--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/truffle/com.oracle.truffle.tools.debug.shell/src/com/oracle/truffle/tools/debug/shell/client/REPLClientContext.java	Wed Jun 17 10:58:08 2015 +0200
@@ -0,0 +1,100 @@
+/*
+ * 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.client;
+
+import java.util.*;
+
+import com.oracle.truffle.api.source.*;
+import com.oracle.truffle.tools.debug.shell.*;
+
+/**
+ * Client context for interaction with a program halted by the {@link REPLServer}.
+ */
+public interface REPLClientContext {
+
+    /**
+     * The source code halted in this context.
+     */
+    Source source();
+
+    /**
+     * The 1-based line at which execution is halted in this context; 0 means unknown.
+     */
+    int lineNumber();
+
+    /**
+     * The Truffle stack where execution is halted in this context.
+     */
+    List<REPLFrame> frames();
+
+    /**
+     * The nesting level of the execution context: 0 means evaluating shell commands outside any
+     * executing program.
+     */
+    int level();
+
+    /**
+     * The source currently selected by the user; defaults to where halted.
+     */
+    Source getSelectedSource();
+
+    /**
+     * The frame number in this execution context currently selected by the user; defaults to 0.
+     */
+    int getSelectedFrameNumber();
+
+    /**
+     * Issue a command to the REPLServer that
+     * <ul>
+     * <li>can be specified by a single "op",</li>
+     * <li>produces information in the form of a single string, and</li>
+     * <li>has no effect on the execution state.</li>
+     * </ul>
+     */
+    String stringQuery(String op);
+
+    /**
+     * Sets a new "default" frame number for frame-related commands.
+     */
+    void selectFrameNumber(int frameNumber);
+
+    /**
+     * Sends an information message.
+     */
+    void displayInfo(String message);
+
+    void displayStack();
+
+    /**
+     * Send a message related to handling a command in this context.
+     */
+    void displayReply(String message);
+
+    /**
+     * Send a message related to failure while handling a command in this context.
+     */
+    void displayFailReply(String message);
+
+}