block-helpers.hpp

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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
#ifndef NDN_ENCODING_BLOCK_HELPERS_HPP
#define NDN_ENCODING_BLOCK_HELPERS_HPP

#include "block.hpp"
#include "encoding-buffer.hpp"
#include "../util/concepts.hpp"

#include <iterator>

namespace ndn {
namespace encoding {

template<Tag TAG>
size_t
prependNonNegativeIntegerBlock(EncodingImpl<TAG>& encoder, uint32_t type, uint64_t value);

Block
makeNonNegativeIntegerBlock(uint32_t type, uint64_t value);

uint64_t
readNonNegativeInteger(const Block& block);


template<Tag TAG>
size_t
prependEmptyBlock(EncodingImpl<TAG>& encoder, uint32_t type);

Block
makeEmptyBlock(uint32_t type);


template<Tag TAG>
size_t
prependStringBlock(EncodingImpl<TAG>& encoder, uint32_t type, const std::string& value);

Block
makeStringBlock(uint32_t type, const std::string& value);

std::string
readString(const Block& block);


Block
makeBinaryBlock(uint32_t type, const uint8_t* value, size_t length);

Block
makeBinaryBlock(uint32_t type, const char* value, size_t length);

template<class Iterator>
class DataBlockFast
{
public:
  BOOST_CONCEPT_ASSERT((boost::RandomAccessIterator<Iterator>));

  static Block
  makeBlock(uint32_t type, Iterator first, Iterator last)
  {
    EncodingEstimator estimator;
    size_t valueLength = last - first;
    size_t totalLength = valueLength;
    totalLength += estimator.prependVarNumber(valueLength);
    totalLength += estimator.prependVarNumber(type);

    EncodingBuffer encoder(totalLength, 0);
    encoder.prependRange(first, last);
    encoder.prependVarNumber(valueLength);
    encoder.prependVarNumber(type);

    return encoder.block();
  }
};

template<class Iterator>
class DataBlockSlow
{
public:
  BOOST_CONCEPT_ASSERT((boost::InputIterator<Iterator>));

  static Block
  makeBlock(uint32_t type, Iterator first, Iterator last)
  {
    // reserve 4 bytes in front (common for 1(type)-3(length) encoding
    // Actual size will be adjusted as necessary by the encoder
    EncodingBuffer encoder(4, 4);
    size_t valueLength = encoder.appendRange(first, last);
    encoder.prependVarNumber(valueLength);
    encoder.prependVarNumber(type);

    return encoder.block();
  }
};

template<class Iterator>
inline Block
makeBinaryBlock(uint32_t type, Iterator first, Iterator last)
{
  static_assert(sizeof(typename std::iterator_traits<Iterator>::value_type) == 1,
                "Iterator should point only to char or unsigned char");

  typedef typename boost::mpl::if_<
    std::is_base_of<std::random_access_iterator_tag,
                    typename std::iterator_traits<Iterator>::iterator_category>,
    DataBlockFast<Iterator>,
    DataBlockSlow<Iterator>>::type DataBlock;

  return DataBlock::makeBlock(type, first, last);
}


template<Tag TAG, class U>
inline size_t
prependNestedBlock(EncodingImpl<TAG>& encoder, uint32_t type, const U& value)
{
  BOOST_CONCEPT_ASSERT((WireEncodableWithEncodingBuffer<U>));

  size_t valueLength = value.wireEncode(encoder);
  size_t totalLength = valueLength;
  totalLength += encoder.prependVarNumber(valueLength);
  totalLength += encoder.prependVarNumber(type);

  return totalLength;
}

template<class U>
inline Block
makeNestedBlock(uint32_t type, const U& value)
{
  EncodingEstimator estimator;
  size_t totalLength = prependNestedBlock(estimator, type, value);

  EncodingBuffer encoder(totalLength, 0);
  prependNestedBlock(encoder, type, value);

  return encoder.block();
}

} // namespace encoding

using encoding::makeNonNegativeIntegerBlock;
using encoding::readNonNegativeInteger;
using encoding::makeEmptyBlock;
using encoding::makeStringBlock;
using encoding::readString;
using encoding::makeBinaryBlock;
using encoding::makeNestedBlock;

} // namespace ndn

#endif // NDN_ENCODING_BLOCK_HELPERS_HPP