/usr/include/boost/beast/core/detail
Edit: /usr/include/boost/beast/core/detail/variant.hpp (4889B)
//
// 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_VARIANT_HPP
#define BOOST_BEAST_DETAIL_VARIANT_HPP
#include
#include
#include
namespace boost {
namespace beast {
namespace detail {
// This simple variant gets the job done without
// causing too much trouble with template depth:
//
// * Always allows an empty state I==0
// * emplace() and get() support 1-based indexes only
// * Basic exception guarantee
// * Max 255 types
//
template
class variant
{
detail::aligned_union_t<1, TN...> buf_;
unsigned char i_ = 0;
struct destroy
{
variant& self;
void operator()(mp11::mp_size_t<0>)
{
}
template
void operator()(I) noexcept
{
using T =
mp11::mp_at_c;
detail::launder_cast(&self.buf_)->~T();
}
};
struct copy
{
variant& self;
variant const& other;
void operator()(mp11::mp_size_t<0>)
{
}
template
void operator()(I)
{
using T =
mp11::mp_at_c;
::new(&self.buf_) T(
*detail::launder_cast(&other.buf_));
self.i_ = I::value;
}
};
struct move
{
variant& self;
variant& other;
void operator()(mp11::mp_size_t<0>)
{
}
template
void operator()(I)
{
using T =
mp11::mp_at_c;
::new(&self.buf_) T(std::move(
*detail::launder_cast(&other.buf_)));
detail::launder_cast(&other.buf_)->~T();
self.i_ = I::value;
}
};
struct equals
{
variant const& self;
variant const& other;
bool operator()(mp11::mp_size_t<0>)
{
return true;
}
template
bool operator()(I)
{
using T =
mp11::mp_at_c;
return
*detail::launder_cast(&self.buf_) ==
*detail::launder_cast(&other.buf_);
}
};
void destruct()
{
mp11::mp_with_index<
sizeof...(TN) + 1>(
i_, destroy{*this});
i_ = 0;
}
void copy_construct(variant const& other)
{
mp11::mp_with_index<
sizeof...(TN) + 1>(
other.i_, copy{*this, other});
}
void move_construct(variant& other)
{
mp11::mp_with_index<
sizeof...(TN) + 1>(
other.i_, move{*this, other});
other.i_ = 0;
}
public:
variant() = default;
~variant()
{
destruct();
}
bool
operator==(variant const& other) const
{
if(i_ != other.i_)
return false;
return mp11::mp_with_index<
sizeof...(TN) + 1>(
i_, equals{*this, other});
}
// 0 = empty
unsigned char
index() const
{
return i_;
}
// moved-from object becomes empty
variant(variant&& other) noexcept
{
move_construct(other);
}
variant(variant const& other)
{
copy_construct(other);
}
// moved-from object becomes empty
variant& operator=(variant&& other)
{
if(this != &other)
{
destruct();
move_construct(other);
}
return *this;
}
variant& operator=(variant const& other)
{
if(this != &other)
{
destruct();
copy_construct(other);
}
return *this;
}
template
void
emplace(Args&&... args) noexcept
{
destruct();
::new(&buf_) mp11::mp_at_c(
std::forward(args)...);
i_ = I;
}
template
mp11::mp_at_c&
get()
{
BOOST_ASSERT(i_ == I);
return *detail::launder_cast<
mp11::mp_at_c*>(&buf_);
}
template
mp11::mp_at_c const&
get() const
{
BOOST_ASSERT(i_ == I);
return *detail::launder_cast<
mp11::mp_at_c const*>(&buf_);
}
void
reset()
{
destruct();
}
};
} // detail
} // beast
} // boost
#endif