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//
// Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail dot com)
//
// 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)
//
// Official repository: https://github.com/boostorg/beast
//
#ifndef BOOST_BEAST_DETAIL_TYPE_TRAITS_HPP
#define BOOST_BEAST_DETAIL_TYPE_TRAITS_HPP
#include <boost/type_traits/make_void.hpp>
#include <type_traits>
#include <new>
namespace boost {
namespace beast {
namespace detail {
template<class U>
std::size_t constexpr
max_sizeof()
{
return sizeof(U);
}
template<class U0, class U1, class... Us>
std::size_t constexpr
max_sizeof()
{
return
max_sizeof<U0>() > max_sizeof<U1, Us...>() ?
max_sizeof<U0>() : max_sizeof<U1, Us...>();
}
template<class U>
std::size_t constexpr
max_alignof()
{
return alignof(U);
}
template<class U0, class U1, class... Us>
std::size_t constexpr
max_alignof()
{
return
max_alignof<U0>() > max_alignof<U1, Us...>() ?
max_alignof<U0>() : max_alignof<U1, Us...>();
}
// (since C++17)
template<class... Ts>
using make_void = boost::make_void<Ts...>;
template<class... Ts>
using void_t = boost::void_t<Ts...>;
// (since C++11) missing from g++4.8
template<std::size_t Len, class... Ts>
struct aligned_union
{
static
std::size_t constexpr alignment_value =
max_alignof<Ts...>();
using type = typename std::aligned_storage<
(Len > max_sizeof<Ts...>()) ? Len : (max_sizeof<Ts...>()),
alignment_value>::type;
};
template<std::size_t Len, class... Ts>
using aligned_union_t =
typename aligned_union<Len, Ts...>::type;
//------------------------------------------------------------------------------
// for span
template<class T, class E, class = void>
struct is_contiguous_container: std::false_type {};
template<class T, class E>
struct is_contiguous_container<T, E, void_t<
decltype(
std::declval<std::size_t&>() = std::declval<T const&>().size(),
std::declval<E*&>() = std::declval<T&>().data()),
typename std::enable_if<
std::is_same<
typename std::remove_cv<E>::type,
typename std::remove_cv<
typename std::remove_pointer<
decltype(std::declval<T&>().data())
>::type
>::type
>::value
>::type>>: std::true_type
{};
template <class T, class U>
T launder_cast(U* u)
{
#if defined(__cpp_lib_launder) && __cpp_lib_launder >= 201606
return std::launder(reinterpret_cast<T>(u));
#elif defined(BOOST_GCC) && BOOST_GCC_VERSION > 80000
return __builtin_launder(reinterpret_cast<T>(u));
#else
return reinterpret_cast<T>(u);
#endif
}
} // detail
} // beast
} // boost
#endif
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