RFR: 8282274: Compiler implementation for Pattern Matching for switch (Third Preview) [v11]
Jan Lahoda
jlahoda at openjdk.java.net
Thu May 12 10:54:16 UTC 2022
> This is a (preliminary) patch for javac implementation for the third preview of pattern matching for switch (type patterns in switches).
>
> Draft JLS:
> http://cr.openjdk.java.net/~gbierman/PatternSwitchPlusRecordPatterns/PatternSwitchPlusRecordPatterns-20220407/specs/patterns-switch-jls.html
>
> The changes are:
> -there are no guarded patterns anymore, guards are not bound to the CaseElement (JLS 15.28)
> -a new contextual keyword `when` is used to add a guard, instead of `&&`
> -`null` selector value is handled on switch level (if a switch has `case null`, it is used, otherwise a NPE is thrown), rather than on pattern matching level.
> -total patterns are allowed in `instanceof`
> -`java.lang.MatchException` is added for the case where a switch is exhaustive (due to sealed types) at compile-time, but not at runtime.
>
> Feedback is welcome!
>
> Thanks!
Jan Lahoda has updated the pull request incrementally with two additional commits since the last revision:
- Updating naming to more closely follow the spec: total patterns are renamed to unconditional patterns, unrefined is now unguarded.
- Case label elements cannot be unguarded if they have a guard of a type different than boolean.
-------------
Changes:
- all: https://git.openjdk.java.net/jdk/pull/8182/files
- new: https://git.openjdk.java.net/jdk/pull/8182/files/1101ad46..b0fb8dcd
Webrevs:
- full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8182&range=10
- incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8182&range=09-10
Stats: 247 lines in 12 files changed: 126 ins; 73 del; 48 mod
Patch: https://git.openjdk.java.net/jdk/pull/8182.diff
Fetch: git fetch https://git.openjdk.java.net/jdk pull/8182/head:pull/8182
PR: https://git.openjdk.java.net/jdk/pull/8182
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