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stringutil: Handle properly acronyms in the CamelToSnakeCase #79

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Merged
AlexisMontagne merged 1 commit into from
Oct 29, 2025
Merged

stringutil: Handle properly acronyms in the CamelToSnakeCase #79

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12 changes: 8 additions & 4 deletions stringutil/camel_to_snake_case.go
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Original file line number Diff line number Diff line change
Expand Up @@ -5,11 +5,15 @@ import (
"strings"
)

var upperCase = regexp.MustCompile(`([A-Z]+)`)
var upperCaseRegexps = []*regexp.Regexp{
regexp.MustCompile(`([A-Z][a-z]+)`),
regexp.MustCompile(`([A-Z]+)`),
}

func CamelToSnakeCase(s string) string {
s = upperCase.ReplaceAllString(s, `_$1`)
s = strings.TrimPrefix(s, "_")
for _, re := range upperCaseRegexps {
s = re.ReplaceAllStringFunc(s, func(s string) string { return "_" + strings.ToLower(s) })
}

return strings.ToLower(s)
return strings.ToLower(strings.TrimPrefix(s, "_"))
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@cursor cursor bot Oct 28, 2025

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Bug: Regex Overlap Causes Double Underscore

The implementation introduces double underscores when an acronym is followed by a capitalized word. When the second regex ([A-Z]+) matches a sequence of uppercase letters that already has an underscore prefix from the first pass, it adds another underscore. For example, "WithAcronymLikeURL" becomes "with_acronym_like__url" instead of the expected "with_acronym_like_url" due to the double underscore before "url". The test case will fail because the actual output doesn't match the expected output.

Fix in Cursor Fix in Web

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@AlexisMontagne AlexisMontagne Oct 28, 2025

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say what? 🫨

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@xgoffin xgoffin Oct 29, 2025

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Bot is tired it seems :suspect:

}
2 changes: 2 additions & 0 deletions stringutil/camel_to_snake_case_test.go
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Expand Up @@ -12,6 +12,8 @@ func TestCamelToSnakeCase(t *testing.T) {
{"Camel", "camel"},
{"VeryVeryLongCamelCase", "very_very_long_camel_case"},
{"WithAcronymLikeURL", "with_acronym_like_url"},
{"CRMFetcher", "crm_fetcher"},
{"A0", "a0"},
} {
if out := CamelToSnakeCase(tt.in); tt.out != out {
t.Errorf("CamelToSnakeCase(%q) = %q wanted: %q", tt.in, out, tt.out)
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