306 lines
11 KiB
C++
306 lines
11 KiB
C++
/*!
|
|
@file
|
|
Defines `boost::hana::tuple`.
|
|
|
|
@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_TUPLE_HPP
|
|
#define BOOST_HANA_TUPLE_HPP
|
|
|
|
#include <boost/hana/fwd/tuple.hpp>
|
|
|
|
#include <boost/hana/basic_tuple.hpp>
|
|
#include <boost/hana/bool.hpp>
|
|
#include <boost/hana/config.hpp>
|
|
#include <boost/hana/detail/decay.hpp>
|
|
#include <boost/hana/detail/fast_and.hpp>
|
|
#include <boost/hana/detail/index_if.hpp>
|
|
#include <boost/hana/detail/intrinsics.hpp>
|
|
#include <boost/hana/detail/operators/adl.hpp>
|
|
#include <boost/hana/detail/operators/comparable.hpp>
|
|
#include <boost/hana/detail/operators/iterable.hpp>
|
|
#include <boost/hana/detail/operators/monad.hpp>
|
|
#include <boost/hana/detail/operators/orderable.hpp>
|
|
#include <boost/hana/fwd/at.hpp>
|
|
#include <boost/hana/fwd/core/make.hpp>
|
|
#include <boost/hana/fwd/drop_front.hpp>
|
|
#include <boost/hana/fwd/find_if.hpp>
|
|
#include <boost/hana/fwd/is_empty.hpp>
|
|
#include <boost/hana/fwd/length.hpp>
|
|
#include <boost/hana/fwd/optional.hpp>
|
|
#include <boost/hana/fwd/unpack.hpp>
|
|
#include <boost/hana/type.hpp> // required by fwd decl of tuple_t
|
|
|
|
#include <cstddef>
|
|
#include <type_traits>
|
|
#include <utility>
|
|
|
|
|
|
BOOST_HANA_NAMESPACE_BEGIN
|
|
namespace detail {
|
|
template <typename Xs, typename Ys, std::size_t ...n>
|
|
constexpr void assign(Xs& xs, Ys&& ys, std::index_sequence<n...>) {
|
|
int sequence[] = {int{}, ((void)(
|
|
hana::get_impl<n>(xs) = hana::get_impl<n>(static_cast<Ys&&>(ys))
|
|
), int{})...};
|
|
(void)sequence;
|
|
}
|
|
|
|
struct from_index_sequence_t { };
|
|
}
|
|
|
|
//////////////////////////////////////////////////////////////////////////
|
|
// tuple
|
|
//////////////////////////////////////////////////////////////////////////
|
|
template <>
|
|
struct tuple<>
|
|
: detail::operators::adl<tuple<>>
|
|
, detail::iterable_operators<tuple<>>
|
|
{
|
|
constexpr tuple() { }
|
|
using hana_tag = tuple_tag;
|
|
};
|
|
|
|
template <typename ...Xn>
|
|
struct tuple
|
|
: detail::operators::adl<tuple<Xn...>>
|
|
, detail::iterable_operators<tuple<Xn...>>
|
|
{
|
|
basic_tuple<Xn...> storage_;
|
|
using hana_tag = tuple_tag;
|
|
|
|
private:
|
|
template <typename Other, std::size_t ...n>
|
|
explicit constexpr tuple(detail::from_index_sequence_t, std::index_sequence<n...>, Other&& other)
|
|
: storage_(hana::get_impl<n>(static_cast<Other&&>(other))...)
|
|
{ }
|
|
|
|
public:
|
|
template <typename ...dummy, typename = typename std::enable_if<
|
|
detail::fast_and<BOOST_HANA_TT_IS_CONSTRUCTIBLE(Xn, dummy...)...>::value
|
|
>::type>
|
|
constexpr tuple()
|
|
: storage_()
|
|
{ }
|
|
|
|
template <typename ...dummy, typename = typename std::enable_if<
|
|
detail::fast_and<BOOST_HANA_TT_IS_CONSTRUCTIBLE(Xn, Xn const&, dummy...)...>::value
|
|
>::type>
|
|
constexpr tuple(Xn const& ...xn)
|
|
: storage_(xn...)
|
|
{ }
|
|
|
|
template <typename ...Yn, typename = typename std::enable_if<
|
|
detail::fast_and<BOOST_HANA_TT_IS_CONSTRUCTIBLE(Xn, Yn&&)...>::value
|
|
>::type>
|
|
constexpr tuple(Yn&& ...yn)
|
|
: storage_(static_cast<Yn&&>(yn)...)
