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/*!
@file
Defines `boost::hana::basic_tuple`.
@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_BASIC_TUPLE_HPP
#define BOOST_HANA_BASIC_TUPLE_HPP
#include <boost/hana/fwd/basic_tuple.hpp>
#include <boost/hana/config.hpp>
#include <boost/hana/detail/decay.hpp>
#include <boost/hana/detail/ebo.hpp>
#include <boost/hana/fwd/at.hpp>
#include <boost/hana/fwd/bool.hpp>
#include <boost/hana/fwd/concept/sequence.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/fwd/integral_constant.hpp>
#include <boost/hana/fwd/is_empty.hpp>
#include <boost/hana/fwd/length.hpp>
#include <boost/hana/fwd/transform.hpp>
#include <boost/hana/fwd/unpack.hpp>
#include <cstddef>
#include <type_traits>
#include <utility>
BOOST_HANA_NAMESPACE_BEGIN
namespace detail {
//////////////////////////////////////////////////////////////////////
// basic_tuple_impl<n, Xn>
//////////////////////////////////////////////////////////////////////
template <std::size_t> struct bti; // basic_tuple_index
struct from_other { };
template <typename Indices, typename ...Xn>
struct basic_tuple_impl;
template <std::size_t ...n, typename ...Xn>
struct basic_tuple_impl<std::index_sequence<n...>, Xn...>
: detail::ebo<bti<n>, Xn>...
{
static constexpr std::size_t size_ = sizeof...(Xn);
constexpr basic_tuple_impl() = default;
template <typename Other>
explicit constexpr basic_tuple_impl(detail::from_other, Other&& other)
: detail::ebo<bti<n>, Xn>(detail::ebo_get<bti<n>>(static_cast<Other&&>(other)))...
{ }
template <typename ...Yn>
explicit constexpr basic_tuple_impl(Yn&& ...yn)
: detail::ebo<bti<n>, Xn>(static_cast<Yn&&>(yn))...
{ }
};
}
//////////////////////////////////////////////////////////////////////////
// basic_tuple
//////////////////////////////////////////////////////////////////////////
//! @cond
template <typename ...Xn>
struct basic_tuple final
: detail::basic_tuple_impl<std::make_index_sequence<sizeof...(Xn)>, Xn...>
{
using Base = detail::basic_tuple_impl<std::make_index_sequence<sizeof...(Xn)>, Xn...>;
constexpr basic_tuple() = default;
// copy constructor
template <typename Other, typename = typename std::enable_if<
std::is_same<typename detail::decay<Other>::type, basic_tuple>::value
>::type>
constexpr basic_tuple(Other&& other)
: Base(detail::from_other{}, static_cast<Other&&>(other))
{ }
template <typename ...Yn>
explicit constexpr basic_tuple(Yn&& ...yn)
: Base(static_cast<Yn&&>(yn)...)
{ }
};
//! @endcond
template <typename ...Xn>
struct tag_of<basic_tuple<Xn...>> {
using type = basic_tuple_tag;
};
//////////////////////////////////////////////////////////////////////////
// Foldable
//////////////////////////////////////////////////////////////////////////
template <>
struct unpack_impl<basic_tuple_tag> {
template <std::size_t ...i, typename ...Xn, typename F>
static constexpr decltype(auto)
apply(detail::basic_tuple_impl<std::index_sequence<i...>, Xn...> const& xs, F&& f) {
return static_cast<F&&>(f)(
detail::ebo_get<detail::bti<i>>(
static_cast<detail::ebo<detail::bti<i>, Xn> const&>(xs)
)...
);
}
template <std::size_t ...i, typename ...Xn, typename F>
static constexpr decltype(auto)
apply(detail::basic_tuple_impl<std::index_sequence<i...>, Xn...>& xs, F&& f) {
return static_cast<F&&>(f)(
detail::ebo_get<detail::bti<i>>(
static_cast<detail::ebo<detail::bti<i>, Xn>&>(xs)
)...
);
}
template <std::size_t ...i, typename ...Xn, typename F>
static constexpr decltype(auto)
apply(detail::basic_tuple_impl<std::index_sequence<i...>, Xn...>&& xs, F&& f) {
return static_cast<F&&>(f)(
detail::ebo_get<detail::bti<i>>(
static_cast<detail::ebo<detail::bti<i>, Xn>&&>(xs)
)...
