--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.truffle.tools.debug.shell/src/com/oracle/truffle/tools/debug/shell/REPLMessage.java	Tue May 26 16:38:13 2015 -0700
@@ -0,0 +1,172 @@
+/*
+ * Copyright (c) 2015, 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.oracle.truffle.tools.debug.shell;
+
+import java.io.*;
+import java.util.*;
+import java.util.Map.Entry;
+
+/**
+ * A message for communication between a Read-Eval-Print-Loop server associated with a language
+ * implementation and a possibly remote client.
+ *
+ * @see REPLClient
+ * @see REPLServer
+ */
+public final class REPLMessage {
+
+    // Some standard keys and values
+    public static final String AST = "ast";
+    public static final String AST_DEPTH = "show-max-depth";
+    public static final String BACKTRACE = "backtrace";
+    public static final String BREAK_AT_LINE = "break-at-line";
+    public static final String BREAK_AT_LINE_ONCE = "break-at-line-once";
+    public static final String BREAK_AT_THROW = "break-at-throw";
+    public static final String BREAK_AT_THROW_ONCE = "break-at-throw-once";
+    public static final String BREAKPOINT_CONDITION = "breakpoint-condition";
+    public static final String BREAKPOINT_GROUP_ID = "breakpoint-group-id";
+    public static final String BREAKPOINT_HIT_COUNT = "breakpoint-hit-count";
+    public static final String BREAKPOINT_ID = "breakpoint-id";
+    public static final String BREAKPOINT_IGNORE_COUNT = "breakpoint-ignore-count";
+    public static final String BREAKPOINT_INFO = "breakpoint-info";
+    public static final String BREAKPOINT_STATE = "breakpoint-state";
+    public static final String CLEAR_BREAK = "clear-breakpoint";
+    public static final String CODE = "code";
+    public static final String CONTINUE = "continue";
+    public static final String DEBUG_LEVEL = "debug-level";
+    public static final String DELETE_BREAK = "delete-breakpoint";
+    public static final String DISABLE_BREAK = "disable-breakpoint";
+    public static final String DISPLAY_MSG = "displayable-message";
+    public static final String DOWN = "down";
+    public static final String ENABLE_BREAK = "enable-breakpoint";
+    public static final String EVAL = "eval";
+    public static final String FAILED = "failed";
+    public static final String FILE = "file";
+    public static final String FILE_PATH = "path";
+    public static final String FRAME = "frame";
+    public static final String FRAME_INFO = "frame-info";
+    public static final String FRAME_NUMBER = "frame-number";
+    public static final String INFO = "info";
+    public static final String INFO_KEY = "info-key";
+    public static final String INFO_VALUE = "info-value";
+    public static final String KILL = "kill";
+    public static final String LANGUAGE = "language";
+    public static final String LINE_NUMBER = "line-number";
+    public static final String LIST = "list";
+    public static final String LOAD_RUN = "load-run-source";
+    public static final String LOAD_STEP = "load-step-into-source";
+    public static final String METHOD_NAME = "method-name";
+    public static final String OP = "op";
+    public static final String OPTION = "option";
+    public static final String QUIT = "quit";
+    public static final String REPEAT = "repeat";
+    public static final String SET = "set";
+    public static final String SET_BREAK_CONDITION = "set-breakpoint-condition";
+    public static final String SOURCE_LINE_TEXT = "source-line-text";
+    public static final String SOURCE_LOCATION = "source-location";
+    public static final String SOURCE_NAME = "source-name";
+    public static final String SOURCE_TEXT = "source-text";
+    public static final String STACK_SIZE = "stack-size";
+    public static final String STATUS = "status";
+    public static final String STEP_INTO = "step-into";
+    public static final String STEP_OUT = "step-out";
+    public static final String STEP_OVER = "step-over";
+    public static final String STOPPED = "stopped";
+    public static final String SUB = "sub";
+    public static final String SUBTREE = "subtree";
+    public static final String SUCCEEDED = "succeeded";
+    public static final String TOPIC = "topic";
+    public static final String TRUFFLE = "truffle";
+    public static final String TRUFFLE_AST = "truffle-ast";
+    public static final String TRUFFLE_NODE = "truffle-node";
+    public static final String TRUFFLE_SUBTREE = "truffle-subtree";
+    public static final String UNSET_BREAK_CONDITION = "unset-breakpoint-condition";
+    public static final String UP = "up";
+    public static final String VALUE = "value";
+    public static final String WARNINGS = "warnings";
+    private final Map<String, String> map;
+
+    /**
+     * Creates an empty REPL message.
+     */
+    public REPLMessage() {
+        this.map = new TreeMap<>();
+    }
+
+    /**
+     * Creates a REPL message with an initial entry.
+     */
+    public REPLMessage(String key, String value) {
+        this();
+        map.put(key, value);
+    }
+
+    public REPLMessage(REPLMessage message) {
+        this.map = new TreeMap<>(message.map);
+    }
+
+    public String get(String key) {
+        return map.get(key);
+    }
+
+    /**
+     * Returns the specified key value as an integer; {@code null} if missing or non-numeric.
+     */
+    public Integer getIntValue(String key) {
+        final String value = map.get(key);
+        if (value != null) {
+            try {
+                return Integer.parseInt(value);
+            } catch (NumberFormatException e) {
+
+            }
+        }
+        return null;
+    }
+
+    public String put(String key, String value) {
+        return map.put(key, value);
+    }
+
+    public String remove(String key) {
+        return map.remove(key);
+    }
+
+    public Set<String> keys() {
+        return map.keySet();
+    }
+
+    public void print(PrintStream out, String linePrefix) {
+        map.keySet();
+
+        for (Entry<String, String> entry : map.entrySet()) {
+            String value = entry.getValue();
+            if (value != null && value.length() > 50) {
+                value = value.substring(0, 50) + " ...";
+            }
+            out.println(linePrefix + entry.getKey() + " = \"" + value + "\"");
+        }
+    }
+}