perf(sorted_set): merge-walk symmetric_difference without intermediate sets#3819
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bobzhang wants to merge 1 commit into
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perf(sorted_set): merge-walk symmetric_difference without intermediate sets#3819bobzhang wants to merge 1 commit into
bobzhang wants to merge 1 commit into
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…e sets Resolves the TODO: symmetric_difference built two difference sets and then a union — five tree traversals, two full tree copies inside union, and a full recount of the result size. Replace it with a single in-order merge walk over both iterators, adding elements present in exactly one set. Set size stays correct because the result is built through `add`. Adds interleaved and proper-subset test cases to exercise both advance paths of the merge walk. Reviewed by Codex CLI (codex-cli 0.144.1): "No findings. Approved. The merge correctly emits the smaller head, skips equal heads, and drains either tail... add maintains size correctly." Signed-off-by: Codex CLI <codex@openai.com> Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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Coverage Report for CI Build 5181Coverage increased (+0.009%) to 91.277%Details
Uncovered ChangesNo uncovered changes found. Coverage RegressionsNo coverage regressions found. Coverage Stats
💛 - Coveralls |
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Resolves the
TODO: Optimize this function to avoid creating two intermediate setsinsorted_set/set.mbt.Before
symmetric_differencecomputedself.difference(other),other.difference(self), thenunioned them — roughly five tree traversals, two fullcopy_trees insideunion, plusunion's O(n+m) size-recount pass, all to produce one result set.After
A single in-order merge walk over both sets' pull iterators (
SortedSet::iteris an explicit-stack ascending traversal;Iter::nextis a consuming pull), adding elements present in exactly one set. No intermediate sets, no tree copies, one pass. Size bookkeeping stays correct because the result is built throughadd.Adds two test cases (interleaved elements, proper subset) to exercise both advance paths of the merge walk, alongside the existing basic/empty/identical coverage.
Review
Reviewed by Codex CLI (codex-cli 0.144.1): "No findings. Approved. The merge correctly emits the smaller head, skips equal heads, and drains either tail, preserving exact symmetric-difference semantics.
iteris ascending in-order;nextconsumes one pull.addmaintains size correctly."Signed-off-by: Codex CLI codex@openai.com
Validation
moon checkclean,moon fmtapplied, no.mbtichangesmoon test: 6717 passed, 0 failed (sorted_set 58/58, incl. 2 new)🤖 Generated with Claude Code