transform-base.hpp

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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2013-2022 Regents of the University of California.
 *
 * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
 *
 * ndn-cxx library is free software: you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later version.
 *
 * ndn-cxx library is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
 * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
 *
 * You should have received copies of the GNU General Public License and GNU Lesser
 * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
 * <http://www.gnu.org/licenses/>.
 *
 * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
 */

#ifndef NDN_CXX_SECURITY_TRANSFORM_BASE_HPP
#define NDN_CXX_SECURITY_TRANSFORM_BASE_HPP

#include "ndn-cxx/detail/common.hpp"
#include "ndn-cxx/util/span.hpp"

#include <vector>

namespace ndn {
namespace security {
namespace transform {

class Error : public std::runtime_error
{
public:
  Error(size_t index, const std::string& what);

  size_t
  getIndex() const
  {
    return m_index;
  }

private:
  size_t m_index;
};

class Downstream : noncopyable
{
public:
  virtual
  ~Downstream() = default;

  size_t
  write(span<const uint8_t> buf);

  void
  end();

  bool
  isEnd() const
  {
    return m_isEnd;
  }

  void
  setIndex(size_t index)
  {
    m_index = index;
  }

  size_t
  getIndex() const
  {
    return m_index;
  }

protected:
  Downstream() = default;

private:
  virtual size_t
  doWrite(span<const uint8_t> buf) = 0;

  virtual void
  doEnd() = 0;

private:
  size_t m_index = 0;
  bool m_isEnd = false;
};

class Upstream
{
public:
  virtual
  ~Upstream() = default;

protected:
  Upstream() = default;

  void
  appendChain(unique_ptr<Downstream> tail);

  Downstream*
  getNext()
  {
    return m_next.get();
  }

protected:
  unique_ptr<Downstream> m_next;
};

class Transform : public Upstream,
                  public Downstream
{
protected:
  using OBuffer = std::vector<uint8_t>;

  Transform() = default;

  void
  flushOutputBuffer();

  void
  flushAllOutput();

  void
  setOutputBuffer(unique_ptr<OBuffer> buffer);

  bool
  isOutputBufferEmpty() const;

private:
  size_t
  doWrite(span<const uint8_t> data) final;

  void
  doEnd() final;

  virtual void
  preTransform();

  virtual size_t
  convert(span<const uint8_t> data) = 0;

  virtual void
  finalize();

private:
  unique_ptr<OBuffer> m_oBuffer;
  size_t m_outputOffset = 0;
};

class Sink : public Downstream
{
};

class Source : public Upstream
{
public:
  Source&
  operator>>(unique_ptr<Transform> transform);

  void
  operator>>(unique_ptr<Sink> sink);

protected:
  Source() = default;

  void
  pump();

  size_t
  getIndex() const
  {
    return 0;
  }

private:
  virtual void
  doPump() = 0;

private:
  size_t m_nModules = 1; // count of modules in the chain starting from (and including) this Source
};

} // namespace transform
} // namespace security
} // namespace ndn

#endif // NDN_CXX_SECURITY_TRANSFORM_BASE_HPP