--- a/src/jdk/nashorn/internal/runtime/Context.java	Thu Aug 22 17:23:50 2013 +0200
+++ b/src/jdk/nashorn/internal/runtime/Context.java	Thu Aug 22 13:51:24 2013 -0300
@@ -91,6 +91,11 @@
      */
     public static final String NASHORN_JAVA_REFLECTION = "nashorn.JavaReflection";
 
+    /* Force DebuggerSupport to be loaded. */
+    static {
+        DebuggerSupport.FORCELOAD = true;
+    }
+
     /**
      * ContextCodeInstaller that has the privilege of installing classes in the Context.
      * Can only be instantiated from inside the context and is opaque to other classes

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk/nashorn/internal/runtime/DebuggerSupport.java	Thu Aug 22 13:51:24 2013 -0300
@@ -0,0 +1,310 @@
+/*
+ * Copyright (c) 2010, 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  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  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  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 jdk.nashorn.internal.runtime;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * This class provides support for external debuggers.  Its primary purpose is
+ * is to simplify the debugger tasks and provide better performance.
+ */
+final class DebuggerSupport {
+    /**
+     * Hook to force the loading of the DebuggerSupport class so that it is
+     * available to external debuggers.
+     */
+    static boolean FORCELOAD = true;
+
+    static {
+        /**
+         * Hook to force the loading of the DebuggerValueDesc class so that it is
+         * available to external debuggers.
+         */
+        DebuggerValueDesc forceLoad = new DebuggerValueDesc(null, false, null, null);
+    }
+
+    /** This class is used to send a bulk description of a value. */
+    static class DebuggerValueDesc {
+        /** Property key (or index) or field name. */
+        final String key;
+
+        /** If the value is expandable. */
+        final boolean expandable;
+
+        /** Property or field value as object. */
+        final Object valueAsObject;
+
+        /** Property or field value as string. */
+        final String valueAsString;
+
+        DebuggerValueDesc(final String key, final boolean expandable, final Object valueAsObject, final String valueAsString) {
+            this.key           = key;
+            this.expandable    = expandable;
+            this.valueAsObject = valueAsObject;
+            this.valueAsString = valueAsString;
+        }
+    }
+
+    /**
+     * Return the current context global.
+     * @return context global.
+     */
+    static Object getGlobal() {
+        return Context.getGlobalTrusted();
+    }
+
+    /**
+     * This method returns a bulk description of an object's properties.
+     * @param object Script object to be displayed by the debugger.
+     * @param all    true if to include non-enumerable values.
+     * @return An array of DebuggerValueDesc.
+     */
+    static DebuggerValueDesc[] valueInfos(final Object object, final boolean all) {
+        assert object instanceof ScriptObject;
+        return getDebuggerValueDescs((ScriptObject)object, all, new HashSet<>());
+    }
+
+    /**
+     * This method returns a debugger description of the value.
+     * @param name  Name of value (property name).
+     * @param value Data value.
+     * @param all   true if to include non-enumerable values.
+     * @return A DebuggerValueDesc.
+     */
+    static DebuggerValueDesc valueInfo(final String name, final Object value, final boolean all) {
+        return valueInfo(name, value, all, new HashSet<>());
+    }
+
+   /**
+     * This method returns a debugger description of the value.
+     * @param name       Name of value (property name).
+     * @param value      Data value.
+     * @param all        true if to include non-enumerable values.
+     * @param duplicates Duplication set to avoid cycles.
+     * @return A DebuggerValueDesc.
+     */
+    private static DebuggerValueDesc valueInfo(final String name, final Object value, final boolean all, final Set<Object> duplicates) {
+        if (value instanceof ScriptObject && !(value instanceof ScriptFunction)) {
+            final ScriptObject object = (ScriptObject)value;
+            return new DebuggerValueDesc(name, !object.isEmpty(), value, objectAsString(object, all, duplicates));
+        } else {
+            return new DebuggerValueDesc(name, false, value, valueAsString(value));
+        }
+    }
+
+    /**
+     * Generate the descriptions for an object's properties.
+     * @param object     Object to introspect.
+     * @param all        true if to include non-enumerable values.
+     * @param duplicates Duplication set to avoid cycles.
+     * @return An array of DebuggerValueDesc.
+     */
+    private static DebuggerValueDesc[] getDebuggerValueDescs(final ScriptObject object, final boolean all, final Set<Object> duplicates) {
+        if (duplicates.contains(object)) {
+            return null;
+        }
+
+        duplicates.add(object);
+
+        final String[] keys = object.getOwnKeys(all);
+        final DebuggerValueDesc[] descs = new DebuggerValueDesc[keys.length];
+
+        for (int i = 0; i < keys.length; i++) {
+            final String key = keys[i];
+            descs[i] = valueInfo(key, object.get(key), true, duplicates);
+        }
+
+        duplicates.remove(object);
+
+        return descs;
+    }
+
+    /**
+     * Generate a string representation of a Script object.
