7115046: Add AST node for lambda expressions

Summary: Add tree nodes for representing lambda expressions and update relevant visitors interfaces
Reviewed-by: jjg

src/share/classes/com/sun/source/tree/LambdaExpressionTree.java

+/*
+ * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package com.sun.source.tree;
+
+import java.util.List;
+
+/**
+ * A tree node for a lambda expression.
+ *
+ * For example:
+ * <pre>
+ *   ()->{}
+ *   (List<String> ls)->ls.size()
+ *   (x,y)-> { return x + y; }
+ * </pre>
+ */
+public interface LambdaExpressionTree extends ExpressionTree {
+
+    /**
+     * Lambda expressions come in two forms: (i) expression lambdas, whose body
+     * is an expression, and (ii) statement lambdas, whose body is a block
+     */
+    public enum BodyKind {
+        /** enum constant for expression lambdas */
+        EXPRESSION,
+        /** enum constant for statement lambdas */
+        STATEMENT;
+    }
+
+    List<? extends VariableTree> getParameters();
+    Tree getBody();
+    BodyKind getBodyKind();
+}

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

@@ -186,6 +186,11 @@ public interface Tree {
          */
         NEW_CLASS(NewClassTree.class),
 
+        /**
+         * Used for instances of {@link LambdaExpressionTree}.
+         */
+        LAMBDA_EXPRESSION(LambdaExpressionTree.class),
+
         /**
          * Used for instances of {@link ParenthesizedTree}.
          */

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

@@ -85,6 +85,7 @@ public interface TreeVisitor<R,P> {
     R visitModifiers(ModifiersTree node, P p);
     R visitNewArray(NewArrayTree node, P p);
     R visitNewClass(NewClassTree node, P p);
+    R visitLambdaExpression(LambdaExpressionTree node, P p);
     R visitParenthesized(ParenthesizedTree node, P p);
     R visitReturn(ReturnTree node, P p);
     R visitMemberSelect(MemberSelectTree node, P p);

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

@@ -172,6 +172,10 @@ public class SimpleTreeVisitor <R,P> implements TreeVisitor<R,P> {
         return defaultAction(node, p);
     }
 
+    public R visitLambdaExpression(LambdaExpressionTree node, P p) {
+        return defaultAction(node, p);
+    }
+
     public R visitParenthesized(ParenthesizedTree node, P p) {
         return defaultAction(node, p);
     }

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

@@ -285,6 +285,12 @@ public class TreeScanner<R,P> implements TreeVisitor<R,P> {
         return r;
     }
 
+    public R visitLambdaExpression(LambdaExpressionTree node, P p) {
+        R r = scan(node.getParameters(), p);
+        r = scanAndReduce(node.getBody(), p, r);
+        return r;
+    }
+
     public R visitParenthesized(ParenthesizedTree node, P p) {
         return scan(node.getExpression(), p);
     }

src/share/classes/com/sun/tools/javac/tree/JCTree.java

@@ -41,6 +41,7 @@ import com.sun.tools.javac.code.Scope.*;
 import com.sun.tools.javac.code.Symbol.*;
 import com.sun.tools.javac.parser.EndPosTable;
 import com.sun.source.tree.*;
+import com.sun.source.tree.LambdaExpressionTree.BodyKind;
 
 import static com.sun.tools.javac.code.BoundKind.*;
 import static com.sun.tools.javac.tree.JCTree.Tag.*;
@@ -198,6 +199,10 @@ public abstract class JCTree implements Tree, Cloneable, DiagnosticPosition {
          */
         NEWARRAY,
 
+        /** Lambda expression, of type Lambda.
+         */
+        LAMBDA,
+
         /** Parenthesized subexpressions, of type Parens.
          */
         PARENS,
@@ -1486,6 +1491,56 @@ public abstract class JCTree implements Tree, Cloneable, DiagnosticPosition {
         }
     }
 
