[JEP441] Add support for switch pattern matching #4375

johannescoetzee · 2024-04-18T10:25:52Z

Switch pattern matching changes introduced in https://openjdk.org/jeps/441

This PR adds support for switch pattern matching with guards and resolves #4343 using the approach discussed in #4361 and partially implemented in #4357.

In particular, it adds support for the new CasePattern [Guard] syntax in

SwitchLabel:
  case CaseConstant {, CaseConstant}
  case null [, default]
  case CasePattern [Guard]    // <- New support
  default

CasePattern:
  Pattern

Guard:
  when Expression

The main changes in this PR are:

Syntax support in the parser
Syntax support in the concrete syntax model
Addition of an optional SwitchEntry.guard field which contains the guard expression if any
Type solver checks switch pattern labels to find variable declarations
Fixes for the PrettyPrinter and LexicalPreservingPrinter
Some unit tests for all of the above.

johannescoetzee · 2024-04-18T10:26:42Z

...lization/src/test/java/com/github/javaparser/serialization/JavaParserJsonSerializerTest.java


        String serialized = serialize(cu, false);

-        assertEquals("{\"!\":\"com.github.javaparser.ast.CompilationUnit\",\"range\":{\"beginLine\":1,\"beginColumn\":1,\"endLine\":1,\"endColumn\":23},\"tokenRange\":{\"beginToken\":{\"kind\":19,\"text\":\"class\"},\"endToken\":{\"kind\":0,\"text\":\"\"}},\"imports\":[],\"types\":[{\"!\":\"com.github.javaparser.ast.body.ClassOrInterfaceDeclaration\",\"range\":{\"beginLine\":1,\"beginColumn\":1,\"endLine\":1,\"endColumn\":23},\"tokenRange\":{\"beginToken\":{\"kind\":19,\"text\":\"class\"},\"endToken\":{\"kind\":103,\"text\":\"}\"}},\"extendedTypes\":[],\"implementedTypes\":[],\"isInterface\":\"false\",\"permittedTypes\":[],\"typeParameters\":[],\"members\":[{\"!\":\"com.github.javaparser.ast.body.FieldDeclaration\",\"range\":{\"beginLine\":1,\"beginColumn\":9,\"endLine\":1,\"endColumn\":22},\"tokenRange\":{\"beginToken\":{\"kind\":97,\"text\":\"java\"},\"endToken\":{\"kind\":106,\"text\":\";\"}},\"modifiers\":[],\"variables\":[{\"!\":\"com.github.javaparser.ast.body.VariableDeclarator\",\"range\":{\"beginLine\":1,\"beginColumn\":21,\"endLine\":1,\"endColumn\":21},\"tokenRange\":{\"beginToken\":{\"kind\":97,\"text\":\"y\"},\"endToken\":{\"kind\":97,\"text\":\"y\"}},\"name\":{\"!\":\"com.github.javaparser.ast.expr.SimpleName\",\"range\":{\"beginLine\":1,\"beginColumn\":21,\"endLine\":1,\"endColumn\":21},\"tokenRange\":{\"beginToken\":{\"kind\":97,\"text\":\"y\"},\"endToken\":{\"kind\":97,\"text\":\"y\"}},\"identifier\":\"y\"},\"type\":{\"!\":\"com.github.javaparser.ast.type.ClassOrInterfaceType\",\"range\":{\"beginLine\":1,\"beginColumn\":9,\"endLine\":1,\"endColumn\":19},\"tokenRange\":{\"beginToken\":{\"kind\":97,\"text\":\"java\"},\"endToken\":{\"kind\":97,\"text\":\"Y\"}},\"name\":{\"!\":\"com.github.javaparser.ast.expr.SimpleName\",\"range\":{\"beginLine\":1,\"beginColumn\":19,\"endLine\":1,\"endColumn\":19},\"tokenRange\":{\"beginToken\":{\"kind\":97,\"text\":\"Y\"},\"endToken\":{\"kind\":97,\"text\":\"Y\"}},\"identifier\":\"Y\"},\"scope\":{\"!\":\"com.github.javaparser.ast.type.ClassOrInterfaceType\",\"range\":{\"beginLine\":1,\"beginColumn\":9,\"endLine\":1,\"endColumn\":17},\"tokenRange\":{\"beginToken\":{\"kind\":97,\"text\":\"java\"},\"endToken\":{\"kind\":97,\"text\":\"util\"}},\"name\":{\"!\":\"com.github.javaparser.ast.expr.SimpleName\",\"range\":{\"beginLine\":1,\"beginColumn\":14,\"endLine\":1,\"endColumn\":17},\"tokenRange\":{\"beginToken\":{\"kind\":97,\"text\":\"util\"},\"endToken\":{\"kind\":97,\"text\":\"util\"}},\"identifier\":\"util\"},\"scope\":{\"!\":\"com.github.javaparser.ast.type.ClassOrInterfaceType\",\"range\":{\"beginLine\":1,\"beginColumn\":9,\"endLine\":1,\"endColumn\":12},\"tokenRange\":{\"beginToken\":{\"kind\":97,\"text\":\"java\"},\"endToken\":{\"kind\":97,\"text\":\"java\"}},\"name\":{\"!\":\"com.github.javaparser.ast.expr.SimpleName\",\"range\":{\"beginLine\":1,\"beginColumn\":9,\"endLine\":1,\"endColumn\":12},\"tokenRange\":{\"beginToken\":{\"kind\":97,\"text\":\"java\"},\"endToken\":{\"kind\":97,\"text\":\"java\"}},\"identifier\":\"java\"},\"annotations\":[]},\"annotations\":[]},\"annotations\":[]}}],\"annotations\":[]}],\"modifiers\":[],\"name\":{\"!\":\"com.github.javaparser.ast.expr.SimpleName\",\"range\":{\"beginLine\":1,\"beginColumn\":7,\"endLine\":1,\"endColumn\":7},\"tokenRange\":{\"beginToken\":{\"kind\":97,\"text\":\"X\"},\"endToken\":{\"kind\":97,\"text\":\"X\"}},\"identifier\":\"X\"},\"annotations\":[]}]}", serialized);


