icexelloss commented on code in PR #34311:
URL: https://github.com/apache/arrow/pull/34311#discussion_r1127039705
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cpp/src/arrow/compute/row/grouper.cc:
##########
@@ -39,12 +43,330 @@
namespace arrow {
using internal::checked_cast;
+using internal::PrimitiveScalarBase;
namespace compute {
namespace {
-struct GrouperImpl : Grouper {
+constexpr uint32_t kNoGroupId = std::numeric_limits<uint32_t>::max();
+
+using group_id_t = std::remove_const<decltype(kNoGroupId)>::type;
+using GroupIdType = CTypeTraits<group_id_t>::ArrowType;
+auto g_group_id_type = std::make_shared<GroupIdType>();
+
+inline const uint8_t* GetValuesAsBytes(const ArraySpan& data, int64_t offset =
0) {
+ DCHECK_GT(data.type->byte_width(), 0);
+ int64_t absolute_byte_offset = (data.offset + offset) *
data.type->byte_width();
+ return data.GetValues<uint8_t>(1, absolute_byte_offset);
+}
+
+template <typename Value>
+Status CheckForGetNextSegment(const std::vector<Value>& values, int64_t length,
+ int64_t offset, const std::vector<TypeHolder>&
key_types) {
+ if (offset < 0 || offset > length) {
+ return Status::Invalid("invalid grouping segmenter offset: ", offset);
+ }
+ if (values.size() != key_types.size()) {
+ return Status::Invalid("expected batch size ", key_types.size(), " but got
",
+ values.size());
+ }
+ for (size_t i = 0; i < key_types.size(); i++) {
+ const auto& value = values[i];
+ const auto& key_type = key_types[i];
+ if (*value.type() != *key_type.type) {
+ return Status::Invalid("expected batch value ", i, " of type ",
*key_type.type,
+ " but got ", *value.type());
+ }
+ }
+ return Status::OK();
+}
+
+template <typename Batch>
+enable_if_t<std::is_same<Batch, ExecSpan>::value || std::is_same<Batch,
ExecBatch>::value,
+ Status>
+CheckForGetNextSegment(const Batch& batch, int64_t offset,
+ const std::vector<TypeHolder>& key_types) {
+ return CheckForGetNextSegment(batch.values, batch.length, offset, key_types);
+}
+
+struct BaseRowSegmenter : public RowSegmenter {
+ explicit BaseRowSegmenter(const std::vector<TypeHolder>& key_types)
+ : key_types_(key_types) {}
+
+ const std::vector<TypeHolder>& key_types() const override { return
key_types_; }
+
+ std::vector<TypeHolder> key_types_;
+};
+
+Segment MakeSegment(int64_t batch_length, int64_t offset, int64_t length, bool
extends) {
+ return Segment{offset, length, offset + length >= batch_length, extends};
+}
+
+int64_t GetMatchLength(const uint8_t* match_bytes, int64_t match_width,
+ const uint8_t* array_bytes, int64_t offset, int64_t
length) {
+ int64_t cursor, byte_cursor;
+ for (cursor = offset, byte_cursor = match_width * cursor; cursor < length;
+ cursor++, byte_cursor += match_width) {
+ if (memcmp(match_bytes, array_bytes + byte_cursor,
+ static_cast<size_t>(match_width)) != 0) {
+ break;
+ }
+ }
+ return std::min(cursor, length) - offset;
+}
+
+using ExtendFunc = std::function<bool(const void*)>;
+constexpr bool kDefaultExtends = true;
+constexpr bool kEmptyExtends = true;
+
+struct NoKeysSegmenter : public BaseRowSegmenter {
+ static std::unique_ptr<RowSegmenter> Make() {
+ return std::make_unique<NoKeysSegmenter>();
+ }
+
+ NoKeysSegmenter() : BaseRowSegmenter({}) {}
+
+ Status Reset() override { return Status::OK(); }
+
+ Result<Segment> GetNextSegment(const ExecSpan& batch, int64_t offset)
override {
+ ARROW_RETURN_NOT_OK(CheckForGetNextSegment(batch, offset, {}));
+ return MakeSegment(batch.length, offset, batch.length - offset,
kDefaultExtends);
+ }
+};
+
+struct SimpleKeySegmenter : public BaseRowSegmenter {
+ static Result<std::unique_ptr<RowSegmenter>> Make(TypeHolder key_type) {
+ return std::make_unique<SimpleKeySegmenter>(key_type);
+ }
+
+ explicit SimpleKeySegmenter(TypeHolder key_type)
+ : BaseRowSegmenter({key_type}), key_type_(key_types_[0]),
save_key_data_() {}
+
+ Status CheckType(const DataType& type) {
+ if (!is_fixed_width(type)) {
+ return Status::Invalid("SimpleKeySegmenter does not support type ",
type);
+ }
+ return Status::OK();
+ }
+
+ Status Reset() override {
+ save_key_data_.resize(0);
+ return Status::OK();
+ }
+
+ // Checks whether the given grouping data extends the current segment, i.e.,
is equal to
+ // previously seen grouping data, which is updated with each invocation.
+ bool Extend(const void* data) {
+ size_t byte_width = static_cast<size_t>(key_type_.type->byte_width());
+ bool extends = save_key_data_.size() != byte_width
+ ? kDefaultExtends
+ : 0 == memcmp(save_key_data_.data(), data, byte_width);
+ save_key_data_.resize(byte_width);
+ memcpy(save_key_data_.data(), data, byte_width);
+ return extends;
+ }
+
+ Result<Segment> GetNextSegment(const Scalar& scalar, int64_t offset, int64_t
length) {
+ ARROW_RETURN_NOT_OK(CheckType(*scalar.type));
+ if (!scalar.is_valid) {
+ return Status::Invalid("segmenting an invalid scalar");
+ }
+ auto data = checked_cast<const PrimitiveScalarBase&>(scalar).data();
+ bool extends = length > 0 ? Extend(data) : kEmptyExtends;
+ return MakeSegment(length, offset, length, extends);
+ }
+
+ Result<Segment> GetNextSegment(const DataType& array_type, const uint8_t*
array_bytes,
Review Comment:
Can we add DCHECK here that offset / length doesn't go out of bound? We are
doing pointer math here so we should be "very" careful.
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