On Tue, 12 Apr 2022 13:18:14 GMT, Jan Lahoda <jlah...@openjdk.org> wrote:
>> 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 one additional > commit since the last revision: > > Cleanup. Looks good - I like how moving the guard from pattern to an expression inside a switch made the code simpler to reason about, and also simplified the compiler API. I left some comments in the javadoc of MatchException. src/java.base/share/classes/java/lang/MatchException.java line 33: > 31: * Thrown to indicate an unexpected failure in pattern matching. > 32: * > 33: * MatchException may be thrown when an exhaustive pattern matching > language construct Maybe wrap with `{@code}` src/java.base/share/classes/java/lang/MatchException.java line 34: > 32: * > 33: * MatchException may be thrown when an exhaustive pattern matching > language construct > 34: * (such as a switch expression) encounters a match target that does not > match any of the provided Is the term "match target" defined somewhere? In general, it would be good quoting relevant sections of the JLS, and using consistent terminology src/java.base/share/classes/java/lang/MatchException.java line 37: > 35: * patterns at runtime. This can currently arise from the following case: > 36: * <ul> > 37: * <li>Separate compilation anomalies, where a sealed interface has a > different Why a list if there's only one case? I know we have plans to expand this to cover nulls in records patterns, but right now the javadoc should stand on its own src/java.base/share/classes/java/lang/MatchException.java line 52: > 50: > 51: /** > 52: * Constructs an {@code MatchException} with no detail message. double space before "message" ? src/java.base/share/classes/java/lang/MatchException.java line 73: > 71: * > 72: * @param cause the cause (which is saved for later retrieval by the > 73: * {@link #getCause()} method). (A {@code null} value is double space before "(A" ? src/java.base/share/classes/java/lang/MatchException.java line 88: > 86: * by the {@link #getMessage()} method). > 87: * @param cause the cause (which is saved for later retrieval by the > 88: * {@link #getCause()} method). (A {@code null} value is Same here, double space before "(A" ------------- PR: https://git.openjdk.java.net/jdk/pull/8182
