[Fixes #2349] Support for JDK 14

Added the ability to parse and pretty-print the new 'x instanceof String y' pattern concept.
Added a test to the pretty printer to confirm that it works.

4 files changed, 30 insertions, 2 deletions

diff --git a/doc/changelog.markdown b/doc/changelog.markdown
index 8c1b463d..0407f1e3 100644
--- a/doc/changelog.markdown
+++ b/doc/changelog.markdown
@@ -3,6 +3,7 @@ Lombok Changelog
 
 ### v1.18.11 "Edgy Guinea Pig"
 * PLATFORM: Support for JDK13 (including `yield` in switch expressions, as well as delombok having a nicer style for arrow-style switch blocks, and text blocks).
+* PLATFORM: Support for JDK14 (including `pattern match` instanceof expressions).
 * FEATURE: In [`lombok.config`](https://projectlombok.org/features/configuration) it is possible to import other config files, even from a `.zip` or `.jar`.
 * FEATURE: You can now configure a builder's 'setter' prefixes via `@Builder(setterPrefix = "set")` for example. We discourage doing this, but if some library you use requires them, have at it. [Pull Request #2174](https://github.com/rzwitserloot/lombok/pull/2174], [Issue #1805](https://github.com/rzwitserloot/lombok/issues/1805).
 * FEATURE: If you use `@Builder`'s `@Singular`, a plural form is also generated, which has the effect of adding all elements in the passed collection. If you pass a null reference, this would result in a message-less `NullPointerException`. Now, it results in that exception but with a useful message attached, and you can choose other behaviors as well via a parameter on the `@Singular` annotation and via `lombok.config`; you can even choose treat them as empty collections; this can be useful when deserializing (e.g. Jackson JSON) and JPA/Hibernate code. [Issue #2221](https://github.com/rzwitserloot/lombok/issues/2221]. [singular documentation](https://projectlombok.org/features/Builder).
diff --git a/src/delombok/lombok/delombok/PrettyPrinter.java b/src/delombok/lombok/delombok/PrettyPrinter.java
index fc5eaec2..2db70f7f 100644
--- a/src/delombok/lombok/delombok/PrettyPrinter.java
+++ b/src/delombok/lombok/delombok/PrettyPrinter.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2016-2019 The Project Lombok Authors.
+ * Copyright (C) 2016-2020 The Project Lombok Authors.
  * 
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -1071,7 +1071,11 @@ public class PrettyPrinter extends JCTree.Visitor {
 	@Override public void visitTypeTest(JCInstanceOf tree) {
 		print(tree.expr);
 		print(" instanceof ");
-		print(tree.clazz);
+		
+		/** With java14, instead of a type (field 'clazz'), there's now a pattern (field 'pattern', of type JCTree, which is either a JCPattern for new-style instanceof, or if not it's the same as what 'clazz' held) */
+		JCTree c = readObject(tree, "clazz", null); // JDK-13
+		if (c == null) c = readObject(tree, "pattern", null); // JDK14+
+		print(c);
 	}
 	
 	@Override public void visitTypeCast(JCTypeCast tree) {
@@ -1379,6 +1383,12 @@ public class PrettyPrinter extends JCTree.Visitor {
 		println(";", tree);
 	}
 	
+	void printBindingPattern(JCTree tree) {
+		print((JCExpression) readObject(tree, "vartype", null));
+		print(" ");
+		print((Name) readObject(tree, "name", null));
+	}
+	
 	@Override public void visitTry(JCTry tree) {
 		aPrint("try ");
 		List<?> resources = readObject(tree, "resources", List.nil());
@@ -1601,6 +1611,8 @@ public class PrettyPrinter extends JCTree.Visitor {
 			printSwitchExpression(tree);
 		} else if ("JCYield".equals(simpleName)) { // Introduced as preview feature in JDK13, part of switch expressions.
 			printYieldExpression(tree);
+		} else if ("JCBindingPattern".equals(simpleName)) { // Introduced as preview in JDK14
+			printBindingPattern(tree);
 		} else {
 			throw new AssertionError("Unhandled tree type: " + tree.getClass() + ": " + tree);
 		}
diff --git a/test/pretty/resource/after/PatternInstanceOf.java b/test/pretty/resource/after/PatternInstanceOf.java
new file mode 100644
index 00000000..3fcba749
--- /dev/null
+++ b/test/pretty/resource/after/PatternInstanceOf.java
@@ -0,0 +1,7 @@
+public class PatternInstanceOf {
+	public void foo(Object o) {
+		if (o instanceof String y) {
+			System.out.println(y);
+		}
+	}
+}
diff --git a/test/pretty/resource/before/PatternInstanceOf.java b/test/pretty/resource/before/PatternInstanceOf.java
new file mode 100644
index 00000000..c957adeb
--- /dev/null
+++ b/test/pretty/resource/before/PatternInstanceOf.java
@@ -0,0 +1,8 @@
+// version 14:
+public class PatternInstanceOf {
+	public void foo(Object o) {
+		if (o instanceof String y) {
+			System.out.println(y);
+		}
+	}
+}