[java] Add Java 13 support

Fix type resolution of switch with yields

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/ast/ASTYieldStatement.java

@@ -18,4 +18,13 @@ public class ASTYieldStatement extends AbstractJavaTypeNode {
     public Object jjtAccept(JavaParserVisitor visitor, Object data) {
         return visitor.visit(this, data);
     }
+
+    @Override
+    public String getImage() {
+        String result = super.getImage();
+        if (result == null && hasDescendantOfType(ASTName.class)) {
+            result = getFirstDescendantOfType(ASTName.class).getImage();
+        }
+        return result;
+    }
 }

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/typeresolution/ClassTypeResolver.java

@@ -34,7 +34,6 @@ import net.sourceforge.pmd.lang.java.ast.ASTArrayDimsAndInits;
 import net.sourceforge.pmd.lang.java.ast.ASTBlock;
 import net.sourceforge.pmd.lang.java.ast.ASTBlockStatement;
 import net.sourceforge.pmd.lang.java.ast.ASTBooleanLiteral;
-import net.sourceforge.pmd.lang.java.ast.ASTBreakStatement;
 import net.sourceforge.pmd.lang.java.ast.ASTCastExpression;
 import net.sourceforge.pmd.lang.java.ast.ASTClassOrInterfaceDeclaration;
 import net.sourceforge.pmd.lang.java.ast.ASTClassOrInterfaceType;
@@ -1187,7 +1186,7 @@ public class ClassTypeResolver extends JavaParserVisitorAdapter {
         super.visit(node, data);
 
         JavaTypeDefinition type = null;
-        // first try to determine the type based on the first expression/break of a switch rule
+        // first try to determine the type based on the first expression/break/yield of a switch rule
         List<ASTSwitchLabeledRule> rules = node.findChildrenOfType(ASTSwitchLabeledRule.class);
         for (ASTSwitchLabeledRule rule : rules) {
             Node body = rule.jjtGetChild(1); // second child is either Expression, Block, ThrowStatement
@@ -1203,10 +1202,18 @@ public class ClassTypeResolver extends JavaParserVisitorAdapter {
                         break;
                     }
                 }
+                List<ASTYieldStatement> yields = body.findDescendantsOfType(ASTYieldStatement.class);
+                if (!yields.isEmpty()) {
+                    ASTExpression expression = yields.get(0).getFirstChildOfType(ASTExpression.class);
+                    if (expression != null) {
+                        type = expression.getTypeDefinition();
+                        break;
+                    }
+                }
             }
         }
         if (type == null) {
-            // now check the labels and their expressions of break statements
+            // now check the labels and their expressions of break/yield statements
             for (int i = 0; i < node.jjtGetNumChildren(); i++) {
                 Node child = node.jjtGetChild(i);
                 if (child instanceof ASTBlockStatement) {
@@ -1218,6 +1225,14 @@ public class ClassTypeResolver extends JavaParserVisitorAdapter {
                             break;
                         }
                     }
+                    List<ASTYieldStatement> yields = child.findDescendantsOfType(ASTYieldStatement.class);
+                    if (!yields.isEmpty()) {
+                        ASTExpression expression = yields.get(0).getFirstChildOfType(ASTExpression.class);
+                        if (expression != null && expression.getTypeDefinition() != null) {
+                            type = expression.getTypeDefinition();
+                            break;
+                        }
+                    }
                 }
             }
         }

pmd-java/src/test/java/net/sourceforge/pmd/lang/java/ast/Java13Test.java

@@ -41,6 +41,29 @@ public class Java13Test {
         Assert.assertEquals(Integer.TYPE, yieldStatement.getType());
     }
 
+    @Test
+    public void testSwitchExpressionsYield() {
+        ASTCompilationUnit compilationUnit = ParserTstUtil.parseAndTypeResolveJava("13",
+                loadSource("SwitchExpressionsYield.java"));
+        Assert.assertNotNull(compilationUnit);
+
+        ASTSwitchExpression switchExpression = compilationUnit.getFirstDescendantOfType(ASTSwitchExpression.class);
+        Assert.assertEquals(11, switchExpression.jjtGetNumChildren());
+        Assert.assertTrue(switchExpression.jjtGetChild(0) instanceof ASTExpression);
+        Assert.assertEquals(5, switchExpression.findChildrenOfType(ASTSwitchLabel.class).size());
+
+        ASTYieldStatement yieldStatement = switchExpression.getFirstDescendantOfType(ASTYieldStatement.class);
+        Assert.assertEquals("SwitchExpressionsBreak.SIX", yieldStatement.getImage());
+        Assert.assertTrue(yieldStatement.jjtGetChild(0) instanceof ASTExpression);
+
+        ASTLocalVariableDeclaration localVar = compilationUnit.findDescendantsOfType(ASTLocalVariableDeclaration.class)
+                .get(1);
+        ASTVariableDeclarator localVarDecl = localVar.getFirstChildOfType(ASTVariableDeclarator.class);
+        Assert.assertEquals(Integer.TYPE, localVarDecl.getType());
+        Assert.assertEquals(Integer.TYPE, switchExpression.getType());
+    }
+
+
     @Test(expected = ParseException.class)
     public void testSwitchExpressionsBeforeJava13() {
         ParserTstUtil.parseAndTypeResolveJava("12", loadSource("SwitchExpressions.java"));

pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/ast/jdkversiontests/java13/SwitchExpressionsYield.java

@@ -0,0 +1,36 @@
+/**
+ * 
+ * @see <a href="https://openjdk.java.net/jeps/325">JEP 325: Switch Expressions (Preview)</a>
+ */
+public class SwitchExpressionsYield {
+    private static final int MONDAY = 1;
+    private static final int TUESDAY = 2;
+    private static final int WEDNESDAY = 3;
+    private static final int THURSDAY = 4;
+    private static final int FRIDAY = 5;
+    private static final int SATURDAY = 6;
+    private static final int SUNDAY = 7;
+
+    private static final int SIX = 6;
+
+    public static void main(String[] args) {
+        int day = FRIDAY;
+
+        var numLetters = switch (day) {
+                    case MONDAY, FRIDAY, SUNDAY: yield SwitchExpressionsBreak.SIX;
+                    case TUESDAY               : yield 7;
+                    case THURSDAY, SATURDAY    : yield 8;
+                    case WEDNESDAY             : yield 9;
+                    default                    : {
+                        int k = day * 2;
+                        int result = f(k);
+                        yield result;
+                    }
+                };
+        System.out.printf("NumLetters: %d%n", numLetters);
+    }
+
+    private static int f(int k) {
+        return k*3;
+    }
+}