Function CheckRoundTrip

cpp/src/arrow/util/rle_encoding_test.cc:693–738

A version of ValidateRle that round-trips the values and returns false if the returned values are not all the same

// A version of ValidateRle that round-trips the values and returns false if
// the returned values are not all the same
bool CheckRoundTrip(const std::vector<int>& values, int bit_width) {
  const int len = 64 * 1024;
#ifdef __EMSCRIPTEN__
  // don't make this on the stack as it is
  // too big for emscripten
  std::vector<uint8_t> buffer_vec(static_cast<size_t>(len));
  uint8_t* buffer = buffer_vec.data();
#else
  uint8_t buffer[len];
#endif
  RleBitPackedEncoder encoder(buffer, len, bit_width);
  for (size_t i = 0; i < values.size(); ++i) {
    bool result = encoder.Put(values[i]);
    if (!result) {
      return false;
    }
  }
  int encoded_len = encoder.Flush();
  int out = 0;

  {
    RleBitPackedDecoder<int> decoder(buffer, encoded_len, bit_width);
    for (size_t i = 0; i < values.size(); ++i) {
      EXPECT_TRUE(decoder.Get(&out));
      if (values[i] != out) {
        return false;
      }
    }
  }

  // Verify batch read
  {
    RleBitPackedDecoder<int> decoder(buffer, encoded_len, bit_width);
    std::vector<int> values_read(values.size());
    if (static_cast<int>(values.size()) !=
        decoder.GetBatch(values_read.data(), static_cast<int>(values.size()))) {
      return false;
    }

    if (values != values_read) {
      return false;
    }
  }

  return true;
}

TEST(RleBitPacked, SpecificSequences) {
  const int len = 1024;