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- /*!
- @file
- Defines `boost::hana::replicate`.
- @copyright Louis Dionne 2013-2017
- 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
- //! @cond
- template <typename M>
- template <typename X, typename N>
- constexpr auto replicate_t<M>::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::MonadPlus<M>::value,
- "hana::replicate<M>(x, n) requires 'M' to be a MonadPlus");
- 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);
- }
- //! @endcond
- 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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