add debugger

modules/lang-painless/build.gradle

@@ -29,6 +29,7 @@ dependencies {
   compile 'org.ow2.asm:asm:5.0.4'
   compile 'org.ow2.asm:asm-commons:5.0.4'
   compile 'org.ow2.asm:asm-tree:5.0.4'
+  testCompile 'org.ow2.asm:asm-util:5.0.4'
 }
 
 dependencyLicenses {

modules/lang-painless/src/main/java/org/elasticsearch/painless/Compiler.java

@@ -90,20 +90,23 @@ final class Compiler {
      * @return An {@link Executable} Painless script.
      */
     static Executable compile(final Loader loader, final String name, final String source, final CompilerSettings settings) {
+        final byte[] bytes = compile(name, source, Definition.INSTANCE, settings);
+        return createExecutable(loader, Definition.INSTANCE, name, source, bytes);
+    }
+
+    /**
+     * Compiles the script to bytecode
+     */
+    static byte[] compile(String name, String source, Definition definition, CompilerSettings settings) {
         if (source.length() > MAXIMUM_SOURCE_LENGTH) {
             throw new IllegalArgumentException("Scripts may be no longer than " + MAXIMUM_SOURCE_LENGTH +
-                " characters.  The passed in script is " + source.length() + " characters.  Consider using a" +
-                " plugin if a script longer than this length is a requirement.");
+                    " characters.  The passed in script is " + source.length() + " characters.  Consider using a" +
+                    " plugin if a script longer than this length is a requirement.");
         }
-
-        final Definition definition = Definition.INSTANCE;
         final ParserRuleContext root = createParseTree(source);
         final Metadata metadata = new Metadata(definition, source, root, settings);
         Analyzer.analyze(metadata);
-        final byte[] bytes = Writer.write(metadata);
-        final Executable executable = createExecutable(loader, definition, name, source, bytes);
-
-        return executable;
+        return Writer.write(metadata);
     }
 
     /**
@@ -140,17 +143,6 @@ final class Compiler {
     private static Executable createExecutable(final Loader loader, final Definition definition,
                                                final String name, final String source, final byte[] bytes) {
         try {
-            // Used for debugging.  Uncomment this code and add -Dtests.security.manager=false when running to save
-            // the generated Java class files.  The javap tool can then be used to inspect the generated byte code.
-
-            // try {
-            //    FileOutputStream f = new FileOutputStream(new File("<path>"), false);
-            //    f.write(bytes);
-            //    f.close();
-            // } catch (Exception e) {
-            //    throw new RuntimeException(e);
-            // }
-
             final Class<? extends Executable> clazz = loader.define(WriterConstants.CLASS_NAME, bytes);
             final java.lang.reflect.Constructor<? extends Executable> constructor =
                     clazz.getConstructor(Definition.class, String.class, String.class);

modules/lang-painless/src/test/java/org/elasticsearch/painless/Debugger.java

@@ -0,0 +1,53 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.painless;
+
+import org.objectweb.asm.ClassReader;
+import org.objectweb.asm.util.TraceClassVisitor;
+
+import java.io.ByteArrayOutputStream;
+import java.io.OutputStreamWriter;
+import java.io.PrintWriter;
+import java.io.UnsupportedEncodingException;
+import java.nio.charset.StandardCharsets;
+
+/** quick and dirty tools for debugging */
+final class Debugger {
+
+    /** compiles source to bytecode, and returns debugging output */
+    static String toString(String source) {
+        return toString(source, new CompilerSettings());
+    }
+
+    /** compiles to bytecode, and returns debugging output */
+    static String toString(String source, CompilerSettings settings) {
+        byte[] bytes = Compiler.compile("debugger", source, Definition.INSTANCE, settings);
+        ByteArrayOutputStream output = new ByteArrayOutputStream();
+        PrintWriter outputWriter = new PrintWriter(new OutputStreamWriter(output, StandardCharsets.UTF_8));
+        ClassReader reader = new ClassReader(bytes);
+        reader.accept(new TraceClassVisitor(outputWriter), 0);
+        outputWriter.flush();
+        try {
+            return output.toString("UTF-8");
+        } catch (UnsupportedEncodingException e) {
+            throw new RuntimeException(e);
+        }
+    }
+}