moonbitlang / core / 4850

91%

Build Type

push

github

Committed by web-flow

Commit Message

perf(strconv): skip underscore validation scan when none present (#3708)

`parse_double` calls `check_underscore` on every input to validate
underscore placement. That scan walks the whole string with a
multi-arm match over `StringView` slices -- each `.. rest` materializes
a new view and churns reference counts -- even though the vast majority
of numeric inputs contain no underscore at all.

Without any underscore the validation can never fail: every `break
false` arm requires a preceding underscore. Probe the raw code units
once with `contains_code_unit` (a tight loop with no sub-view
allocation) and skip the match loop entirely in that case.

Bench (parse_double, n=4096, native):
  fast digits:  137.8 µs -> 107.4 µs  (~22% faster)
  underscores:  170.1 µs -> 170.5 µs  (unchanged)

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Coverage Stats

1 of 1 new or added line in 1 file covered. (100.0%)

1 existing line in 1 file now uncovered.

15221 of 16673 relevant lines covered (91.29%)

197065.44 hits per line