pitrou commented on code in PR #13364:
URL: https://github.com/apache/arrow/pull/13364#discussion_r896663585
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cpp/src/arrow/array/data.h:
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@@ -242,6 +245,131 @@ struct ARROW_EXPORT ArrayData {
std::shared_ptr<ArrayData> dictionary;
};
+/// \brief A non-owning Buffer reference
+struct ARROW_EXPORT BufferSpan {
+ // It is the user of this class's responsibility to ensure that
+ // buffers that were const originally are not written to
+ // accidentally.
+ uint8_t* data = NULLPTR;
+ int64_t size = 0;
+ // Pointer back to buffer that owns this memory
+ const std::shared_ptr<Buffer>* owner = NULLPTR;
+};
+
+/// \brief EXPERIMENTAL: A non-owning ArrayData reference that is cheaply
+/// copyable and does not contain any shared_ptr objects. Do not use in public
+/// APIs aside from compute kernels for now
+struct ARROW_EXPORT ArraySpan {
+ const DataType* type = NULLPTR;
+ int64_t length = 0;
+ mutable int64_t null_count = kUnknownNullCount;
+ int64_t offset = 0;
+ BufferSpan buffers[3];
+
+ ArraySpan() = default;
+
+ explicit ArraySpan(const DataType* type, int64_t length) : type(type),
length(length) {}
+
+ ArraySpan(const ArrayData& data) { // NOLINT implicit conversion
+ SetMembers(data);
+ }
+ ArraySpan(const Scalar& data) { // NOLINT implicit converstion
+ FillFromScalar(data);
+ }
+
+ /// If dictionary-encoded, put dictionary in the first entry
+ std::vector<ArraySpan> child_data;
+
+ /// \brief Populate ArraySpan to look like an array of length 1 pointing at
+ /// the data members of a Scalar value
+ void FillFromScalar(const Scalar& value);
+
+ void SetMembers(const ArrayData& data);
+
+ void SetBuffer(int index, const std::shared_ptr<Buffer>& buffer) {
+ this->buffers[index].data = const_cast<uint8_t*>(buffer->data());
+ this->buffers[index].size = buffer->size();
+ this->buffers[index].owner = &buffer;
+ }
+
+ void ClearBuffer(int index) {
+ this->buffers[index].data = NULLPTR;
+ this->buffers[index].size = 0;
+ this->buffers[index].owner = NULLPTR;
+ }
+
+ const ArraySpan& dictionary() const { return child_data[0]; }
+
+ /// \brief Return the number of buffers (out of 3) that are used to
+ /// constitute this array
+ int num_buffers() const;
+
+ // Access a buffer's data as a typed C pointer
+ template <typename T>
+ inline T* GetValues(int i, int64_t absolute_offset) {
+ return reinterpret_cast<T*>(buffers[i].data) + absolute_offset;
+ }
+
+ template <typename T>
+ inline T* GetValues(int i) {
+ return GetValues<T>(i, this->offset);
+ }
+
+ // Access a buffer's data as a typed C pointer
+ template <typename T>
+ inline const T* GetValues(int i, int64_t absolute_offset) const {
+ return reinterpret_cast<const T*>(buffers[i].data) + absolute_offset;
+ }
+
+ template <typename T>
+ inline const T* GetValues(int i) const {
+ return GetValues<T>(i, this->offset);
+ }
+
+ bool IsNull(int64_t i) const {
+ return ((this->buffers[0].data != NULLPTR)
+ ? !bit_util::GetBit(this->buffers[0].data, i + this->offset)
+ : this->null_count == this->length);
+ }
+
+ bool IsValid(int64_t i) const {
+ return ((this->buffers[0].data != NULLPTR)
+ ? bit_util::GetBit(this->buffers[0].data, i + this->offset)
+ : this->null_count != this->length);
+ }
Review Comment:
This is incorrect for union arrays whether the first buffer contains the
union type codes.
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