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/*!
@file
Defines `boost::hana::replicate`.
@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_REPLICATE_HPP
#define BOOST_HANA_REPLICATE_HPP
#include <boost/hana/fwd/replicate.hpp>
#include <boost/hana/concept/integral_constant.hpp>
#include <boost/hana/concept/monad_plus.hpp>
#include <boost/hana/config.hpp>
#include <boost/hana/core/dispatch.hpp>
#include <boost/hana/core/make.hpp>
#include <boost/hana/cycle.hpp>
#include <boost/hana/lift.hpp>
#include <cstddef>
#include <utility>
BOOST_HANA_NAMESPACE_BEGIN
template <typename M>
struct replicate_t {
#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
static_assert(hana::MonadPlus<M>::value,
"hana::replicate<M>(x, n) requires 'M' to be a MonadPlus");
#endif
template <typename X, typename N>
constexpr auto operator()(X&& x, N const& n) const {
using Replicate = BOOST_HANA_DISPATCH_IF(replicate_impl<M>,
hana::MonadPlus<M>::value &&
hana::IntegralConstant<N>::value
);
#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
static_assert(hana::IntegralConstant<N>::value,
"hana::replicate<M>(x, n) requires 'n' to be an IntegralConstant");
#endif
return Replicate::apply(static_cast<X&&>(x), n);
}
};
template <typename M, bool condition>
struct replicate_impl<M, when<condition>> : default_ {
template <typename X, typename N>
static constexpr auto apply(X&& x, N const& n) {
return hana::cycle(hana::lift<M>(static_cast<X&&>(x)), n);
}
};
template <typename S>
struct replicate_impl<S, when<Sequence<S>::value>> {
template <typename X, std::size_t ...i>
static constexpr auto replicate_helper(X&& x, std::index_sequence<i...>)
{ return hana::make<S>(((void)i, x)...); }
template <typename X, typename N>
static constexpr auto apply(X&& x, N const&) {
constexpr std::size_t n = N::value;
return replicate_helper(static_cast<X&&>(x),
std::make_index_sequence<n>{});
}
};
BOOST_HANA_NAMESPACE_END
#endif // !BOOST_HANA_REPLICATE_HPP
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