/*! @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