+     * @param object     Script object to represent.
+     * @param all        true if to include non-enumerable values.
+     * @param duplicates Duplication set to avoid cycles.
+     * @return String representation.
+     */
+    private static String objectAsString(final ScriptObject object, final boolean all, final Set<Object> duplicates) {
+        final StringBuilder sb = new StringBuilder();
+
+        if (ScriptObject.isArray(object)) {
+            sb.append('[');
+            final long length = object.getLong("length");
+
+            for (long i = 0; i < length; i++) {
+                if (object.has(i)) {
+                    final Object valueAsObject = object.get(i);
+                    final boolean isUndefined = JSType.of(valueAsObject) == JSType.UNDEFINED;
+
+                    if (isUndefined) {
+                        if (i != 0) {
+                            sb.append(",");
+                        }
+                    } else {
+                        if (i != 0) {
+                            sb.append(", ");
+                        }
+
+                        if (valueAsObject instanceof ScriptObject && !(valueAsObject instanceof ScriptFunction)) {
+                            final String objectString = objectAsString((ScriptObject)valueAsObject, true, duplicates);
+                            sb.append(objectString != null ? objectString : "{...}");
+                        } else {
+                            sb.append(valueAsString(valueAsObject));
+                        }
+                    }
+                } else {
+                    if (i != 0) {
+                        sb.append(',');
+                    }
+                }
+            }
+
+            sb.append(']');
+        } else {
+            sb.append('{');
+            final DebuggerValueDesc[] descs = getDebuggerValueDescs(object, all, duplicates);
+
+            if (descs != null) {
+                for (int i = 0; i < descs.length; i++) {
+                    if (i != 0) {
+                        sb.append(", ");
+                    }
+
+                    final String valueAsString = descs[i].valueAsString;
+                    sb.append(descs[i].key);
+                    sb.append(": ");
+                    sb.append(descs[i].valueAsString);
+                }
+            }
+
+            sb.append('}');
+        }
+
+        return sb.toString();
+    }
+
+    /**
+     * This method returns a string representation of a value.
+     * @param value Arbitrary value to be displayed by the debugger.
+     * @return A string representation of the value or an array of DebuggerValueDesc.
+     */
+    private static String valueAsString(final Object value) {
+        final JSType type = JSType.of(value);
+
+        switch (type) {
+        case BOOLEAN:
+            return value.toString();
+
+        case STRING:
+            return escape((String)value);
+
+        case NUMBER:
+            return JSType.toString(((Number)value).doubleValue());
+
+        case NULL:
+            return "null";
+
+        case UNDEFINED:
+            return "undefined";
+
+        case OBJECT:
+            return ScriptRuntime.safeToString(value);
+
+        case FUNCTION:
+            if (value instanceof ScriptFunction) {
+                return ((ScriptFunction)value).toSource();
+            } else {
+                return value.toString();
+            }
+
+        default:
+            return value.toString();
+        }
+    }
+
+    /**
+     * Escape a string into a form that can be parsed by JavaScript.
+     * @param value String to be escaped.
+     * @return Escaped string.
+     */
+    private static String escape(final String value) {
+        final StringBuilder sb = new StringBuilder();
+
+        sb.append("\"");
+
+        for (final char ch : value.toCharArray()) {
+            switch (ch) {
+            case '\\':
+                sb.append("\\\\");
+                break;
+            case '"':
+                sb.append("\\\"");
+                break;
+            case '\'':
+                sb.append("\\\'");
+                break;
+            case '\b':
+                sb.append("\\b");
+                break;
+            case '\f':
+                sb.append("\\f");
+                break;
+            case '\n':
+                sb.append("\\n");
+                break;
+            case '\r':
+                sb.append("\\r");
+                break;
+            case '\t':
+                sb.append("\\t");
+                break;
+            default:
+                if (ch < ' ' || ch >= 0xFF) {
+                    sb.append("\\u");
+
+                    final String hex = Integer.toHexString(ch);
+                    for (int i = hex.length(); i < 4; i++) {
+                        sb.append('0');
+                    }
+                    sb.append(hex);
+                } else {
+                    sb.append(ch);
+                }
+
+                break;
+            }
+        }
+
+        sb.append("\"");
+
+        return sb.toString();
+    }
+}
+
+