Method Convert

cpp/src/arrow/json/converter.cc:159–201

      : PrimitiveConverter(pool, type) {}

  Status Convert(const std::shared_ptr<Array>& in, std::shared_ptr<Array>* out) override {
    if (in->type_id() == Type::NA) {
      return MakeArrayOfNull(out_type_, in->length(), pool_).Value(out);
    }
    const auto& dict_array = GetDictionaryArray(in);

    using Builder = typename TypeTraits<T>::BuilderType;
    Builder builder(out_type_, pool_);
    RETURN_NOT_OK(builder.Resize(dict_array.indices()->length()));
    const auto& decimal_type(checked_cast<const DecimalType&>(*out_type_));
    int32_t out_precision = decimal_type.precision();
    int32_t out_scale = decimal_type.scale();

    auto visit_valid = [&](string_view repr) {
      value_type value;
      int32_t precision, scale;
      RETURN_NOT_OK(TypeTraits<T>::BuilderType::ValueType::FromString(
          repr, &value, &precision, &scale));
      if (precision > out_precision) {
        return GenericConversionError(*out_type_, ": ", repr, " requires precision ",
                                      precision);
      }
      if (scale != out_scale) {
        auto result = value.Rescale(scale, out_scale);
        if (ARROW_PREDICT_FALSE(!result.ok())) {
          return GenericConversionError(*out_type_, ": ", repr, " requires scale ",
                                        scale);
        } else {
          value = result.MoveValueUnsafe();
        }
      }
      builder.UnsafeAppend(value);
      return Status::OK();
    };

    auto visit_null = [&builder]() {
      builder.UnsafeAppendNull();
      return Status::OK();
    };

    RETURN_NOT_OK(VisitDictionaryEntries(dict_array, visit_valid, visit_null));
    return builder.Finish(out);
  }
};

template <typename DateTimeType>