Add instanceof statement (#10)

Author: biboudis

src/jdk.compiler/share/classes/com/sun/source/tree/InstanceOfStatementTree.java

@@ -0,0 +1,40 @@
+package com.sun.source.tree;
+
+import jdk.internal.javac.PreviewFeature;
+
+/**
+ * A tree node for an {@code instanceof} statement.
+ *
+ * For example:
+ * <pre>
+ *   <em>expression</em> instanceof <em>record pattern</em>;
+ * </pre>
+ *
+ * @jls 14.22 The {@code instanceof} Statement
+ *
+ * @author Aggelos Biboudis
+ * @since 23
+ */
+public interface InstanceOfStatementTree extends StatementTree {
+    /**
+     * Returns the pattern for the {@code instanceof} statement.
+     * @return pattern
+     */
+    @PreviewFeature(feature=PreviewFeature.Feature.PATTERN_DECLARATIONS, reflective=true)
+    Tree getPattern();
+
+    /**
+     * Returns the expression to be pattern matched.
+     * @return the expression
+     */
+    @PreviewFeature(feature=PreviewFeature.Feature.PATTERN_DECLARATIONS, reflective=true)
+    ExpressionTree getExpression();
+
+    /**
+     * Returns the type for which to check.
+     * @return the type
+     * @see #getPattern()
+     */
+    @PreviewFeature(feature=PreviewFeature.Feature.PATTERN_DECLARATIONS, reflective=true)
+    Tree getType();
+}

src/jdk.compiler/share/classes/com/sun/source/tree/Tree.java

@@ -175,6 +175,14 @@ public enum Kind {
          */
         INSTANCE_OF(InstanceOfTree.class),
 
+        /**
+         * Used for instances of {@link InstanceOfStatementTree}.
+         *
+         * @since 23
+         */
+        @PreviewFeature(feature=PreviewFeature.Feature.PATTERN_DECLARATIONS, reflective=true)
+        INSTANCEOF_STATEMENT(InstanceOfStatementTree.class),
+
         /**
          * Used for instances of {@link LabeledStatementTree}.
          */

src/jdk.compiler/share/classes/com/sun/source/tree/TreeVisitor.java

@@ -514,6 +514,14 @@ public interface TreeVisitor<R,P> {
      */
     R visitInstanceOf(InstanceOfTree node, P p);
 
+    /**
+     * Visits an {@code InstanceOfStatementTree} node.
+     * @param node the node being visited
+     * @param p a parameter value
+     * @return a result value
+     */
+    R visitInstanceOfStatement(InstanceOfStatementTree node, P p);
+
     /**
      * Visits a {@code UnaryTree} node.
      * @param node the node being visited

src/jdk.compiler/share/classes/com/sun/source/util/SimpleTreeVisitor.java

@@ -629,6 +629,20 @@ public R visitInstanceOf(InstanceOfTree node, P p) {
         return defaultAction(node, p);
     }
 
+    /**
+     * {@inheritDoc}
+     *
+     * @implSpec This implementation calls {@code defaultAction}.
+     *
+     * @param node {@inheritDoc}
+     * @param p {@inheritDoc}
+     * @return  the result of {@code defaultAction}
+     */
+    @Override
+    public R visitInstanceOfStatement(InstanceOfStatementTree node, P p) {
+        return defaultAction(node, p);
+    }
+
     /**
      * {@inheritDoc}
      *
@@ -1070,4 +1084,6 @@ public R visitYield(YieldTree node, P p) {
     public R visitMatchStatement(MatchTree node, P p) {
         return defaultAction(node, p);
     }
+
+
 }

src/jdk.compiler/share/classes/com/sun/source/util/TreeScanner.java

@@ -762,6 +762,22 @@ public R visitInstanceOf(InstanceOfTree node, P p) {
         return r;
     }
 
+    /**
+     * {@inheritDoc}
+     *
+     * @implSpec This implementation scans the children in left to right order.
+     *
+     * @param node  {@inheritDoc}
+     * @param p  {@inheritDoc}
+     * @return the result of scanning
+     */
+    @Override
+    public R visitInstanceOfStatement(InstanceOfStatementTree node, P p) {
+        R r = scan(node.getPattern(), p);
+        r = scanAndReduce(node.getExpression(), p, r);
+        return r;
+    }
+
     /**
      * {@inheritDoc}
      *

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Attr.java

@@ -2439,6 +2439,19 @@ public void visitMatch(JCMatch tree) {
         result = null;
     }
 
+    public void visitTypeTestStatement(JCInstanceOfStatement tree) {
+        attribExpr(tree.expr, env);
+        attribExpr(tree.pattern, env);
+
+        matchBindings.bindingsWhenTrue.forEach(env.info.scope::enter);
+        matchBindings.bindingsWhenTrue.forEach(BindingSymbol::preserveBinding);
+
+        Type clazztype = tree.pattern.type;
+        checkCastablePattern(tree.expr.pos(), tree.expr.type, clazztype);
+
+        result = null;
+    }
+
     public void visitContinue(JCContinue tree) {
         tree.target = findJumpTarget(tree.pos(), tree.getTag(), tree.label, env);
         result = null;

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Flow.java

@@ -696,6 +696,34 @@ public void visitMatch(JCMatch tree) {
             recordExit(new PendingExit(tree));
         }
 
