[api] Add SourceFile line mapping methods#4420
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Pull request overview
Adds line/character mapping helpers to the native-preview SourceFile API surface to close #4215, enabling consumers to convert between UTF-16 positions and { line, character } pairs.
Changes:
- Introduces
LineAndCharacterand addsgetLineStarts,getLineAndCharacterOfPosition, andgetPositionOfLineAndCharacterto theSourceFileinterface. - Implements these methods on
RemoteSourceFile, including a cached line-starts array and a binary search for position-to-line mapping. - Adds encoder round-trip tests covering line starts, UTF-16 semantics, and line/character ↔ position conversion.
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.
| File | Description |
|---|---|
| _packages/native-preview/test/encoder.test.ts | Adds tests validating line start computation, UTF-16 line/character mapping, caching, and round-tripping. |
| _packages/native-preview/src/ast/ast.ts | Extends the public AST types with LineAndCharacter and new SourceFile mapping APIs. |
| _packages/native-preview/src/api/node/node.ts | Implements the new mapping APIs on RemoteSourceFile using computeLineStarts + binary search. |
Comment on lines
+212
to
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| getLineAndCharacterOfPosition(position: number): LineAndCharacter { | ||
| const lineStarts = this.getLineStarts(); | ||
| const line = computeLineOfPosition(lineStarts, position); | ||
| return { line, character: position - lineStarts[line] }; | ||
| } |
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The Strada implementation doesn't guard, so I think it's fine as-is
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| getPositionOfLineAndCharacter(line: number, character: number): number { | ||
| const lineStarts = this.getLineStarts(); | ||
| if (line < 0 || line >= lineStarts.length) { | ||
| throw new Error(`Bad line number. Line: ${line}, lineStarts.length: ${lineStarts.length}`); | ||
| } | ||
| return lineStarts[line] + character; | ||
| } |
jakebailey
approved these changes
Jun 23, 2026
github-merge-queue
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removed this pull request from the merge queue due to a conflict with the base branch
jakebailey
approved these changes
Jun 23, 2026
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Closes #4215