On Sat, 22 Jul 2023 12:13:10 GMT, Cristian Vat <[email protected]> wrote:
>> Reduces excessive allocation of Matcher.groups array when the original
>> Pattern has no groups or less than 9 groups.
>>
>> Original clamping to 10 possibly due to documented behavior from javadoc:
>> "In this class, \1 through \9 are always interpreted as back references, "
>>
>> Only with Matcher changes RegExTest.backRefTest fails when backreferences to
>> non-existing groups are present.
>> Added a match failure condition in Pattern that fixes failing tests.
>>
>> As per existing `java.util.regex.Pattern.BackRef#match`: "// If the
>> referenced group didn't match, neither can this"
>>
>> A group that does not exist in the original Pattern can never match so
>> neither can a backref to that group.
>> If the group existed in the original Pattern then it would have had space
>> allocated in Matcher.groups for that group index.
>> So a group index outside groups array length must never match.
>
> Cristian Vat has updated the pull request incrementally with one additional
> commit since the last revision:
>
> reduce allocations also for Matcher.usePattern
Shouldn't the similar change be in `CIBackRef.match` too? The fact current
tests do not catch it makes me uneasy: the test coverage seems to be rather low
there.
We need a regex expert to look at it. @rgiulietti @igraves might help us out
here?
src/java.base/share/classes/java/util/regex/Pattern.java line 5190:
> 5188: }
> 5189: boolean match(Matcher matcher, int i, CharSequence seq) {
> 5190:
Excess new line.
-------------
PR Review: https://git.openjdk.org/jdk/pull/14894#pullrequestreview-1551614576
PR Review Comment: https://git.openjdk.org/jdk/pull/14894#discussion_r1277261871
