minor: refactor array reverse internals#18445
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Jefffrey merged 1 commit intoapache:mainfrom Nov 3, 2025
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Jefffrey
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Nov 2, 2025
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| fn general_array_reverse<O: OffsetSizeTrait + TryFrom<i64>>( | ||
| fn general_array_reverse<O: OffsetSizeTrait>( |
| OffsetBuffer::<O>::new(offsets.into()), | ||
| arrow::array::make_array(data), | ||
| Some(nulls.into()), | ||
| array.nulls().cloned(), |
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We can directly copy the nulls from the input array instead of recreating it step by step (do the same for fixed size lists below)
| MutableArrayData::with_capacities(vec![&original_data], false, capacity); | ||
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| for (row_index, offset_window) in array.offsets().windows(2).enumerate() { | ||
| for (row_index, (&start, &end)) in array.offsets().iter().tuple_windows().enumerate() |
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Using tuple_windows from itertools for a nicer interface on grabbing the start & end indices
| nulls.push(false); | ||
| offsets.push(offsets[row_index] + O::one()); | ||
| mutable.extend(0, 0, 1); | ||
| offsets.push(offsets[row_index]); |
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We can just have an empty list here since it's null anyway, instead of extending the child array by one element
| let end = offset_window[1]; | ||
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| let mut index = end - O::one(); | ||
| let mut cnt = 0; |
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cnt can be determined once up front
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Nice! |
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## Which issue does this PR close? <!-- We generally require a GitHub issue to be filed for all bug fixes and enhancements and this helps us generate change logs for our releases. You can link an issue to this PR using the GitHub syntax. For example `Closes apache#123` indicates that this PR will close issue apache#123. --> N/A ## Rationale for this change <!-- Why are you proposing this change? If this is already explained clearly in the issue then this section is not needed. Explaining clearly why changes are proposed helps reviewers understand your changes and offer better suggestions for fixes. --> When reviewing apache#18424 I noticed some refactoring that could be applied to existing array reverse implementation. ## What changes are included in this PR? <!-- There is no need to duplicate the description in the issue here but it is sometimes worth providing a summary of the individual changes in this PR. --> ## Are these changes tested? <!-- We typically require tests for all PRs in order to: 1. Prevent the code from being accidentally broken by subsequent changes 2. Serve as another way to document the expected behavior of the code If tests are not included in your PR, please explain why (for example, are they covered by existing tests)? --> See my comments for the refactors & justifications. Existing tests. ## Are there any user-facing changes? <!-- If there are user-facing changes then we may require documentation to be updated before approving the PR. --> No. <!-- If there are any breaking changes to public APIs, please add the `api change` label. -->
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Which issue does this PR close?
N/A
Rationale for this change
When reviewing #18424 I noticed some refactoring that could be applied to existing array reverse implementation.
What changes are included in this PR?
Are these changes tested?
See my comments for the refactors & justifications.
Existing tests.
Are there any user-facing changes?
No.