encoder.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_ENCODING_ENCODER_HPP
#define NDN_CXX_ENCODING_ENCODER_HPP

#include "ndn-cxx/encoding/block.hpp"

namespace ndn {
namespace encoding {

class Encoder : noncopyable
{
public: // common interface between Encoder and Estimator
  size_t
  prependBytes(span<const uint8_t> bytes);

  size_t
  appendBytes(span<const uint8_t> bytes);

  template<class Iterator>
  size_t
  prependRange(Iterator first, Iterator last);

  template<class Iterator>
  size_t
  appendRange(Iterator first, Iterator last);

  size_t
  prependVarNumber(uint64_t number);

  size_t
  appendVarNumber(uint64_t number);

  size_t
  prependNonNegativeInteger(uint64_t integer);

  size_t
  appendNonNegativeInteger(uint64_t integer);

public: // unique interface to the Encoder
  using value_type = Buffer::value_type;
  using iterator = Buffer::iterator;
  using const_iterator = Buffer::const_iterator;

  explicit
  Encoder(size_t totalReserve = MAX_NDN_PACKET_SIZE, size_t reserveFromBack = 400);

  explicit
  Encoder(const Block& block);

  void
  reserve(size_t size, bool addInFront);

  void
  reserveBack(size_t size);

  void
  reserveFront(size_t size);

  size_t
  capacity() const noexcept
  {
    return m_buffer->size();
  }

  shared_ptr<Buffer>
  getBuffer() const noexcept
  {
    return m_buffer;
  }

public: // accessors
  iterator
  begin() noexcept
  {
    return m_begin;
  }

  const_iterator
  begin() const noexcept
  {
    return m_begin;
  }

  iterator
  end() noexcept
  {
    return m_end;
  }

  const_iterator
  end() const noexcept
  {
    return m_end;
  }

  uint8_t*
  data() noexcept
  {
    return &*m_begin;
  }

  const uint8_t*
  data() const noexcept
  {
    return &*m_begin;
  }

  size_t
  size() const noexcept
  {
    return static_cast<size_t>(std::distance(m_begin, m_end));
  }

  Block
  block(bool verifyLength = true) const;

private:
  shared_ptr<Buffer> m_buffer;

  // invariant: m_begin always points to the position of last-written byte (if prepending data)
  iterator m_begin;
  // invariant: m_end always points to the position of next unwritten byte (if appending data)
  iterator m_end;
};

template<class Iterator>
size_t
Encoder::prependRange(Iterator first, Iterator last)
{
  using ValueType = typename std::iterator_traits<Iterator>::value_type;
  static_assert(sizeof(ValueType) == 1 && !std::is_same<ValueType, bool>::value, "");

  size_t length = std::distance(first, last);
  reserveFront(length);

  std::advance(m_begin, -length);
  std::copy(first, last, m_begin);
  return length;
}

template<class Iterator>
size_t
Encoder::appendRange(Iterator first, Iterator last)
{
  using ValueType = typename std::iterator_traits<Iterator>::value_type;
  static_assert(sizeof(ValueType) == 1 && !std::is_same<ValueType, bool>::value, "");

  size_t length = std::distance(first, last);
  reserveBack(length);

  std::copy(first, last, m_end);
  std::advance(m_end, length);
  return length;
}

} // namespace encoding
} // namespace ndn

#endif // NDN_CXX_ENCODING_ENCODER_HPP