The changes here are just some token kind values which changed due to the addition of the WHEN token

johannescoetzee · 2024-04-18T10:27:49Z

javaparser-core/src/main/java/com/github/javaparser/JavaToken.java

        EXPORTS(76),
        PROVIDES(77),
        TRANSITIVE(78),
-        LONG_LITERAL(79),


These changes are generated

johannescoetzee · 2024-04-18T10:28:01Z

javaparser-core/src/main/java/com/github/javaparser/JavaToken.java


        public static Kind valueOf(int kind) {
            switch(kind) {
-                case 150:


These changes are generated

codecov · 2024-04-18T10:56:07Z

Codecov Report

Attention: Patch coverage is 70.19868% with 45 lines in your changes are missing coverage. Please review.

Project coverage is 51.912%. Comparing base (9f532e5) to head (7df03e3).
Report is 2 commits behind head on master.

Additional details and impacted files

@@              Coverage Diff              @@
##            master     #4375       +/-   ##
=============================================
- Coverage   51.929%   51.912%   -0.018%     
=============================================
  Files          503       503               
  Lines        28369     28442       +73     
  Branches      4920      4934       +14     
=============================================
+ Hits         14732     14765       +33     
- Misses       11591     11625       +34     
- Partials      2046      2052        +6

Flag	Coverage Δ
AlsoSlowTests	`51.912% <70.198%> (-0.018%)`	⬇️
javaparser-core	`51.912% <70.198%> (-0.018%)`	⬇️
javaparser-symbol-solver	`51.912% <70.198%> (-0.018%)`	⬇️
jdk-10	`51.909% <70.198%> (-0.018%)`	⬇️
jdk-11	`51.909% <70.198%> (-0.018%)`	⬇️
jdk-12	`51.909% <70.198%> (-0.018%)`	⬇️
jdk-13	`51.909% <70.198%> (-0.007%)`	⬇️
jdk-14	`51.909% <70.198%> (-0.007%)`	⬇️
jdk-15	`51.909% <70.198%> (-0.018%)`	⬇️
jdk-16	`51.909% <70.198%> (-0.018%)`	⬇️
jdk-17	`51.909% <70.198%> (-0.018%)`	⬇️
jdk-18	`51.909% <70.198%> (-0.018%)`	⬇️
jdk-8	`51.907% <70.198%> (-0.018%)`	⬇️
jdk-9	`51.898% <70.198%> (-0.018%)`	⬇️
macos-latest	`51.905% <70.198%> (-0.018%)`	⬇️
ubuntu-latest	`51.895% <70.198%> (-0.018%)`	⬇️
windows-latest	`51.891% <70.198%> (-0.018%)`	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
...src/main/java/com/github/javaparser/JavaToken.java	`92.841% <100.000%> (+0.032%)`	⬆️
...rc/main/java/com/github/javaparser/TokenTypes.java	`84.615% <ø> (ø)`
...ub/javaparser/ast/observer/ObservableProperty.java	`88.953% <100.000%> (+0.064%)`	⬆️
...or/language_level_validations/Java21Validator.java	`100.000% <100.000%> (ø)`
...hub/javaparser/ast/visitor/VoidVisitorAdapter.java	`99.043% <100.000%> (+0.002%)`	⬆️
...thub/javaparser/metamodel/JavaParserMetaModel.java	`99.462% <100.000%> (+0.002%)`	⬆️
...hub/javaparser/metamodel/SwitchEntryMetaModel.java	`100.000% <ø> (ø)`
...github/javaparser/printer/ConcreteSyntaxModel.java	`94.957% <100.000%> (ø)`
...avaparser/printer/DefaultPrettyPrinterVisitor.java	`92.891% <100.000%> (+0.017%)`	⬆️
...r/language_level_validations/Java1_0Validator.java	`96.000% <80.000%> (-1.143%)`	⬇️
... and 11 more

