kiszk commented on a change in pull request #7507:
URL: https://github.com/apache/arrow/pull/7507#discussion_r465270135
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File path: cpp/src/arrow/array/util.cc
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@@ -74,6 +74,186 @@ class ArrayDataWrapper {
std::shared_ptr<Array>* out_;
};
+class ArrayDataEndianSwapper {
+ public:
+ ArrayDataEndianSwapper(std::shared_ptr<ArrayData>& data, int64_t length)
+ : data_(data), length_(length) {}
+
+ Status SwapType(const DataType& type) { return VisitTypeInline(type, this); }
+
+ Status SwapChildren(std::vector<std::shared_ptr<Field>> child_fields) {
+ int i = 0;
+ for (const auto& child_field : child_fields) {
+ auto orig_data = data_;
+ auto orig_length = length_;
+ data_ = data_->child_data[i++];
+ length_ = data_->length;
+ RETURN_NOT_OK(SwapType(*child_field.get()->type()));
+ length_ = orig_length;
+ data_ = orig_data;
+ }
+ return Status::OK();
+ }
+
+ template <typename T>
+ Status SwapOffset(const T&, int index) {
+ if (data_->buffers[index] == nullptr) {
+ return Status::OK();
+ }
+ using value_type = typename T::c_type;
+ auto buffer = const_cast<value_type*>(
+ reinterpret_cast<const value_type*>(data_->buffers[index]->data()));
+ // offset has one more element rather than data->length
+ int64_t length = length_ + 1;
+ for (int64_t i = 0; i < length; i++) {
+#if ARROW_LITTLE_ENDIAN
+ buffer[i] = BitUtil::FromBigEndian(buffer[i]);
+#else
+ buffer[i] = BitUtil::FromLittleEndian(buffer[i]);
+#endif
+ }
+ return Status::OK();
+ }
+
+ Status SwapSmallOffset(int index = 1) {
+ Int32Type i32;
+ RETURN_NOT_OK(SwapOffset(i32, index));
+ return Status::OK();
+ }
+
+ Status SwapLargeOffset() {
+ Int64Type i64;
+ RETURN_NOT_OK(SwapOffset(i64, 1));
+ return Status::OK();
+ }
Review comment:
Thanks for the good suggestion. Done.
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