goel-skd commented on code in PR #760:
URL: https://github.com/apache/iceberg-cpp/pull/760#discussion_r3464444572
##########
src/iceberg/util/string_util.h:
##########
@@ -41,22 +40,24 @@ concept FromChars = requires(const char* p, T& v) {
std::from_chars(p, p, v); };
class ICEBERG_EXPORT StringUtils {
public:
- // NOTE: These convert ASCII letters only; all other bytes, including
non-ASCII
- // (multibyte UTF-8) bytes, are passed through unchanged.
- // See https://github.com/apache/iceberg-cpp/issues/613.
- static std::string ToLower(std::string_view str) {
- return str | std::ranges::views::transform(ToLowerAscii) |
- std::ranges::to<std::string>();
- }
-
+ /// \brief Lower-case a UTF-8 string using Unicode simple case mapping.
+ ///
+ /// Mirrors Iceberg Java's case-insensitive handling, which lower-cases
names with
+ /// toLowerCase(Locale.ROOT). Invalid UTF-8 input is returned unchanged.
+ /// See https://github.com/apache/iceberg-cpp/issues/613.
+ static std::string ToLower(std::string_view str);
+
+ /// \brief Upper-case ASCII letters; non-ASCII (multibyte UTF-8) bytes pass
through
+ /// unchanged.
+ ///
+ /// Unlike ToLower this is ASCII-only, since upper-casing is not used for
name matching.
Review Comment:
ASCII is a subset of UTF-8, so the UTF-8 ```ToLower``` is already correct on
ASCII input. A ```ToLowerAscii``` wouldn't be more correct, only faster on
known-ASCII data, and it makes the caller decide "is my input ASCII?", which is
sort of a foot-gun. One ToLower also matches Iceberg Java, which only has
toLowerCase(Locale.ROOT) with no ascii/utf8 split.
I suggest that we skip ```ToUpperUtf8``` either way. Simple-mapping
uppercase is just wrong for things like ß (stays ß, should be SS), and nothing
here uppercases non-ASCII anyway. The two ```ToUpper``` callers just normalize
codec/mode strings to match GZIP/ALL.
You're right it's misleading though. I'll rename ```ToUpper ->
ToUpperAscii``` so it's in the name, and keep ```ToLower``` as the Unicode one.
WDYT?
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