bkietz commented on a change in pull request #8309:
URL: https://github.com/apache/arrow/pull/8309#discussion_r497762312
##########
File path: cpp/src/arrow/ipc/json_simple.cc
##########
@@ -50,13 +51,35 @@ namespace json {
using ::arrow::internal::checked_cast;
using ::arrow::internal::checked_pointer_cast;
-static constexpr auto kParseFlags = rj::kParseFullPrecisionFlag |
rj::kParseNanAndInfFlag;
+namespace {
-static Status JSONTypeError(const char* expected_type, rj::Type json_type) {
+constexpr auto kParseFlags = rj::kParseFullPrecisionFlag |
rj::kParseNanAndInfFlag;
+
+Status JSONTypeError(const char* expected_type, rj::Type json_type) {
return Status::Invalid("Expected ", expected_type, " or null, got JSON type
",
json_type);
}
+template <typename Type>
+struct RegularBuilderTraits {
+ using BuilderType = typename TypeTraits<Type>::BuilderType;
+
+ static const std::shared_ptr<DataType>& value_type(
+ const std::shared_ptr<DataType>& type) {
+ return type;
+ }
+};
+
+template <typename Type>
+struct DictionaryBuilderTraits {
+ using BuilderType = DictionaryBuilder<Type>;
+
+ static const std::shared_ptr<DataType>& value_type(
+ const std::shared_ptr<DataType>& type) {
+ return checked_cast<const DictionaryType&>(*type).value_type();
+ }
+};
+
Review comment:
I think the converters would be simplified by passing the `BuilderType`
as the template parameter directly, rather than passing a trait with which to
look it up. `value_type` need not be a trait member at all, I think:
```c++
inline const std::shared_ptr<DataType>& value_type(const
std::shared_ptr<DataType>& type) {
if (type->id() != Type::DICTIONARY) return type;
return checked_cast<const DictionaryType&>(*type).value_type();
}
```
##########
File path: cpp/src/arrow/ipc/json_simple.cc
##########
@@ -412,12 +463,22 @@ class StringConverter final : public
ConcreteConverter<StringConverter<TYPE>> {
// ------------------------------------------------------------------------
// Converter for fixed-size binary arrays
+template <template <typename T> class BuilderTraits = RegularBuilderTraits>
class FixedSizeBinaryConverter final
- : public ConcreteConverter<FixedSizeBinaryConverter> {
+ : public ConcreteConverter<FixedSizeBinaryConverter<BuilderTraits>> {
+ using BuilderType = typename BuilderTraits<FixedSizeBinaryType>::BuilderType;
+
public:
explicit FixedSizeBinaryConverter(const std::shared_ptr<DataType>& type) {
this->type_ = type;
- builder_ = std::make_shared<FixedSizeBinaryBuilder>(type,
default_memory_pool());
+ }
+
+ Status Init() override {
+ std::unique_ptr<ArrayBuilder> builder;
+ RETURN_NOT_OK(MakeBuilder(default_memory_pool(), this->type_, &builder));
+ builder_ = checked_pointer_cast<BuilderType>(std::move(builder));
+ DCHECK(builder_);
+ return Status::OK();
Review comment:
This is repeated several times, could it be simplified by adding a
helper to ConcreteConverter:
```suggestion
return this->MakeBuilder(&builder_);
```
##########
File path: cpp/src/arrow/array/builder_dict.h
##########
@@ -190,6 +190,12 @@ class DictionaryBuilderBase : public ArrayBuilder {
/// \brief The current number of entries in the dictionary
int64_t dictionary_length() const { return memo_table_->size(); }
+ /// \brief The value byte width (for FixedSizeBinaryType)
+ template <typename T1 = T>
+ enable_if_fixed_size_binary<T1, int32_t> byte_width() const {
+ return byte_width_;
+ }
+
Review comment:
This is probably fine. Nit: I'd prefer to get the `FixedSizeBinaryType`
inside the converter and use it's `byte_width()` over propagating the property
to builders
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