RFR: 8365675: Add String Unicode Case-Folding Support [v7]

[Xueming Shen]

On Fri, 7 Nov 2025 22:14:51 GMT, Roger Riggs <rriggs at openjdk.org> wrote:

>> Xueming Shen has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   update to use value long for folding
>
> src/java.base/share/classes/jdk/internal/lang/CaseFolding.java.template line 169:
> 
>> 167:     private static final int HASH_NEXT = 2;
>> 168: 
>> 169:     private static int[][] hashKeys(int[] keys) {
> 
> It may be worthwhile to round up the hash modulo to a prime number to avoid unfortunate hash collisions.

I did try several prime numbers. It doesn’t really help because the code points in the table are mostly sequential within one continuous category range; if there’s a hash collision, using a different prime will likely just move the collision to the next code point.

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PR Review Comment: https://git.openjdk.org/jdk/pull/27628#discussion_r2516418571