+    /**
+     * A lambda expression.
+     */
+    public static class JCLambda extends JCExpression implements LambdaExpressionTree {
+
+        public List<JCVariableDecl> params;
+        public JCTree body;
+        public Type targetType;
+        public boolean canCompleteNormally = true;
+        public List<Type> inferredThrownTypes;
+
+        public JCLambda(List<JCVariableDecl> params,
+                        JCTree body) {
+            this.params = params;
+            this.body = body;
+        }
+        @Override
+        public Tag getTag() {
+            return LAMBDA;
+        }
+        @Override
+        public void accept(Visitor v) {
+            v.visitLambda(this);
+        }
+        @Override
+        public <R, D> R accept(TreeVisitor<R, D> v, D d) {
+            return v.visitLambdaExpression(this, d);
+        }
+        public Kind getKind() {
+            return Kind.LAMBDA_EXPRESSION;
+        }
+        public JCTree getBody() {
+            return body;
+        }
+        public java.util.List<? extends VariableTree> getParameters() {
+            return params;
+        }
+        @Override
+        public JCLambda setType(Type type) {
+            super.setType(type);
+            return this;
+        }
+        @Override
+        public BodyKind getBodyKind() {
+            return body.hasTag(BLOCK) ?
+                    BodyKind.STATEMENT :
+                    BodyKind.EXPRESSION;
+        }
+    }
+
     /**
      * A parenthesized subexpression ( ... )
      */
@@ -2271,6 +2326,7 @@ public abstract class JCTree implements Tree, Cloneable, DiagnosticPosition {
         public void visitApply(JCMethodInvocation that)      { visitTree(that); }
         public void visitNewClass(JCNewClass that)           { visitTree(that); }
         public void visitNewArray(JCNewArray that)           { visitTree(that); }
+        public void visitLambda(JCLambda that)               { visitTree(that); }
         public void visitParens(JCParens that)               { visitTree(that); }
         public void visitAssign(JCAssign that)               { visitTree(that); }
         public void visitAssignop(JCAssignOp that)           { visitTree(that); }

src/share/classes/com/sun/tools/javac/tree/Pretty.java

@@ -907,6 +907,17 @@ public class Pretty extends JCTree.Visitor {
         }
     }
 
+    public void visitLambda(JCLambda tree) {
+        try {
+            print("(");
+            printExprs(tree.params);
+            print(")->");
+            printExpr(tree.body);
+        } catch (IOException e) {
+            throw new UncheckedIOException(e);
+        }
+    }
+
     public void visitParens(JCParens tree) {
         try {
             print("(");

src/share/classes/com/sun/tools/javac/tree/TreeCopier.java

@@ -271,6 +271,13 @@ public class TreeCopier<P> implements TreeVisitor<JCTree,P> {
         return M.at(t.pos).NewClass(encl, typeargs, clazz, args, def);
     }
 
+    public JCTree visitLambdaExpression(LambdaExpressionTree node, P p) {
+        JCLambda t = (JCLambda) node;
+        List<JCVariableDecl> params = copy(t.params, p);
+        JCTree body = copy(t.body, p);
+        return M.at(t.pos).Lambda(params, body);
+    }
+
     public JCTree visitParenthesized(ParenthesizedTree node, P p) {
         JCParens t = (JCParens) node;
         JCExpression expr = copy(t.expr, p);

src/share/classes/com/sun/tools/javac/tree/TreeMaker.java

@@ -351,6 +351,14 @@ public class TreeMaker implements JCTree.Factory {
         return tree;
     }
 
+    public JCLambda Lambda(List<JCVariableDecl> params,
+                           JCTree body)
+    {
+        JCLambda tree = new JCLambda(params, body);
+        tree.pos = pos;
+        return tree;
+    }
+
     public JCParens Parens(JCExpression expr) {
         JCParens tree = new JCParens(expr);
         tree.pos = pos;

src/share/classes/com/sun/tools/javac/tree/TreeScanner.java

@@ -212,6 +212,11 @@ public class TreeScanner extends Visitor {
         scan(tree.elems);
     }
 
+    public void visitLambda(JCLambda tree) {
+        scan(tree.body);
+        scan(tree.params);
+    }
+
     public void visitParens(JCParens tree) {
         scan(tree.expr);
     }

src/share/classes/com/sun/tools/javac/tree/TreeTranslator.java

@@ -282,6 +282,12 @@ public class TreeTranslator extends JCTree.Visitor {
         result = tree;
     }
 
+    public void visitLambda(JCLambda tree) {
+        tree.params = translate(tree.params);
+        tree.body = translate(tree.body);
+        result = tree;
+    }
+
     public void visitNewArray(JCNewArray tree) {
         tree.elemtype = translate(tree.elemtype);
         tree.dims = translate(tree.dims);