perf: walk unedited chunks line by line when generating mappings - #339
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antfu merged 2 commits intoSep 10, 2026
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…-lines # Conflicts: # src/utils/Mappings.ts
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Generating mappings for unedited chunks no longer visits every character, which makes
generateMapabout 3x faster on the benchmark (generateMap (no edit)1,912 -> 5,617 hz,generateDecodedMap (edit)2,197 -> 7,354 hz;hires: trueunchanged, it is bound by segment allocation).Without
hiresonly line starts and explicitaddSourcemapLocationpositions produce segments, soaddUneditedChunkjumps between newlines and reads those positions from the BitSet words. Thehiresmodes keep the per-character loop but test word characters by char code instead of a regex. Mappings are byte-identical across the test suite and a comparison harness (CRLF, unicode, empty inputs, every edit method).