scovich commented on code in PR #7666:
URL: https://github.com/apache/arrow-rs/pull/7666#discussion_r2151054705
##########
parquet-variant/src/variant.rs:
##########
@@ -300,62 +303,218 @@ impl<'m> VariantMetadata<'m> {
}
}
-#[derive(Clone, Copy, Debug, PartialEq)]
-pub struct VariantObject<'m, 'v> {
- pub metadata: &'m VariantMetadata<'m>,
- pub value: &'v [u8],
+#[derive(Clone, Debug, PartialEq)]
+pub struct VariantObjectHeader {
+ field_offset_size: OffsetSizeBytes,
+ field_id_size: OffsetSizeBytes,
+ num_elements: usize,
+ field_ids_start_byte: usize,
+ field_offsets_start_byte: usize,
+ values_start_byte: usize,
}
-impl<'m, 'v> VariantObject<'m, 'v> {
- pub fn fields(&self) -> Result<impl Iterator<Item = (&'m str, Variant<'m,
'v>)>, ArrowError> {
- todo!();
- #[allow(unreachable_code)] // Just to infer the return type
- Ok(vec![].into_iter())
+
+impl VariantObjectHeader {
+ pub fn try_new(value: &[u8]) -> Result<Self, ArrowError> {
+ // Parse the header byte to get object parameters
+ let header = first_byte_from_slice(value)?;
+ let value_header = header >> 2;
+
+ let field_offset_size_minus_one = value_header & 0x03; // Last 2 bits
+ let field_id_size_minus_one = (value_header >> 2) & 0x03; // Next 2
bits
+ let is_large = value_header & 0x10; // 5th bit
+
+ let field_offset_size =
OffsetSizeBytes::try_new(field_offset_size_minus_one)?;
+ let field_id_size = OffsetSizeBytes::try_new(field_id_size_minus_one)?;
+
+ // Determine num_elements size based on is_large flag
+ let num_elements_size = if is_large != 0 {
+ OffsetSizeBytes::Four
+ } else {
+ OffsetSizeBytes::One
+ };
+
+ // Parse num_elements
+ let num_elements = num_elements_size.unpack_usize(value, 1, 0)?;
+
+ // Calculate byte offsets for different sections
+ let field_ids_start_byte = 1 + num_elements_size as usize;
+ let field_offsets_start_byte = field_ids_start_byte + num_elements *
field_id_size as usize;
+ let values_start_byte =
+ field_offsets_start_byte + (num_elements + 1) * field_offset_size
as usize;
+
+ // Verify that the last field offset array entry is inside the value
slice
+ let last_field_offset_byte =
+ field_offsets_start_byte + (num_elements + 1) * field_offset_size
as usize;
+ if last_field_offset_byte > value.len() {
+ return Err(ArrowError::InvalidArgumentError(format!(
Review Comment:
Filed as https://github.com/apache/arrow-rs/issues/7681
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