RFR: 8364007: Add no-argument codePointCount method to CharSequence and String [v3]

[Tatsunori Uchino]

On Sat, 26 Jul 2025 10:10:40 GMT, Tatsunori Uchino <duke at openjdk.org> wrote:

>> Adds `codePointCount()` overloads to `String`, `Character`, `(Abstract)StringBuilder`, and `StringBuffer` to make it possible to conveniently retrieve the length of a string as code points without extra boundary checks.
>> 
>> 
>> if (superTremendouslyLongExpressionYieldingAString().codePointCount() > limit) {
>>     throw new Exception("exceeding length");
>> }
>> 
>> 
>> Is a CSR required to this change?
>
> Tatsunori Uchino has updated the pull request incrementally with four additional commits since the last revision:
> 
>  - Update `@bug` in correct file
>  - Add default implementation on codePointCount in CharSequence
>  - Update `@bug` entries in test class doc comments
>  - Discard changes on code whose form is not `str.codePointCount(0, str.length())`

Its author may have prioritized the versatility of the APIs.

> `codePointCount(0, length())`

This workaround is only effective if the instance expression is sufficiently short or can afford to be stored to a new temporary variable once. It can be a pain in the neck that you have to write the expression even twice to get the number of code points in the entire string instance.

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PR Comment: https://git.openjdk.org/jdk/pull/26461#issuecomment-3148429115