|
|
{ }
|
|
|
|
template <typename ...Yn, typename = typename std::enable_if<
|
|
detail::fast_and<BOOST_HANA_TT_IS_CONSTRUCTIBLE(Xn, Yn const&)...>::value
|
|
>::type>
|
|
constexpr tuple(tuple<Yn...> const& other)
|
|
: tuple(detail::from_index_sequence_t{},
|
|
std::make_index_sequence<sizeof...(Xn)>{},
|
|
other.storage_)
|
|
{ }
|
|
|
|
template <typename ...Yn, typename = typename std::enable_if<
|
|
detail::fast_and<BOOST_HANA_TT_IS_CONSTRUCTIBLE(Xn, Yn&&)...>::value
|
|
>::type>
|
|
constexpr tuple(tuple<Yn...>&& other)
|
|
: tuple(detail::from_index_sequence_t{},
|
|
std::make_index_sequence<sizeof...(Xn)>{},
|
|
static_cast<tuple<Yn...>&&>(other).storage_)
|
|
{ }
|
|
|
|
// The three following constructors are required to make sure that
|
|
// the tuple(Yn&&...) constructor is _not_ preferred over the copy
|
|
// constructor for unary tuples containing a type that is constructible
|
|
// from tuple<...>. See test/tuple/trap_construct.cpp
|
|
template <typename ...dummy, typename = typename std::enable_if<
|
|
detail::fast_and<BOOST_HANA_TT_IS_CONSTRUCTIBLE(Xn, Xn const&, dummy...)...>::value
|
|
>::type>
|
|
constexpr tuple(tuple const& other)
|
|
: tuple(detail::from_index_sequence_t{},
|
|
std::make_index_sequence<sizeof...(Xn)>{},
|
|
other.storage_)
|
|
{ }
|
|
|
|
template <typename ...dummy, typename = typename std::enable_if<
|
|
detail::fast_and<BOOST_HANA_TT_IS_CONSTRUCTIBLE(Xn, Xn const&, dummy...)...>::value
|
|
>::type>
|
|
constexpr tuple(tuple& other)
|
|
: tuple(const_cast<tuple const&>(other))
|
|
{ }
|
|
|
|
template <typename ...dummy, typename = typename std::enable_if<
|
|
detail::fast_and<BOOST_HANA_TT_IS_CONSTRUCTIBLE(Xn, Xn&&, dummy...)...>::value
|
|
>::type>
|
|
constexpr tuple(tuple&& other)
|
|
: tuple(detail::from_index_sequence_t{},
|
|
std::make_index_sequence<sizeof...(Xn)>{},
|
|
static_cast<tuple&&>(other).storage_)
|
|
{ }
|
|
|
|
|
|
template <typename ...Yn, typename = typename std::enable_if<
|
|
detail::fast_and<BOOST_HANA_TT_IS_ASSIGNABLE(Xn&, Yn const&)...>::value
|
|
>::type>
|
|
constexpr tuple& operator=(tuple<Yn...> const& other) {
|
|
detail::assign(this->storage_, other.storage_,
|
|
std::make_index_sequence<sizeof...(Xn)>{});
|
|
return *this;
|
|
}
|
|
|
|
template <typename ...Yn, typename = typename std::enable_if<
|
|
detail::fast_and<BOOST_HANA_TT_IS_ASSIGNABLE(Xn&, Yn&&)...>::value
|
|
>::type>
|
|
constexpr tuple& operator=(tuple<Yn...>&& other) {
|
|
detail::assign(this->storage_, static_cast<tuple<Yn...>&&>(other).storage_,
|
|
std::make_index_sequence<sizeof...(Xn)>{});
|
|
return *this;
|
|
}
|
|
};
|
|
|
|
//////////////////////////////////////////////////////////////////////////
|
|
// Operators
|
|
//////////////////////////////////////////////////////////////////////////
|
|
namespace detail {
|
|
template <>
|
|
struct comparable_operators<tuple_tag> {
|
|
static constexpr bool value = true;
|
|
};
|
|
template <>
|
|
struct orderable_operators<tuple_tag> {
|
|
static constexpr bool value = true;
|
|
};
|
|
template <>
|
|
struct monad_operators<tuple_tag> {
|
|
static constexpr bool value = true;
|
|
};
|
|
}
|
|
|
|
//////////////////////////////////////////////////////////////////////////
|
|
// Foldable
|
|
//////////////////////////////////////////////////////////////////////////
|
|
template <>
|
|
struct unpack_impl<tuple_tag> {
|
|
template <typename F>
|
|
static constexpr decltype(auto) apply(tuple<>&&, F&& f)
|
|
{ return static_cast<F&&>(f)(); }
|
|
template <typename F>
|
|
static constexpr decltype(auto) apply(tuple<>&, F&& f)
|
|
{ return static_cast<F&&>(f)(); }
