RFR: 8132995: Matcher$ImmutableMatchResult should be optimized to reduce space usage [v3]

[Claes Redestad]

On Wed, 17 May 2023 09:19:10 GMT, Raffaello Giulietti <rgiulietti at openjdk.org> wrote:

>> When appropriate and useful, copies only the relevant portion of the `CharSequence` to the match result.
>
> 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 five additional commits since the last revision:
> 
>  - Adjusted incorrect logic in results().
>    Added tests for results().
>    Refined capturing logic when there's no match.
>  - Merge branch 'master' into JDK-8132995
>  - Adjusted erroneous logic in results().
>    Added tests for results().
>  - Added some randomness in tests.
>  - 8132995: Matcher should be optimized to reduce space usage

LGTM. 

Consider simplifying `text instanceof String s ? s.substring(first, last) : text.subSequence(first, last).toString()` to just `text.subSequence(first, last).toString()`

src/java.base/share/classes/java/util/regex/Matcher.java line 278:

> 276:     public MatchResult toMatchResult() {
> 277:         String capturedText = hasMatch()
> 278:                 ? text instanceof String s

This `instanceof` became a little gratuitous now since `text.subSequence(..)` on `String` delegates to `substring` and the `toString()` will be a no-op.

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Marked as reviewed by redestad (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/13231#pullrequestreview-1430876173
PR Review Comment: https://git.openjdk.org/jdk/pull/13231#discussion_r1196633626