8024415: Bug in javac Pretty: Wrong precedence in JCConditional trees
Summary: Fixed precedence and associativity issues with pretty printing of JCConditional expressions.
Reviewed-by: jfranck
Contributed-by: Andreas Lundblad <andreas.lundblad@oracle.com>, Matthew Dempsky <mdempsky@google.com>
--- a/langtools/src/share/classes/com/sun/tools/javac/tree/Pretty.java Mon Oct 07 16:51:56 2013 -0700
+++ b/langtools/src/share/classes/com/sun/tools/javac/tree/Pretty.java Tue Oct 08 15:33:28 2013 +0200
@@ -782,9 +782,9 @@
public void visitConditional(JCConditional tree) {
try {
open(prec, TreeInfo.condPrec);
- printExpr(tree.cond, TreeInfo.condPrec);
+ printExpr(tree.cond, TreeInfo.condPrec + 1);
print(" ? ");
- printExpr(tree.truepart, TreeInfo.condPrec);
+ printExpr(tree.truepart);
print(" : ");
printExpr(tree.falsepart, TreeInfo.condPrec);
close(prec, TreeInfo.condPrec);
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/test/tools/javac/tree/T8024415.java Tue Oct 08 15:33:28 2013 +0200
@@ -0,0 +1,113 @@
+/*
+ * Copyright (c) 2013, 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.
+ *
+ * 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.
+ */
+
+/*
+ * @test
+ * @bug 8024415
+ * @summary Pretty printing of JCConditional does not follow the precedence and
+ * associativity rules of JCConditional
+ * @run testng T8024415
+ */
+
+
+import static org.testng.Assert.assertEquals;
+
+import java.io.IOException;
+import java.io.StringWriter;
+
+import org.testng.annotations.Test;
+
+import com.sun.tools.javac.file.JavacFileManager;
+import com.sun.tools.javac.tree.JCTree;
+import com.sun.tools.javac.tree.JCTree.JCExpression;
+import com.sun.tools.javac.tree.Pretty;
+import com.sun.tools.javac.tree.TreeMaker;
+import com.sun.tools.javac.util.Context;
+import com.sun.tools.javac.util.Names;
+
+
+/*
+ * Test verifies that the precedence rules of conditional expressions
+ * (JCConditional) are correct.
+ */
+@Test
+public class T8024415 {
+
+ TreeMaker maker;
+ JCExpression x;
+
+
+ public T8024415() {
+ Context ctx = new Context();
+ JavacFileManager.preRegister(ctx);
+ maker = TreeMaker.instance(ctx);
+ Names names = Names.instance(ctx);
+ x = maker.Ident(names.fromString("x"));
+ }
+
+
+ // JLS 15.25: The conditional operator is syntactically right-associative
+ // (it groups right-to-left). Thus, a?b:c?d:e?f:g means the same as
+ // a?b:(c?d:(e?f:g)).
+ public void testAssociativity() throws IOException {
+
+ JCTree left = maker.Conditional(maker.Conditional(x, x, x), x, x);
+ JCTree right = maker.Conditional(x, x, maker.Conditional(x, x, x));
+
+ String prettyLeft = prettyPrint(left);
+ String prettyRight = prettyPrint(right);
+
+ assertEquals(prettyLeft.replaceAll("\\s", ""), "(x?x:x)?x:x");
+ assertEquals(prettyRight.replaceAll("\\s", ""), "x?x:x?x:x");
+
+ }
+
+
+ // The true-part of of a conditional expression is surrounded by ? and :
+ // and can thus always be parsed unambiguously without surrounding
+ // parentheses.
+ public void testPrecedence() throws IOException {
+
+ JCTree left = maker.Conditional(maker.Assign(x, x), x, x);
+ JCTree middle = maker.Conditional(x, maker.Assign(x, x), x);
+ JCTree right = maker.Conditional(x, x, maker.Assign(x, x));
+
+ String prettyLeft = prettyPrint(left);
+ String prettyMiddle = prettyPrint(middle);
+ String prettyRight = prettyPrint(right);
+
+ assertEquals(prettyLeft.replaceAll("\\s", ""), "(x=x)?x:x");
+ assertEquals(prettyMiddle.replaceAll("\\s", ""), "x?x=x:x");
+ assertEquals(prettyRight.replaceAll("\\s", ""), "x?x:(x=x)");
+
+ }
+
+
+ // Helper method
+ private static String prettyPrint(JCTree tree) throws IOException {
+ StringWriter sw = new StringWriter();
+ new Pretty(sw, true).printExpr(tree);
+ return sw.toString();
+ }
+
+}