+        public void visitTypeTestStatement(JCInstanceOfStatement tree) {
+            ListBuffer<PendingExit> prevPendingExits = pendingExits;
+            pendingExits = new ListBuffer<>();
+
+            if (tree.pattern instanceof JCRecordPattern rp) {
+                visitRecordPattern(rp);
+            }
+
+            List<JCCase> singletonCaseList = List.of(make.Case(
+                    CaseTree.CaseKind.STATEMENT,
+                    List.of(make.PatternCaseLabel(tree.pattern)),
+                    null,
+                    List.nil(),
+                    null)
+            );
+
+            boolean isExhaustive =
+                    exhausts(tree.expr, singletonCaseList);
+
+            if (!isExhaustive) {
+                log.error(tree, Errors.NotExhaustiveStatement); // TODO replace with instanceof-related error since this refers to switch
+            }
+
+            scan(tree.expr);
+
+            alive = alive.or(resolveBreaks(tree, prevPendingExits));
+        }
+
         public void visitForeachLoop(JCEnhancedForLoop tree) {
             visitVarDef(tree.var);
             ListBuffer<PendingExit> prevPendingExits = pendingExits;

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TransPatterns.java

@@ -56,6 +56,8 @@
 import com.sun.tools.javac.tree.JCTree.JCIdent;
 import com.sun.tools.javac.tree.JCTree.JCIf;
 import com.sun.tools.javac.tree.JCTree.JCInstanceOf;
+import com.sun.tools.javac.tree.JCTree.JCInstanceOfStatement;
+import com.sun.tools.javac.tree.JCTree.JCThrow;
 import com.sun.tools.javac.tree.JCTree.JCMethodDecl;
 import com.sun.tools.javac.tree.JCTree.JCSwitch;
 import com.sun.tools.javac.tree.JCTree.JCMatch;
@@ -266,6 +268,44 @@ public void visitTypeTest(JCInstanceOf tree) {
         }
     }
 
+    @Override
+    public void visitTypeTestStatement(JCInstanceOfStatement tree) {
+        /**
+         * A statement of the form
+         *
+         * <pre>
+         *     <expression> instanceof <pattern>;
+         * </pre>
+         *
+         * (where <pattern> is any pattern) is translated to:
+         *
+         * <pre>{@code
+         *     if (!(<expression> instanceof(<pattern>)) {
+         *         throw new MatchException(null, null);
+         *     }
+         * }</pre>
+         *
+         */
+        bindingContext = new BasicBindingContext();
+        try {
+            List<JCExpression> matchExParams = List.of(makeNull(), makeNull());
+            JCThrow thr = make.Throw(makeNewClass(syms.matchExceptionType, matchExParams));
+
+            JCExpression expr = translate(tree.expr);
+
+            JCInstanceOf instanceOfTree = make.TypeTest(expr, tree.pattern);
+            tree.type = syms.booleanType;
+
+            JCIf ifNode = make.If(makeUnary(Tag.NOT,
+                    translate(instanceOfTree)).setType(syms.booleanType), thr, null);
+
+            result = bindingContext.decorateStatement(ifNode);
+        } finally {
+            bindingContext.pop();
+        }
+    }
+
+
     @Override
     public void visitAnyPattern(JCTree.JCAnyPattern that) {
         result = make.Literal(true);

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TransTypes.java

@@ -1078,6 +1078,12 @@ public void visitTypeTest(JCInstanceOf tree) {
         result = tree;
     }
 
+    public void visitTypeTestStatement(JCInstanceOfStatement tree) {
+        tree.expr = translate(tree.expr, null);
+        tree.pattern = translate(tree.pattern, null);
+        result = tree;
+    }
+
     public void visitIndexed(JCArrayAccess tree) {
         tree.indexed = translate(tree.indexed, erasure(tree.indexed.type));
         tree.index = translate(tree.index, syms.intType);

src/jdk.compiler/share/classes/com/sun/tools/javac/parser/JavacParser.java

@@ -33,6 +33,7 @@
 import javax.lang.model.SourceVersion;
 
 import com.sun.source.tree.CaseTree;
+import com.sun.source.tree.InstanceOfStatementTree;
 import com.sun.source.tree.MemberReferenceTree.ReferenceMode;
 import com.sun.source.tree.ModuleTree.ModuleKind;
 
@@ -3016,11 +3017,17 @@ List<JCStatement> blockStatement() {
                 F.at(pos);
                 return localVariableDeclarations(mods, t, dc);
             } else {
-                // This Exec is an "ExpressionStatement"; it subsumes the terminating semicolon
-                t = checkExprStat(t);
-                accept(SEMI);
-                JCExpressionStatement expr = toP(F.at(pos).Exec(t));
-                return List.of(expr);
+                if (t.getTag() == TYPETEST && allowPatternDeclarations) {
+                    t = term2Rest(t, TreeInfo.orPrec);
+                    accept(SEMI);
+                    return List.of(toP(F.at(pos).TypeTestStatement(((JCInstanceOf) t).expr, ((JCInstanceOf)t ).getPattern())));
+                } else {
+                    // This Exec is an "ExpressionStatement"; it subsumes the terminating semicolon
+                    t = checkExprStat(t);
+                    accept(SEMI);
+                    JCExpressionStatement expr = toP(F.at(pos).Exec(t));
+                    return List.of(expr);
+                }
             }
         }
     }