131 lines
3.6 KiB
C++
131 lines
3.6 KiB
C++
/*=============================================================================
|
|
Copyright (c) 2015 Paul Fultz II
|
|
compressed_pair.h
|
|
Distributed under the Boost Software License, Version 1.0. (See accompanying
|
|
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
|
|
==============================================================================*/
|
|
|
|
#ifndef BOOST_HOF_GUARD_COMPRESSED_PAIR_H
|
|
#define BOOST_HOF_GUARD_COMPRESSED_PAIR_H
|
|
|
|
#include <boost/hof/detail/delegate.hpp>
|
|
#include <boost/hof/detail/move.hpp>
|
|
#include <boost/hof/detail/forward.hpp>
|
|
#include <boost/hof/config.hpp>
|
|
#include <boost/hof/always.hpp>
|
|
#include <boost/hof/alias.hpp>
|
|
|
|
#ifndef BOOST_HOF_COMPRESSED_PAIR_USE_EBO_WORKAROUND
|
|
#define BOOST_HOF_COMPRESSED_PAIR_USE_EBO_WORKAROUND !BOOST_HOF_HAS_EBO
|
|
#endif
|
|
|
|
namespace boost { namespace hof { namespace detail {
|
|
|
|
template<class First, class Second, class=void>
|
|
struct compressed_pair;
|
|
|
|
template<int I, class T, class U>
|
|
struct pair_tag
|
|
{};
|
|
|
|
#if BOOST_HOF_COMPRESSED_PAIR_USE_EBO_WORKAROUND
|
|
|
|
template<class T, class U>
|
|
struct is_same_template
|
|
: std::false_type
|
|
{};
|
|
|
|
template<template<class...> class X, class... Ts, class... Us>
|
|
struct is_same_template<X<Ts...>, X<Us...>>
|
|
: std::true_type
|
|
{};
|
|
|
|
#if (defined(__GNUC__) && !defined (__clang__) && __GNUC__ == 4 && __GNUC_MINOR__ < 7)
|
|
|
|
template<class T, class U>
|
|
struct is_related_template
|
|
: std::false_type
|
|
{};
|
|
|
|
#else
|
|
|
|
template<class T, class U>
|
|
struct is_related_template
|
|
: is_same_template<T, U>
|
|
{};
|
|
|
|
#endif
|
|
|
|
template<class T, class U>
|
|
struct is_related
|
|
: std::integral_constant<bool, std::is_base_of<T, U>::value || std::is_base_of<U, T>::value || is_related_template<T, U>::value>
|
|
{};
|
|
|
|
template<int I, class T, class U>
|
|
struct pair_holder
|
|
: std::conditional<(
|
|
is_related<T, U>::value),
|
|
detail::alias_empty<T, pair_tag<I, T, U>>,
|
|
detail::alias_try_inherit<T, pair_tag<I, T, U>>
|
|
>::type
|
|
{};
|
|
#else
|
|
template<int I, class T, class U>
|
|
struct pair_holder
|
|
: detail::alias_try_inherit<T, pair_tag<I, T, U>>
|
|
{};
|
|
#endif
|
|
|
|
// TODO: Empty optimizations for MSVC
|
|
template<
|
|
class First,
|
|
class Second
|
|
>
|
|
struct compressed_pair<First, Second>
|
|
: pair_holder<0, First, Second>::type, pair_holder<1, Second, First>::type
|
|
{
|
|
typedef typename pair_holder<0, First, Second>::type first_base;
|
|
typedef typename pair_holder<1, Second, First>::type second_base;
|
|
template<class X, class Y,
|
|
BOOST_HOF_ENABLE_IF_CONSTRUCTIBLE(First, X&&),
|
|
BOOST_HOF_ENABLE_IF_CONSTRUCTIBLE(Second, Y&&)
|
|
>
|
|
constexpr compressed_pair(X&& x, Y&& y)
|
|
noexcept(BOOST_HOF_IS_NOTHROW_CONSTRUCTIBLE(first_base, X&&) && BOOST_HOF_IS_NOTHROW_CONSTRUCTIBLE(second_base, Y&&))
|
|
: first_base(BOOST_HOF_FORWARD(X)(x)), second_base(BOOST_HOF_FORWARD(Y)(y))
|
|
{}
|
|
|
|
BOOST_HOF_INHERIT_DEFAULT(compressed_pair, first_base, second_base)
|
|
|
|
template<class Base, class... Xs>
|
|
constexpr const Base& get_alias_base(Xs&&... xs) const noexcept
|
|
{
|
|
return boost::hof::always_ref(*this)(xs...);
|
|
}
|
|
|
|
template<class... Xs>
|
|
constexpr const First& first(Xs&&... xs) const noexcept
|
|
{
|
|
return boost::hof::alias_value(this->get_alias_base<first_base>(xs...), xs...);
|
|
}
|
|
|
|
template<class... Xs>
|
|
constexpr const Second& second(Xs&&... xs) const noexcept
|
|
{
|
|
return boost::hof::alias_value(this->get_alias_base<second_base>(xs...), xs...);
|
|
}
|
|
|
|
};
|
|
|
|
template<class T, class U>
|
|
constexpr compressed_pair<T, U> make_compressed_pair(T x, U y)
|
|
noexcept(BOOST_HOF_IS_NOTHROW_MOVE_CONSTRUCTIBLE(T) && BOOST_HOF_IS_NOTHROW_MOVE_CONSTRUCTIBLE(U))
|
|
{
|
|
return {static_cast<T&&>(x), static_cast<U&&>(y)};
|
|
}
|
|
|
|
|
|
}}} // namespace boost::hof
|
|
|
|
#endif
|