Method SetupEncoderDecoder

cpp/src/parquet/encoding_test.cc:1319–1348

class DictEncoding : public TestArrowBuilderDecoding {
 public:
  void SetupEncoderDecoder() override {
    auto node = schema::ByteArray("name");
    descr_ = std::make_unique<ColumnDescriptor>(node, 0, 0);
    encoder_ = MakeTypedEncoder<ByteArrayType>(Encoding::PLAIN, /*use_dictionary=*/true,
                                               descr_.get());
    if (null_count_ == 0) {
      ASSERT_NO_THROW(encoder_->Put(input_data_.data(), num_values_));
    } else {
      ASSERT_NO_THROW(
          encoder_->PutSpaced(input_data_.data(), num_values_, valid_bits_, 0));
    }
    buffer_ = encoder_->FlushValues();

    auto dict_encoder = dynamic_cast<DictEncoder<ByteArrayType>*>(encoder_.get());
    ASSERT_NE(dict_encoder, nullptr);
    dict_buffer_ =
        AllocateBuffer(default_memory_pool(), dict_encoder->dict_encoded_size());
    dict_encoder->WriteDict(dict_buffer_->mutable_data());

    // Simulate reading the dictionary page followed by a data page
    plain_decoder_ = MakeTypedDecoder<ByteArrayType>(Encoding::PLAIN, descr_.get());
    plain_decoder_->SetData(dict_encoder->num_entries(), dict_buffer_->data(),
                            static_cast<int>(dict_buffer_->size()));

    dict_decoder_ = MakeDictDecoder<ByteArrayType>(descr_.get());
    dict_decoder_->SetDict(plain_decoder_.get());
    dict_decoder_->SetData(num_values_, buffer_->data(),
                           static_cast<int>(buffer_->size()));
    decoder_ = dynamic_cast<ByteArrayDecoder*>(dict_decoder_.get());
  }

 protected:
  std::unique_ptr<ColumnDescriptor> descr_;