Source-order line diff
Compares rows in their current position. A moved function can appear as one large deletion followed by one large insertion.
Concept and worked evidence
Semantic code diff that keeps related code together
A semantic code diff uses program structure to reduce misleading delete-and-insert noise. AlignDiff pairs related functions, classes, methods, and other supported structures before showing detailed line changes.
Definition
What “semantic diff” means here
AlignDiff is structure-aware rather than a proof of behavioural equivalence. It parses supported source files, identifies named structures, proposes pairs, and then calculates the detailed text changes inside each pair.
That distinction matters: a structural match can show that two functions are likely counterparts after a move or rename, but it cannot prove that the refactor preserves runtime behaviour.
Line diff versus structure-aware diff
Movement and editing are different review questions
Structure-aware comparison
Pairs likely counterparts first. Movement remains visible, while edits inside the moved function can be reviewed in the same horizontal lane.
When it is useful
Use structural comparison when source order is hiding the real edit
Moved functions
Separate relocation from changes made inside the function.
Renamed structures
Inspect a likely rename without losing the corresponding body.
Large refactors
Reduce navigation cost when many blocks move in the same pull request.
Current boundaries
Useful evidence, not an automatic approval
- The browser beta currently supports Python, JavaScript, and
.tsTypeScript. - TSX, JSX, saved comparisons, accounts, and share links are not currently supported.
- Malformed or unsupported syntax can fall back to a bounded text comparison.
- Possible or incorrect pairings still require human review and can be adjusted manually.
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