io.hpp

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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2013-2019 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_UTIL_IO_HPP
#define NDN_UTIL_IO_HPP

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

#include <fstream>

namespace ndn {
namespace io {

class Error : public std::runtime_error
{
public:
  using std::runtime_error::runtime_error;
};

enum IoEncoding {
  NO_ENCODING,

  BASE64,

  HEX
};

namespace detail {

template<typename T>
static void
checkInnerError(typename T::Error*)
{
  static_assert(std::is_base_of<tlv::Error, typename T::Error>::value,
                "T::Error, if declared, must inherit from ndn::tlv::Error");
}

template<typename T>
static void
checkInnerError(...)
{
  // T::Error is not declared
}

} // namespace detail

optional<Block>
loadBlock(std::istream& is, IoEncoding encoding = BASE64);

template<typename T>
shared_ptr<T>
load(std::istream& is, IoEncoding encoding = BASE64)
{
  BOOST_CONCEPT_ASSERT((WireDecodable<T>));
  detail::checkInnerError<T>(nullptr);

  optional<Block> block = loadBlock(is, encoding);
  if (!block) {
    return nullptr;
  }

  try {
    return make_shared<T>(*block);
  }
  catch (const tlv::Error&) {
    return nullptr;
  }
}

template<typename T>
shared_ptr<T>
load(const std::string& filename, IoEncoding encoding = BASE64)
{
  std::ifstream is(filename);
  return load<T>(is, encoding);
}

void
saveBlock(const Block& block, std::ostream& os, IoEncoding encoding = BASE64);

template<typename T>
void
save(const T& obj, std::ostream& os, IoEncoding encoding = BASE64)
{
  BOOST_CONCEPT_ASSERT((WireEncodable<T>));
  detail::checkInnerError<T>(nullptr);

  Block block;
  try {
    block = obj.wireEncode();
  }
  catch (const tlv::Error&) {
    NDN_THROW_NESTED(Error("Encode error during save"));
  }

  saveBlock(block, os, encoding);
}

template<typename T>
void
save(const T& obj, const std::string& filename, IoEncoding encoding = BASE64)
{
  std::ofstream os(filename);
  save(obj, os, encoding);
}

} // namespace io
} // namespace ndn

#endif // NDN_UTIL_IO_HPP