75 lines
2.4 KiB
C++
75 lines
2.4 KiB
C++
|
/*!
|
||
|
|
@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
|