//
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// Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail dot com)
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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// Official repository: https://github.com/boostorg/beast
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//
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#ifndef BOOST_BEAST_DETAIL_TYPE_TRAITS_HPP
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#define BOOST_BEAST_DETAIL_TYPE_TRAITS_HPP
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#include <boost/type_traits/make_void.hpp>
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#include <type_traits>
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#include <new>
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namespace boost {
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namespace beast {
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namespace detail {
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template<class U>
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std::size_t constexpr
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max_sizeof()
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{
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return sizeof(U);
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}
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template<class U0, class U1, class... Us>
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std::size_t constexpr
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max_sizeof()
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{
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return
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max_sizeof<U0>() > max_sizeof<U1, Us...>() ?
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max_sizeof<U0>() : max_sizeof<U1, Us...>();
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}
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template<class U>
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std::size_t constexpr
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max_alignof()
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{
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return alignof(U);
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}
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template<class U0, class U1, class... Us>
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std::size_t constexpr
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max_alignof()
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{
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return
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max_alignof<U0>() > max_alignof<U1, Us...>() ?
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max_alignof<U0>() : max_alignof<U1, Us...>();
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}
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// (since C++17)
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template<class... Ts>
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using make_void = boost::make_void<Ts...>;
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template<class... Ts>
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using void_t = boost::void_t<Ts...>;
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// (since C++11) missing from g++4.8
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template<std::size_t Len, class... Ts>
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struct aligned_union
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{
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static
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std::size_t constexpr alignment_value =
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max_alignof<Ts...>();
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using type = typename std::aligned_storage<
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(Len > max_sizeof<Ts...>()) ? Len : (max_sizeof<Ts...>()),
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alignment_value>::type;
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};
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template<std::size_t Len, class... Ts>
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using aligned_union_t =
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typename aligned_union<Len, Ts...>::type;
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//------------------------------------------------------------------------------
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// for span
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template<class T, class E, class = void>
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struct is_contiguous_container: std::false_type {};
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template<class T, class E>
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struct is_contiguous_container<T, E, void_t<
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decltype(
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std::declval<std::size_t&>() = std::declval<T const&>().size(),
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std::declval<E*&>() = std::declval<T&>().data()),
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typename std::enable_if<
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std::is_same<
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typename std::remove_cv<E>::type,
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typename std::remove_cv<
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typename std::remove_pointer<
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decltype(std::declval<T&>().data())
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>::type
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>::type
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>::value
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>::type>>: std::true_type
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{};
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template <class T, class U>
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T launder_cast(U* u)
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{
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#if defined(__cpp_lib_launder) && __cpp_lib_launder >= 201606
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return std::launder(reinterpret_cast<T>(u));
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#elif defined(BOOST_GCC) && BOOST_GCC_VERSION > 80000
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return __builtin_launder(reinterpret_cast<T>(u));
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#else
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return reinterpret_cast<T>(u);
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#endif
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}
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} // detail
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} // beast
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} // boost
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#endif
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