Status VersionEdit::DecodeFrom()

in db/version_edit.cc [109:210]
89 lines of code
28 McCabe index (conditional complexity)

Status VersionEdit::DecodeFrom(const Slice& src) {
  Clear();
  Slice input = src;
  const char* msg = NULL;
  uint32_t tag;

  // Temporary storage for parsing
  int level;
  uint64_t number;
  FileMetaData f;
  Slice str;
  InternalKey key;

  while (msg == NULL && GetVarint32(&input, &tag)) {
    switch (tag) {
      case kComparator:
        if (GetLengthPrefixedSlice(&input, &str)) {
          comparator_ = str.ToString();
          has_comparator_ = true;
        } else {
          msg = "comparator name";
        }
        break;

      case kLogNumber:
        if (GetVarint64(&input, &log_number_)) {
          has_log_number_ = true;
        } else {
          msg = "log number";
        }
        break;

      case kPrevLogNumber:
        if (GetVarint64(&input, &prev_log_number_)) {
          has_prev_log_number_ = true;
        } else {
          msg = "previous log number";
        }
        break;

      case kNextFileNumber:
        if (GetVarint64(&input, &next_file_number_)) {
          has_next_file_number_ = true;
        } else {
          msg = "next file number";
        }
        break;

      case kLastSequence:
        if (GetVarint64(&input, &last_sequence_)) {
          has_last_sequence_ = true;
        } else {
          msg = "last sequence number";
        }
        break;

      case kCompactPointer:
        if (GetLevel(&input, &level) &&
            GetInternalKey(&input, &key)) {
          compact_pointers_.push_back(std::make_pair(level, key));
        } else {
          msg = "compaction pointer";
        }
        break;

      case kDeletedFile:
        if (GetLevel(&input, &level) &&
            GetVarint64(&input, &number)) {
          deleted_files_.insert(std::make_pair(level, number));
        } else {
          msg = "deleted file";
        }
        break;

      case kNewFile:
        if (GetLevel(&input, &level) &&
            GetVarint64(&input, &f.number) &&
            GetVarint64(&input, &f.file_size) &&
            GetInternalKey(&input, &f.smallest) &&
            GetInternalKey(&input, &f.largest)) {
          new_files_.push_back(std::make_pair(level, f));
        } else {
          msg = "new-file entry";
        }
        break;

      default:
        msg = "unknown tag";
        break;
    }
  }

  if (msg == NULL && !input.empty()) {
    msg = "invalid tag";
  }

  Status result;
  if (msg != NULL) {
    result = Status::Corruption("VersionEdit", msg);
  }
  return result;
}