RFR: 8343829: Unify decimal and hexadecimal parsing in FloatingDecimal [v9]

[Chen Liang]

On Fri, 9 May 2025 22:48:34 GMT, Raffaello Giulietti <rgiulietti at openjdk.org> wrote:

>> See the JBS bug for some details.
>
> Raffaello Giulietti has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 14 additional commits since the last revision:
> 
>  - Removed useless comment.
>  - Merge branch 'master' into 8343829
>  - Added javadoc to refer to the grammar in j.l.Double.
>  - Merge branch 'master' into 8343829
>  - Make some static arrays @Stable.
>  - Remove unused BIG_DECIMAL_EXPONENT
>  - Merge branch 'master' into 8343829
>  - Merge branch 'master' into 8343829
>  - Redacted comments.
>  - Merge branch 'master' into 8343829
>  - ... and 4 more: https://git.openjdk.org/jdk/compare/e0e999c4...88fe2c08

Took a look over the string parsing part. Not professional enough about floating numbers.

src/java.base/share/classes/jdk/internal/math/FloatingDecimal.java line 1964:

> 1962: 
> 1963:         /* Skip opt [FfDd]? suffix. */
> 1964:         if (i < len && (((ch = in.charAt(i) | 0b10_0000)) == 'f' || ch == 'd')) {

Is it really right to ignore these suffix for all ix values?

src/java.base/share/classes/jdk/internal/math/FloatingDecimal.java line 2006:

> 2004:          *
> 2005:          *         |lz            |pt |tnz  |stop
> 2006:          * 0000000012345600000023.4567000000000

Suggestion:

         *         |lz            |pt |tnz     |stop
         * 0000000012345600000023.4567000000000

src/java.base/share/classes/jdk/internal/math/FloatingDecimal.java line 2265:

> 2263: 
> 2264:     /* Arithmetically "appends the digit" ch to v >= 0, clamping at 10^10. */
> 2265:     private static long appendDigit(long v, int ch) {

Since this appends only decimal digit, should we name it `appendDecDegit`? In the use site we already note all exponents are decimals.

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PR Review: https://git.openjdk.org/jdk/pull/22737#pullrequestreview-2829815281
PR Review Comment: https://git.openjdk.org/jdk/pull/22737#discussion_r2082593368
PR Review Comment: https://git.openjdk.org/jdk/pull/22737#discussion_r2082588752
PR Review Comment: https://git.openjdk.org/jdk/pull/22737#discussion_r2082592192