Method Unify

cpp/src/arrow/array/array_dict.cc:354–378

      : pool_(pool), value_type_(std::move(value_type)), memo_table_(pool) {}

  Status Unify(const Array& dictionary, std::shared_ptr<Buffer>* out) override {
    if (dictionary.null_count() > 0) {
      return Status::Invalid("Cannot yet unify dictionaries with nulls");
    }
    if (!dictionary.type()->Equals(*value_type_)) {
      return Status::Invalid("Dictionary type different from unifier: ",
                             dictionary.type()->ToString());
    }
    const ArrayType& values = checked_cast<const ArrayType&>(dictionary);
    if (out != nullptr) {
      ARROW_ASSIGN_OR_RAISE(auto result,
                            AllocateBuffer(dictionary.length() * sizeof(int32_t), pool_));
      auto result_raw = reinterpret_cast<int32_t*>(result->mutable_data());
      for (int64_t i = 0; i < values.length(); ++i) {
        RETURN_NOT_OK(memo_table_.GetOrInsert(values.GetView(i), &result_raw[i]));
      }
      *out = std::move(result);
    } else {
      for (int64_t i = 0; i < values.length(); ++i) {
        int32_t unused_memo_index;
        RETURN_NOT_OK(memo_table_.GetOrInsert(values.GetView(i), &unused_memo_index));
      }
    }
    return Status::OK();
  }

  Status Unify(const Array& dictionary) override { return Unify(dictionary, nullptr); }