quic/core/frames/quic_inlined_frame.h

// Copyright (c) 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef QUICHE_QUIC_CORE_FRAMES_QUIC_INLINED_FRAME_H_
#define QUICHE_QUIC_CORE_FRAMES_QUIC_INLINED_FRAME_H_

#include <type_traits>

#include "quic/core/quic_types.h"
#include "quic/platform/api/quic_export.h"

namespace quic {

// QuicInlinedFrame is the base class of all frame types that is inlined in the
// QuicFrame class. It gurantees all inlined frame types contain a 'type' field
// at offset 0, such that QuicFrame.type can get the correct frame type for both
// inline and out-of-line frame types.
template <typename DerivedT>
struct QUIC_EXPORT_PRIVATE QuicInlinedFrame {
  QuicInlinedFrame(QuicFrameType type) {
    static_cast<DerivedT*>(this)->type = type;
    static_assert(std::is_standard_layout<DerivedT>::value,
                  "Inlined frame must have a standard layout");
    static_assert(offsetof(DerivedT, type) == 0,
                  "type must be the first field.");
    static_assert(sizeof(DerivedT) <= 24,
                  "Frames larger than 24 bytes should not be inlined.");
  }
};

}  // namespace quic

#endif  // QUICHE_QUIC_CORE_FRAMES_QUIC_INLINED_FRAME_H_