codephage2020 commented on code in PR #7934:
URL: https://github.com/apache/arrow-rs/pull/7934#discussion_r2212012414
##########
parquet-variant/src/variant/object.rs:
##########
@@ -217,23 +217,31 @@ impl<'m, 'v> VariantObject<'m, 'v> {
self.header.field_ids_start_byte() as
_..self.first_field_offset_byte as _,
)?;
- let field_ids = map_bytes_to_offsets(field_id_buffer,
self.header.field_id_size)
- .collect::<Vec<_>>();
-
+ let mut field_ids_iter =
+ map_bytes_to_offsets(field_id_buffer,
self.header.field_id_size);
// Validate all field ids exist in the metadata dictionary and the
corresponding field names are lexicographically sorted
if self.metadata.is_sorted() {
// Since the metadata dictionary has unique and sorted field
names, we can also guarantee this object's field names
// are lexicographically sorted by their field id ordering
- if !field_ids.is_sorted() {
- return Err(ArrowError::InvalidArgumentError(
- "field names not sorted".to_string(),
- ));
- }
+ let dictionary_size = self.metadata.dictionary_size();
+
+ if let Some(mut current_id) = field_ids_iter.next() {
+ for next_id in field_ids_iter {
+ if current_id >= dictionary_size {
+ return Err(ArrowError::InvalidArgumentError(
+ "field id is not valid".to_string(),
+ ));
+ }
+
+ if next_id <= current_id {
+ return Err(ArrowError::InvalidArgumentError(
+ "field names not sorted".to_string(),
+ ));
+ }
+ current_id = next_id;
+ }
- // Since field ids are sorted, if the last field is smaller
than the dictionary size,
- // we also know all field ids are smaller than the dictionary
size and in-bounds.
- if let Some(&last_field_id) = field_ids.last() {
- if last_field_id >= self.metadata.dictionary_size() {
+ if current_id >= dictionary_size {
Review Comment:
Sorry, I didn't expect this to be confusing. This loop has considered many
ways of writing, and in the end, I referred to
https://github.com/apache/arrow-rs/blob/main/parquet-variant/src/variant/list.rs#L225-L232.
I think this is an elegant implementation. Perhaps I need to add comments or
use the following writing style to make the code more readable.
```rust
let mut previous_id: Option<u32> = None;
for field_id in field_ids_iter {
if field_id >= dictionary_size {
return Err(ArrowError::InvalidArgumentError(
"field id is not valid".to_string(),
));
}
if let Some(prev_id) = previous_id {
if field_id <= prev_id {
return Err(ArrowError::InvalidArgumentError(
"field names not sorted".to_string(),
));
}
}
previous_id = Some(field_id);
}
```
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