... and 2 files with indirect coverage changes

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johannescoetzee · 2024-04-18T11:35:04Z

I just realized I forgot to update the validators. I'll update the PR with that probably this afternoon.

jlerbsc · 2024-04-18T13:25:17Z

javaparser-core/src/main/java/com/github/javaparser/ast/stmt/SwitchEntry.java

        if (node == null) {
            return false;
        }
+        if (guard != null) {


Why this and the counterpart?
Do you have a test case that tests the deletion of a node with a guard expression?

jlerbsc · 2024-04-18T13:28:06Z

javaparser-core/src/main/java/com/github/javaparser/ast/visitor/CloneVisitor.java

    @Override
    public Visitable visit(final InitializerDeclaration n, final Object arg) {
        BlockStmt body = cloneNode(n.getBody(), arg);
+        NodeList<AnnotationExpr> annotations = cloneList(n.getAnnotations(), arg);


How does this relate to the subject of the PR?

jlerbsc · 2024-04-18T13:32:21Z

javaparser-core/src/main/java/com/github/javaparser/ast/visitor/GenericVisitorAdapter.java

    @Override
    public R visit(final SwitchEntry n, final A arg) {
        R result;
+        if (n.getGuard().isPresent()) {


I don't understand this block!

jlerbsc · 2024-04-18T14:02:30Z

javaparser-core/src/main/java/com/github/javaparser/printer/ConcreteSyntaxModel.java

        concreteSyntaxModelByClass.put(ReturnStmt.class, sequence(comment(), token(GeneratedJavaParserConstants.RETURN), conditional(ObservableProperty.EXPRESSION, IS_PRESENT, sequence(space(), child(ObservableProperty.EXPRESSION))), semicolon()));
        concreteSyntaxModelByClass.put(YieldStmt.class, sequence(comment(), token(YIELD), conditional(ObservableProperty.EXPRESSION, IS_PRESENT, sequence(space(), child(ObservableProperty.EXPRESSION))), semicolon()));
-        concreteSyntaxModelByClass.put(SwitchEntry.class, sequence(comment(), conditional(SWITCH_STATEMENT_ENTRY, FLAG, conditional(ObservableProperty.LABELS, IS_NOT_EMPTY, sequence(token(GeneratedJavaParserConstants.CASE), space(), list(ObservableProperty.LABELS), token(GeneratedJavaParserConstants.COLON)), sequence(token(GeneratedJavaParserConstants._DEFAULT), token(GeneratedJavaParserConstants.COLON))), conditional(ObservableProperty.LABELS, IS_NOT_EMPTY, conditional(ObservableProperty.DEFAULT, FLAG, sequence(token(GeneratedJavaParserConstants.CASE), space(), list(ObservableProperty.LABELS), comma(), space(), token(GeneratedJavaParserConstants._DEFAULT), space(), token(GeneratedJavaParserConstants.ARROW)), sequence(token(GeneratedJavaParserConstants.CASE), space(), list(ObservableProperty.LABELS), token(GeneratedJavaParserConstants.ARROW))), sequence(token(GeneratedJavaParserConstants._DEFAULT), space(), token(GeneratedJavaParserConstants.ARROW)))), newline(), indent(), list(ObservableProperty.STATEMENTS, newline(), none(), newline()), unindent()));
+        concreteSyntaxModelByClass.put(SwitchEntry.class, sequence(comment(), conditional(SWITCH_STATEMENT_ENTRY, FLAG, conditional(ObservableProperty.LABELS, IS_NOT_EMPTY, sequence(token(GeneratedJavaParserConstants.CASE), space(), list(ObservableProperty.LABELS), token(GeneratedJavaParserConstants.COLON)), sequence(token(GeneratedJavaParserConstants._DEFAULT), token(GeneratedJavaParserConstants.COLON))), conditional(ObservableProperty.LABELS, IS_NOT_EMPTY, conditional(ObservableProperty.DEFAULT, FLAG, sequence(token(GeneratedJavaParserConstants.CASE), space(), list(ObservableProperty.LABELS), comma(), space(), token(GeneratedJavaParserConstants._DEFAULT), space(), token(GeneratedJavaParserConstants.ARROW)), sequence(token(GeneratedJavaParserConstants.CASE), space(), list(ObservableProperty.LABELS), conditional(ObservableProperty.GUARDED_ENTRY, FLAG, sequence(space(), token(GeneratedJavaParserConstants.WHEN), space(), child(ObservableProperty.GUARD))), space(), token(GeneratedJavaParserConstants.ARROW))), sequence(token(GeneratedJavaParserConstants._DEFAULT), space(), token(GeneratedJavaParserConstants.ARROW)))), newline(), indent(), list(ObservableProperty.STATEMENTS, newline(), none(), newline()), unindent()));


