Add ArenaCompactTree::merge_zipper_into_file: append-only merge into an ACT file#53
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imlvts wants to merge 1 commit into
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Add ArenaCompactTree::merge_zipper_into_file: append-only merge into an ACT file#53imlvts wants to merge 1 commit into
imlvts wants to merge 1 commit into
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…an ACT file Merges any zipper (Zipper + ZipperMoving + ZipperValues) into an existing on-disk ACT by appending only the new data and rewriting the root offset; existing bytes are never modified. Backward relative offsets let appended nodes reference old subtrees directly, so untouched subtrees are shared byte-for-byte. Because siblings must be stored contiguously, a node with any changed child gets its sibling run re-emitted as shallow copies whose children still point into the old arena; line nodes are split as needed, reusing the old line data when a whole segment survives. On value conflicts the zipper's value wins, and a merge that adds nothing leaves the file untouched. Works with PathMap read zippers and ACT zippers alike (ACT -> ACT merge), enabling incremental accumulation into one ACT file without rebuilding it. Also fixes get_val_at reading past a branch's last sibling when asked for a byte absent from the child mask (missing test_bit check; subtract-overflow panic in debug builds). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Adam-Vandervorst
approved these changes
Jul 13, 2026
| } | ||
| if !node.bytemask.test_bit(path[0]) { | ||
| return None; | ||
| } |
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Do you have a regression case for this?
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This actually fixes a bug. prolly need to add a test case to showcase the bug.
| // Several merge waves over an LCG key soup; the last wave merges from | ||
| // an ACT zipper instead of a PathMap zipper. | ||
| let dir = tempfile::tempdir().unwrap(); | ||
| let file = dir.path().join("waves.act"); |
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The name doesn't matter much. It's a collection of randomly generated sequences.
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Maybe useful in other places; can keep it in the repo?
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Merges any zipper (Zipper + ZipperMoving + ZipperValues) into an existing on-disk ACT by appending only the new data and rewriting the root offset; existing bytes are never modified. Backward relative offsets let appended nodes reference old subtrees directly, so untouched subtrees are shared byte-for-byte. Because siblings must be stored contiguously, a node with any changed child gets its sibling run re-emitted as shallow copies whose children still point into the old arena; line nodes are split as needed, reusing the old line data when a whole segment survives. On value conflicts the zipper's value wins, and a merge that adds nothing leaves the file untouched.
Works with PathMap read zippers and ACT zippers alike (ACT -> ACT merge), enabling incremental accumulation into one ACT file without rebuilding it.
Also fixes get_val_at reading past a branch's last sibling when asked for a byte absent from the child mask (missing test_bit check; subtract-overflow panic in debug builds).