);
}
};
//////////////////////////////////////////////////////////////////////////
// Functor
//////////////////////////////////////////////////////////////////////////
template <>
struct transform_impl<basic_tuple_tag> {
template <std::size_t ...i, typename ...Xn, typename F>
static constexpr auto
apply(detail::basic_tuple_impl<std::index_sequence<i...>, Xn...> const& xs, F const& f) {
return hana::make_basic_tuple(
f(detail::ebo_get<detail::bti<i>>(
static_cast<detail::ebo<detail::bti<i>, Xn> const&>(xs)
))...
);
}
template <std::size_t ...i, typename ...Xn, typename F>
static constexpr auto
apply(detail::basic_tuple_impl<std::index_sequence<i...>, Xn...>& xs, F const& f) {
return hana::make_basic_tuple(
f(detail::ebo_get<detail::bti<i>>(
static_cast<detail::ebo<detail::bti<i>, Xn>&>(xs)
))...
);
}
template <std::size_t ...i, typename ...Xn, typename F>
static constexpr auto
apply(detail::basic_tuple_impl<std::index_sequence<i...>, Xn...>&& xs, F const& f) {
return hana::make_basic_tuple(
f(detail::ebo_get<detail::bti<i>>(
static_cast<detail::ebo<detail::bti<i>, Xn>&&>(xs)
))...
);
}
};
//////////////////////////////////////////////////////////////////////////
// Iterable
//////////////////////////////////////////////////////////////////////////
template <>
struct at_impl<basic_tuple_tag> {
template <typename Xs, typename N>
static constexpr decltype(auto) apply(Xs&& xs, N const&) {
constexpr std::size_t index = N::value;
return detail::ebo_get<detail::bti<index>>(static_cast<Xs&&>(xs));
}
};
template <>
struct drop_front_impl<basic_tuple_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_basic_tuple(
detail::ebo_get<detail::bti<i+N>>(static_cast<Xs&&>(xs))...
);
}
template <typename Xs, typename N>
static constexpr auto apply(Xs&& xs, N const&) {
constexpr std::size_t len = detail::decay<Xs>::type::size_;
return drop_front_helper<N::value>(static_cast<Xs&&>(xs), std::make_index_sequence<
N::value < len ? len - N::value : 0
>{});
}
};
template <>
struct is_empty_impl<basic_tuple_tag> {
template <typename ...Xs>
static constexpr hana::bool_<sizeof...(Xs) == 0>
apply(basic_tuple<Xs...> const&)
{ return {}; }
};
// compile-time optimizations (to reduce the # of function instantiations)
template <std::size_t n, typename ...Xs>
constexpr decltype(auto) at_c(basic_tuple<Xs...> const& xs) {
return detail::ebo_get<detail::bti<n>>(xs);
}
template <std::size_t n, typename ...Xs>
constexpr decltype(auto) at_c(basic_tuple<Xs...>& xs) {
return detail::ebo_get<detail::bti<n>>(xs);
}
template <std::size_t n, typename ...Xs>
constexpr decltype(auto) at_c(basic_tuple<Xs...>&& xs) {
return detail::ebo_get<detail::bti<n>>(static_cast<basic_tuple<Xs...>&&>(xs));
}
//////////////////////////////////////////////////////////////////////////
// Sequence
//////////////////////////////////////////////////////////////////////////
template <>
struct Sequence<basic_tuple_tag> {
static constexpr bool value = true;
};
template <>
struct make_impl<basic_tuple_tag> {
template <typename ...Xn>
static constexpr basic_tuple<typename detail::decay<Xn>::type...>
apply(Xn&& ...xn) {
return basic_tuple<typename detail::decay<Xn>::type...>{
static_cast<Xn&&>(xn)...
};
}
};
//////////////////////////////////////////////////////////////////////////
// length
//////////////////////////////////////////////////////////////////////////
template <>
struct length_impl<basic_tuple_tag> {
template <typename ...Xn>
static constexpr auto apply(basic_tuple<Xn...> const&) {
return hana::size_t<sizeof...(Xn)>{};
}
};
BOOST_HANA_NAMESPACE_END
#endif // !BOOST_HANA_BASIC_TUPLE_HPP
|