I'm not sure that the GUARDED_ENTRY property is necessary. Can't we just use the GUARD property?

jlerbsc · 2024-04-18T14:04:25Z

javaparser-core/src/main/java/com/github/javaparser/ast/stmt/SwitchEntry.java

+     * be expected or not.
+     */
+    @DerivedProperty
+    public boolean isGuardedEntry() {


I'm not sure that the GUARDED_ENTRY property is necessary. Can't we just use the GUARD property?

jlerbsc · 2024-04-18T14:07:39Z

Great work. I've got a few questions, but it seems fine to me, with the possible exception of the derived property introduced for the Lexical Preserving Printer.

< 6293 /task-lists>

johannescoetzee · 2024-04-19T16:24:58Z

I've updated this PR with the following:

Removed the GUARDED_ENTRY property in favour of using the IS_PRESENT condition on the GUARD
Updated validators with tests
Added removal tests

jlerbsc · 2024-04-19T16:41:06Z

A job well done. Thanks for your time.

pativa · 2024-05-29T12:19:28Z

This looks great and should resolve an issue we are facing with javaparser!

Do you have any estimate as of when this will be released? 🙏

jlerbsc · 2024-05-29T12:36:20Z

This will be integrated into the next release, which will provide support for all Java 21 non-preview features

Add support for switch pattern matching

2cd8281

johannescoetzee commented Apr 18, 2024

View reviewed changes

johannescoetzee added 2 commits April 18, 2024 12:35

Fix backwards compatible constructors

e6287f9

Remove unnecessary testcase

0837aca

Fix test so that it checks guard and body

7d61880

jlerbsc reviewed Apr 18, 2024

View reviewed changes

johannescoetzee added 3 commits April 19, 2024 10:57

Remove guarded_entry derived property

97ebbce

Add validators with tests, as well as remove tests

7e2e457

Merge branch 'master' into johannes/switch-patterns

7df03e3

jlerbsc merged commit 62794f1 into javaparser:master Apr 19, 2024

jlerbsc added this to the next release milestone Apr 19, 2024

jlerbsc added the PR: Added A PR that introduces new behaviour (e.g. functionality, tests) label Apr 19, 2024

johannescoetzee mentioned this pull request Apr 22, 2024

Record Patterns Implementation Proposal #4385

Closed

johannescoetzee mentioned this pull request May 2, 2024

Spotless formatting implementation proposal #4408

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[JEP441] Add support for switch pattern matching #4375

[JEP441] Add support for switch pattern matching #4375

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		String serialized = serialize(cu, false);

