Method SerializeTrafficKeys

libs/traffic/traffic_info.cpp:224–285

static

// static
void TrafficInfo::SerializeTrafficKeys(vector<RoadSegmentId> const & keys, vector<uint8_t> & result)
{
  vector<uint32_t> fids;
  vector<size_t> numSegs;
  vector<bool> oneWay;
  for (size_t i = 0; i < keys.size();)
  {
    size_t j = i;
    while (j < keys.size() && keys[i].m_fid == keys[j].m_fid)
      ++j;

    bool ow = true;
    for (size_t k = i; k < j; ++k)
    {
      if (keys[k].m_dir == RoadSegmentId::kReverseDirection)
      {
        ow = false;
        break;
      }
    }

    auto const numDirs = ow ? 1 : 2;
    size_t numSegsForThisFid = j - i;
    CHECK_GREATER(numDirs, 0, ());
    CHECK_EQUAL(numSegsForThisFid % numDirs, 0, ());
    numSegsForThisFid /= numDirs;

    fids.push_back(keys[i].m_fid);
    numSegs.push_back(numSegsForThisFid);
    oneWay.push_back(ow);

    i = j;
  }

  MemWriter<vector<uint8_t>> memWriter(result);
  WriteToSink(memWriter, kLatestKeysVersion);
  WriteVarUint(memWriter, fids.size());

  {
    BitWriter<decltype(memWriter)> bitWriter(memWriter);

    uint32_t prevFid = 0;
    for (auto const & fid : fids)
    {
      uint64_t const fidDiff = static_cast<uint64_t>(fid - prevFid);
      bool ok = coding::GammaCoder::Encode(bitWriter, fidDiff + 1);
      ASSERT(ok, ());
      UNUSED_VALUE(ok);
      prevFid = fid;
    }

    for (auto const & s : numSegs)
    {
      bool ok = coding::GammaCoder::Encode(bitWriter, s + 1);
      ASSERT(ok, ());
      UNUSED_VALUE(ok);
    }