alamb commented on code in PR #7911:
URL: https://github.com/apache/arrow-rs/pull/7911#discussion_r2202913815
##########
parquet-variant-compute/src/variant_array_builder.rs:
##########
@@ -168,7 +166,105 @@ impl VariantArrayBuilder {
self.value_buffer.extend_from_slice(value);
}
- // TODO: Return a Variant builder that will write to the underlying
buffers (TODO)
+ /// Return a DirectVariantBuilder that writes directly to the buffers of
this builder.
+ pub fn variant_builder(&mut self) -> DirectVariantBuilder {
+ // append directly into the metadata and value buffers
+ let metadata_buffer = std::mem::take(&mut self.metadata_buffer);
+ let value_buffer = std::mem::take(&mut self.value_buffer);
+ let metadata_offset = metadata_buffer.len();
+ let value_offset = value_buffer.len();
+ DirectVariantBuilder {
+ finished: false,
+ metadata_offset,
+ value_offset,
+ variant_builder: VariantBuilder::new_with_buffers(metadata_buffer,
value_buffer),
+ array_builder: self,
+ }
+ }
+}
+
+/// A `VariantBuilder` that writes directly to the buffers of a
`VariantArrayBuilder`.
+///
+/// See [`VariantArray::variant_builder`] for an example
+pub struct DirectVariantBuilder<'a> {
+ /// was finish called?
+ finished: bool,
+ /// starting metadata offset
+ metadata_offset: usize,
+ /// starting value offset
+ value_offset: usize,
+ array_builder: &'a mut VariantArrayBuilder,
+ variant_builder: VariantBuilder,
+}
+
+impl DirectVariantBuilder<'_> {
+ /// Return a reference to the underlying `VariantBuilder`
+ pub fn inner(&self) -> &VariantBuilder {
+ &self.variant_builder
+ }
+
+ /// Return a mutable reference to the underlying `VariantBuilder`
+ pub fn inner_mut(&mut self) -> &mut VariantBuilder {
+ &mut self.variant_builder
+ }
+
+ /// Called to finalize the variant and write it to the underlying buffers
+ ///
+ /// Note if you do not call finish, the struct will be reset and the
buffers
+ /// will not be updated.
+ ///
+ pub fn finish(mut self) {
+ let metadata_offset = self.metadata_offset;
+ let value_offset = self.value_offset;
+
+ // get the buffers back
+ let (metadata_buffer, value_buffer) = std::mem::take(&mut
self.variant_builder).finish();
Review Comment:
I implemented the `VariantBuilderExt` and it looks good.
The lifetimes get a little wonky, so I still needed to allow access to the
underlying builder. But maybe I can figure that out as a follwo on PR
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: github-unsubscr...@arrow.apache.org
For queries about this service, please contact Infrastructure at:
us...@infra.apache.org