|
|
template <typename F>
|
|
static constexpr decltype(auto) apply(tuple<> const&, F&& f)
|
|
{ return static_cast<F&&>(f)(); }
|
|
|
|
template <typename Xs, typename F>
|
|
static constexpr decltype(auto) apply(Xs&& xs, F&& f) {
|
|
return hana::unpack(static_cast<Xs&&>(xs).storage_, static_cast<F&&>(f));
|
|
}
|
|
};
|
|
|
|
template <>
|
|
struct length_impl<tuple_tag> {
|
|
template <typename ...Xs>
|
|
static constexpr auto apply(tuple<Xs...> const&)
|
|
{ return hana::size_c<sizeof...(Xs)>; }
|
|
};
|
|
|
|
//////////////////////////////////////////////////////////////////////////
|
|
// Iterable
|
|
//////////////////////////////////////////////////////////////////////////
|
|
template <>
|
|
struct at_impl<tuple_tag> {
|
|
template <typename Xs, typename N>
|
|
static constexpr decltype(auto) apply(Xs&& xs, N const&) {
|
|
constexpr std::size_t index = N::value;
|
|
return hana::get_impl<index>(static_cast<Xs&&>(xs).storage_);
|
|
}
|
|
};
|
|
|
|
template <>
|
|
struct drop_front_impl<tuple_tag> {
|
|
template <std::size_t N, typename Xs, std::size_t ...i>
|
|
static constexpr auto helper(Xs&& xs, std::index_sequence<i...>) {
|
|
return hana::make<tuple_tag>(hana::at_c<i+N>(static_cast<Xs&&>(xs))...);
|
|
}
|
|
|
|
template <typename Xs, typename N>
|
|
static constexpr auto apply(Xs&& xs, N const&) {
|
|
constexpr std::size_t len = decltype(hana::length(xs))::value;
|
|
return helper<N::value>(static_cast<Xs&&>(xs), std::make_index_sequence<
|
|
N::value < len ? len - N::value : 0
|
|
>{});
|
|
}
|
|
};
|
|
|
|
template <>
|
|
struct is_empty_impl<tuple_tag> {
|
|
template <typename ...Xs>
|
|
static constexpr auto apply(tuple<Xs...> const&)
|
|
{ return hana::bool_c<sizeof...(Xs) == 0>; }
|
|
};
|
|
|
|
// compile-time optimizations (to reduce the # of function instantiations)
|
|
template <std::size_t n, typename ...Xs>
|
|
constexpr decltype(auto) at_c(tuple<Xs...> const& xs) {
|
|
return hana::get_impl<n>(xs.storage_);
|
|
}
|
|
|
|
template <std::size_t n, typename ...Xs>
|
|
constexpr decltype(auto) at_c(tuple<Xs...>& xs) {
|
|
return hana::get_impl<n>(xs.storage_);
|
|
}
|
|
|
|
template <std::size_t n, typename ...Xs>
|
|
constexpr decltype(auto) at_c(tuple<Xs...>&& xs) {
|
|
return hana::get_impl<n>(static_cast<tuple<Xs...>&&>(xs).storage_);
|
|
}
|
|
|
|
//////////////////////////////////////////////////////////////////////////
|
|
// Sequence
|
|
//////////////////////////////////////////////////////////////////////////
|
|
template <>
|
|
struct Sequence<tuple_tag> {
|
|
static constexpr bool value = true;
|
|
};
|
|
|
|
template <>
|
|
struct make_impl<tuple_tag> {
|
|
template <typename ...Xs>
|
|
static constexpr
|
|
tuple<typename detail::decay<Xs>::type...> apply(Xs&& ...xs)
|
|
{ return {static_cast<Xs&&>(xs)...}; }
|
|
};
|
|
|
|
template <>
|
|
struct find_if_impl<tuple_tag> {
|
|
template <std::size_t index, typename Xs>
|
|
static constexpr auto helper(Xs&&, hana::true_) {
|
|
return hana::nothing;
|
|
}
|
|
|
|
template <std::size_t index, typename Xs>
|
|
static constexpr auto helper(Xs&& xs, hana::false_) {
|
|
return hana::just(hana::at_c<index>(static_cast<Xs&&>(xs)));
|
|
}
|
|
|
|
template <typename Xs, typename Pred>
|
|
static constexpr auto apply(Xs&& xs, Pred&&) {
|
|
using Pack = typename detail::make_pack<Xs>::type;
|
|
constexpr std::size_t index = detail::index_if<Pred&&, Pack>::value;
|
|
constexpr std::size_t len = Pack::length;
|
|
return helper<index>(static_cast<Xs&&>(xs), hana::bool_c<index == len>);
|
|
}
|
|
};
|
|
BOOST_HANA_NAMESPACE_END
|
|
|
|
#endif // !BOOST_HANA_TUPLE_HPP
|