Method ExtractString

libs/coding/text_storage.hpp:236–278

  template <typename Reader>
  std::string ExtractString(Reader & reader, size_t stringIx)
  {
    InitializeIfNeeded(reader);

    auto const blockIx = m_index.GetBlockIx(stringIx);
    CHECK_LESS(blockIx, m_index.GetNumBlockInfos(), ());

    auto const & bi = m_index.GetBlockInfo(blockIx);

    bool found;
    auto & entry = m_cache.Find(blockIx, found);
    if (!found)
    {
      NonOwningReaderSource source(reader);
      source.Skip(bi.m_offset);

      entry.m_value.clear();
      entry.m_subs.resize(static_cast<size_t>(bi.m_subs));

      uint64_t offset = 0;
      for (size_t i = 0; i < entry.m_subs.size(); ++i)
      {
        auto & sub = entry.m_subs[i];
        sub.m_offset = offset;
        sub.m_length = ReadVarUint<uint64_t>(source);
        CHECK_GREATER_OR_EQUAL(sub.m_offset + sub.m_length, sub.m_offset, ());
        offset += sub.m_length;
      }
      entry.m_value = BWTCoder::ReadAndDecodeBlock(source);
    }

    ASSERT_GREATER_OR_EQUAL(stringIx, bi.From(), ());
    ASSERT_LESS(stringIx, bi.To(), ());

    stringIx -= bi.From();
    ASSERT_LESS(stringIx, entry.m_subs.size(), ());

    auto const & si = entry.m_subs[stringIx];
    auto const & value = entry.m_value;
    ASSERT_LESS_OR_EQUAL(si.m_offset + si.m_length, value.size(), ());
    auto const beg = value.begin() + si.m_offset;
    return std::string(beg, beg + si.m_length);
  }

private:
  struct StringInfo