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/*!
@file
Adapts `boost::fusion::deque` for use with Hana.
@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_EXT_BOOST_FUSION_DEQUE_HPP
#define BOOST_HANA_EXT_BOOST_FUSION_DEQUE_HPP
#include <boost/hana/at.hpp>
#include <boost/hana/core/when.hpp>
#include <boost/hana/config.hpp>
#include <boost/hana/ext/boost/fusion/detail/common.hpp>
#include <boost/hana/fwd/core/make.hpp>
#include <boost/hana/fwd/core/tag_of.hpp>
#include <boost/hana/fwd/drop_front.hpp>
#include <boost/hana/length.hpp>
#include <boost/fusion/container/deque.hpp>
#include <boost/fusion/container/generation/make_deque.hpp>
#include <boost/fusion/support/tag_of.hpp>
#include <cstddef>
#include <type_traits>
#include <utility>
#ifdef BOOST_HANA_DOXYGEN_INVOKED
namespace boost { namespace fusion {
//! @ingroup group-ext-fusion
//! Adapter for Boost.Fusion deques.
//!
//!
//! Modeled concepts
//! ----------------
//! A Fusion deque is a model of the `Sequence` concept, and all the
//! concepts it refines. That makes it essentially the same as a Hana
//! tuple, although the complexity of some operations might differ from
//! that of a tuple.
//!
//! @include example/ext/boost/fusion/deque.cpp
template <typename ...T>
struct deque { };
}}
#endif
BOOST_HANA_NAMESPACE_BEGIN
namespace ext { namespace boost { namespace fusion {
struct deque_tag;
}}}
template <typename T>
struct tag_of<T, when<
std::is_same<
typename ::boost::fusion::traits::tag_of<T>::type,
::boost::fusion::traits::tag_of<
::boost::fusion::deque<>
>::type
>::value
>> {
using type = ext::boost::fusion::deque_tag;
};
namespace detail {
template <>
struct is_fusion_sequence<ext::boost::fusion::deque_tag> {
static constexpr bool value = true;
};
}
//////////////////////////////////////////////////////////////////////////
// Iterable (the rest is in detail/common.hpp)
//////////////////////////////////////////////////////////////////////////
template <>
struct drop_front_impl<ext::boost::fusion::deque_tag> {
template <std::size_t n, typename Xs, std::size_t ...i>
static constexpr auto drop_front_helper(Xs&& xs, std::index_sequence<i...>) {
return hana::make<ext::boost::fusion::deque_tag>(
hana::at_c<n + i>(static_cast<Xs&&>(xs))...
);
}
template <typename Xs, typename N>
static constexpr auto apply(Xs&& xs, N const&) {
constexpr std::size_t n = N::value;
constexpr std::size_t len = decltype(hana::length(xs))::value;
return drop_front_helper<n>(static_cast<Xs&&>(xs),
std::make_index_sequence<(n < len ? len - n : 0)>{});
}
};
//////////////////////////////////////////////////////////////////////////
// Sequence
//////////////////////////////////////////////////////////////////////////
template <>
struct make_impl<ext::boost::fusion::deque_tag> {
template <typename ...Xs>
static constexpr auto apply(Xs&& ...xs) {
return ::boost::fusion::make_deque(static_cast<Xs&&>(xs)...);
}
};
BOOST_HANA_NAMESPACE_END
#endif // !BOOST_HANA_EXT_BOOST_FUSION_DEQUE_HPP
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