buffer_writer.h

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// === buffer_writer.h =================================================================================================
//                                               Sen Infrastructure
//                   Released under the Apache License v2.0 (SPDX-License-Identifier Apache-2.0).
//                                    See the LICENSE.txt file for more information.
//                   © Airbus SAS, Airbus Helicopters, and Airbus Defence and Space SAU/GmbH/SAS.
// =====================================================================================================================
 
#ifndef SEN_CORE_IO_BUFFER_WRITER_H
#define SEN_CORE_IO_BUFFER_WRITER_H
 
#include "sen/core/base/span.h"
 
#include <vector>
 
namespace sen
{

class Writer
{
  SEN_NOCOPY_NOMOVE(Writer)
 
public:
  Writer() noexcept = default;
  virtual ~Writer() noexcept = default;
 
public:
  virtual uint8_t* advance(size_t size) = 0;

  virtual void reverse(size_t size) = 0;
};

class BufferWriter final: public Writer
{
  SEN_NOCOPY_NOMOVE(BufferWriter)
 
public:
  explicit BufferWriter(Span<uint8_t> buffer) noexcept: cursor_(buffer.data()) {}
  ~BufferWriter() override = default;
 
public:  // implements sen::Writer
  [[nodiscard]] uint8_t* advance(size_t size) override;
  void reverse(size_t size) override
  {
    cursor_ -= size;  // NOLINT(cppcoreguidelines-pro-bounds-pointer-arithmetic)
  }
 
private:
  uint8_t* cursor_;
};

template <typename Container = std::vector<uint8_t>>
class ResizableBufferWriter final: public Writer
{
  SEN_NOCOPY_NOMOVE(ResizableBufferWriter)
 
public:
  explicit ResizableBufferWriter(Container& buffer) noexcept: buffer_(buffer) {}
  ~ResizableBufferWriter() override = default;
 
public:  // implements sen::Writer
  [[nodiscard]] uint8_t* advance(size_t size) override;
  void reverse(size_t size) override { buffer_.resize(buffer_.size() - size); }
 
private:
  Container& buffer_;
};
 
//----------------------------------------------------------------------------------------------------------------------
// Inline implementation
//----------------------------------------------------------------------------------------------------------------------
 
//--------------------------------------------------------------------------------------------------------------
// BufferWriter
//--------------------------------------------------------------------------------------------------------------
 
inline uint8_t* BufferWriter::advance(size_t size)
{
  auto* oldCursor = cursor_;
  cursor_ += size;  // NOLINT(cppcoreguidelines-pro-bounds-pointer-arithmetic)
  return oldCursor;
}
 
//--------------------------------------------------------------------------------------------------------------
// ResizableBufferWriter
//--------------------------------------------------------------------------------------------------------------
 
template <typename Container>
inline uint8_t* ResizableBufferWriter<Container>::advance(size_t size)
{
  const auto cursor = buffer_.size();
  buffer_.resize(buffer_.size() + size);
  return buffer_.data() + cursor;  // NOLINT(cppcoreguidelines-pro-bounds-pointer-arithmetic)
}
 
}  // namespace sen
 
#endif  // SEN_CORE_IO_BUFFER_WRITER_H