		assertEquals("{\"!\":\"com.github.javaparser.ast.CompilationUnit\",\"range\":{\"beginLine\":1,\"beginColumn\":1,\"endLine\":1,\"endColumn\":23},\"tokenRange\":{\"beginToken\":{\"kind\":19,\"text\":\"class\"},\"endToken\":{\"kind\":0,\"text\":\"\"}},\"imports\":[],\"types\":[{\"!\":\"com.github.javaparser.ast.body.ClassOrInterfaceDeclaration\",\"range\":{\"beginLine\":1,\"beginColumn\":1,\"endLine\":1,\"endColumn\":23},\"tokenRange\":{\"beginToken\":{\"kind\":19,\"text\":\"class\"},\"endToken\":{\"kind\":103,\"text\":\"}\"}},\"extendedTypes\":[],\"implementedTypes\":[],\"isInterface\":\"false\",\"permittedTypes\":[],\"typeParameters\":[],\"members\":[{\"!\":\"com.github.javaparser.ast.body.FieldDeclaration\",\"range\":{\"beginLine\":1,\"beginColumn\":9,\"endLine\":1,\"endColumn\":22},\"tokenRange\":{\"beginToken\":{\"kind\":97,\"text\":\"java\"},\"endToken\":{\"kind\":106,\"text\":\";\"}},\"modifiers\":[],\"variables\":[{\"!\":\"com.github.javaparser.ast.body.VariableDeclarator\",\"range\":{\"beginLine\":1,\"beginColumn\":21,\"endLine\":1,\"endColumn\":21},\"tokenRange\":{\"beginToken\":{\"kind\":97,\"text\":\"y\"},\"endToken\":{\"kind\":97,\"text\":\"y\"}},\"name\":{\"!\":\"com.github.javaparser.ast.expr.SimpleName\",\"range\":{\"beginLine\":1,\"beginColumn\":21,\"endLine\":1,\"endColumn\":21},\"tokenRange\":{\"beginToken\":{\"kind\":97,\"text\":\"y\"},\"endToken\":{\"kind\":97,\"text\":\"y\"}},\"identifier\":\"y\"},\"type\":{\"!\":\"com.github.javaparser.ast.type.ClassOrInterfaceType\",\"range\":{\"beginLine\":1,\"beginColumn\":9,\"endLine\":1,\"endColumn\":19},\"tokenRange\":{\"beginToken\":{\"kind\":97,\"text\":\"java\"},\"endToken\":{\"kind\":97,\"text\":\"Y\"}},\"name\":{\"!\":\"com.github.javaparser.ast.expr.SimpleName\",\"range\":{\"beginLine\":1,\"beginColumn\":19,\"endLine\":1,\"endColumn\":19},\"tokenRange\":{\"beginToken\":{\"kind\":97,\"text\":\"Y\"},\"endToken\":{\"kind\":97,\"text\":\"Y\"}},\"identifier\":\"Y\"},\"scope\":{\"!\":\"com.github.javaparser.ast.type.ClassOrInterfaceType\",\"range\":{\"beginLine\":1,\"beginColumn\":9,\"endLine\":1,\"endColumn\":17},\"tokenRange\":{\"beginToken\":{\"kind\":97,\"text\":\"java\"},\"endToken\":{\"kind\":97,\"text\":\"util\"}},\"name\":{\"!\":\"com.github.javaparser.ast.expr.SimpleName\",\"range\":{\"beginLine\":1,\"beginColumn\":14,\"endLine\":1,\"endColumn\":17},\"tokenRange\":{\"beginToken\":{\"kind\":97,\"text\":\"util\"},\"endToken\":{\"kind\":97,\"text\":\"util\"}},\"identifier\":\"util\"},\"scope\":{\"!\":\"com.github.javaparser.ast.type.ClassOrInterfaceType\",\"range\":{\"beginLine\":1,\"beginColumn\":9,\"endLine\":1,\"endColumn\":12},\"tokenRange\":{\"beginToken\":{\"kind\":97,\"text\":\"java\"},\"endToken\":{\"kind\":97,\"text\":\"java\"}},\"name\":{\"!\":\"com.github.javaparser.ast.expr.SimpleName\",\"range\":{\"beginLine\":1,\"beginColumn\":9,\"endLine\":1,\"endColumn\":12},\"tokenRange\":{\"beginToken\":{\"kind\":97,\"text\":\"java\"},\"endToken\":{\"kind\":97,\"text\":\"java\"}},\"identifier\":\"java\"},\"annotations\":[]},\"annotations\":[]},\"annotations\":[]}}],\"annotations\":[]}],\"modifiers\":[],\"name\":{\"!\":\"com.github.javaparser.ast.expr.SimpleName\",\"range\":{\"beginLine\":1,\"beginColumn\":7,\"endLine\":1,\"endColumn\":7},\"tokenRange\":{\"beginToken\":{\"kind\":97,\"text\":\"X\"},\"endToken\":{\"kind\":97,\"text\":\"X\"}},\"identifier\":\"X\"},\"annotations\":[]}]}", serialized);

[JEP441] Add support for switch pattern matching #4375

[JEP441] Add support for switch pattern matching #4375

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