
+@file
+Defines `boost::hana::lift`.
+
+@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_LIFT_HPP
+#define BOOST_HANA_LIFT_HPP
+
+#include <boost/hana/fwd/lift.hpp>
+
+#include <boost/hana/concept/applicative.hpp>
+#include <boost/hana/concept/sequence.hpp>
+#include <boost/hana/config.hpp>
+#include <boost/hana/core/dispatch.hpp>
+#include <boost/hana/core/make.hpp>
+
+
+BOOST_HANA_NAMESPACE_BEGIN
+ template <typename A>
+ struct lift_t {
+ #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
+ static_assert(hana::Applicative<A>::value,
+ "hana::lift<A> requires 'A' to be an Applicative");
+ #endif
+
+ template <typename X>
+ constexpr auto operator()(X&& x) const {
+ using Lift = BOOST_HANA_DISPATCH_IF(lift_impl<A>,
+ hana::Applicative<A>::value
+ );
+
+ return Lift::apply(static_cast<X&&>(x));
+ }
+ };
+
+ template <typename A, bool condition>
+ struct lift_impl<A, when<condition>> : default_ {
+ template <typename ...Args>
+ static constexpr auto apply(Args&& ...args) = delete;
+ };
+
+ template <typename S>
+ struct lift_impl<S, when<Sequence<S>::value>> {
+ template <typename X>
+ static constexpr decltype(auto) apply(X&& x)
+ { return hana::make<S>(static_cast<X&&>(x)); }
+ };
+BOOST_HANA_NAMESPACE_END
+
+#endif // !BOOST_HANA_LIFT_HPP