RFR: 8316704: Regex-free parsing of Formatter and FormatProcessor specifiers [v7]

[温绍锦]

On Mon, 25 Sep 2023 12:28:06 GMT, Claes Redestad <redestad at openjdk.org> wrote:

>> 温绍锦 has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   fix logic error
>
> src/java.base/share/classes/java/util/Formatter.java line 2949:
> 
>> 2947:                             }
>> 2948:                         } else {
>> 2949:                             if (first == '0') {
> 
> While it's clever to avoid re-parsing I think it muddies the control flow. It would be simpler if we always reset to `off = start; c = first` in this `else` block then unconditionally call `parseFlags(); parseWidth();` outside in `parse`. The few extra calls to `s.charAt(..)` this might add a little overhead on some tests, but the JIT might like the brevity and less branchy structure overall and on larger benchmarks.. Maybe worth experimenting with.

Good idea. In addition, I also plan to simplify the writing of the for statement, such as:

for (int size = 0; off < max; ++off, c = s.charAt(off), size++) {
==>
for (int size = 0; off < max; c = s.charAt(++off), size++) {

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PR Review Comment: https://git.openjdk.org/jdk/pull/15776#discussion_r1335909991