--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/test/tools/javac/plugin/showtype/ShowTypePlugin.java	Mon Nov 19 11:38:49 2012 -0800
@@ -0,0 +1,106 @@
+/*
+ * Copyright (c) 2012, 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.
+ */
+
+import com.sun.source.tree.CompilationUnitTree;
+import com.sun.source.tree.IdentifierTree;
+import com.sun.source.tree.MemberSelectTree;
+import com.sun.source.tree.Tree;
+import com.sun.source.util.JavacTask;
+import com.sun.source.util.Plugin;
+import com.sun.source.util.TaskEvent;
+import com.sun.source.util.TaskListener;
+import com.sun.source.util.TreePathScanner;
+import com.sun.source.util.Trees;
+import java.util.regex.Pattern;
+import javax.lang.model.type.TypeMirror;
+import javax.tools.Diagnostic.Kind;
+
+public class ShowTypePlugin implements Plugin {
+
+    public String getName() {
+        return "showtype";
+    }
+
+    public void call(JavacTask task, String... args) {
+        Pattern pattern = null;
+        if (args.length == 1)
+            pattern = Pattern.compile(args[0]);
+        task.addTaskListener(new PostAnalyzeTaskListener(task, pattern));
+    }
+
+    private static class PostAnalyzeTaskListener implements TaskListener {
+        private final ShowTypeTreeVisitor visitor;
+
+        PostAnalyzeTaskListener(JavacTask task, Pattern pattern) {
+            visitor = new ShowTypeTreeVisitor(task, pattern);
+        }
+
+        @Override
+        public void started(TaskEvent taskEvent) { }
+
+        @Override
+        public void finished(TaskEvent taskEvent) {
+            if (taskEvent.getKind().equals(TaskEvent.Kind.ANALYZE)) {
+                CompilationUnitTree compilationUnit = taskEvent.getCompilationUnit();
+                visitor.scan(compilationUnit, null);
+            }
+        }
+    }
+
+    private static class ShowTypeTreeVisitor extends TreePathScanner<Void, Void> {
+        private final Trees trees;
+        private final Pattern pattern;
+        private CompilationUnitTree currCompUnit;
+
+        ShowTypeTreeVisitor(JavacTask task, Pattern pattern) {
+            trees = Trees.instance(task);
+            this.pattern = pattern;
+        }
+
+        @Override
+        public Void visitCompilationUnit(CompilationUnitTree tree, Void ignore) {
+            currCompUnit = tree;
+            return super.visitCompilationUnit(tree, ignore);
+        }
+
+        @Override
+        public Void visitIdentifier(IdentifierTree tree, Void ignore) {
+            show(tree, tree.getName());
+            return super.visitIdentifier(tree, ignore);
+        }
+
+        @Override
+        public Void visitMemberSelect(MemberSelectTree tree, Void ignore) {
+            show(tree, tree.getIdentifier());
+            return super.visitMemberSelect(tree, ignore);
+        }
+
+        void show(Tree tree, CharSequence name) {
+            if (pattern == null || pattern.matcher(name).matches()) {
+                TypeMirror type = trees.getTypeMirror(getCurrentPath());
+                trees.printMessage(Kind.NOTE, "type is " + type, tree, currCompUnit);
+            }
+        }
+    }
+
+}