Event.hpp

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// The Reactive C++ Toolbox.
// Copyright (C) 2013-2019 Swirly Cloud Limited
// Copyright (C) 2022 Reactive Markets Limited
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
 
#ifndef TOOLBOX_IO_EVENT_HPP
#define TOOLBOX_IO_EVENT_HPP
 
#include <cstdint>
#include <utility>
 
namespace toolbox {
inline namespace io {
 
struct MsgEvent {
    int type;
    char data[1524];
};
static_assert(std::is_standard_layout_v<MsgEvent>
              && std::is_trivially_default_constructible_v<MsgEvent>
              && std::is_trivially_copyable_v<MsgEvent>);
static_assert(sizeof(MsgEvent) + sizeof(std::int64_t) == 1536);
 
template <typename DataT>
void emplace_event(MsgEvent& ev, int type) noexcept
{
    static_assert(alignof(DataT) <= 8);
    static_assert(std::is_nothrow_default_constructible_v<DataT>);
    static_assert(std::is_trivially_copyable_v<DataT>);
    ev.type = type;
    ::new (ev.data) DataT{};
}
 
template <typename DataT, typename... ArgsT>
void emplace_event(MsgEvent& ev, int type, ArgsT&&... args) noexcept
{
    static_assert(alignof(DataT) <= 8);
    static_assert(std::is_nothrow_constructible_v<DataT, ArgsT...>);
    static_assert(std::is_trivially_copyable_v<DataT>);
    ev.type = type;
    ::new (ev.data) DataT{std::forward<ArgsT>(args)...};
}
 
template <typename DataT>
const DataT& data(const MsgEvent& ev) noexcept
{
    return *reinterpret_cast<const DataT*>(ev.data);
}
 
template <typename DataT>
DataT& data(MsgEvent& ev) noexcept
{
    return *reinterpret_cast<DataT*>(ev.data);
}
 
} // namespace io
} // namespace toolbox
 
#endif // TOOLBOX_IO_EVENT_HPP