diff --git a/src/debug-debugger.js b/src/debug-debugger.js
new file mode 100644
index 0000000..14d8c88
--- /dev/null
+++ b/src/debug-debugger.js
@@ -0,0 +1,2073 @@
+// Copyright 2006-2008 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// Default number of frames to include in the response to backtrace request.
+const kDefaultBacktraceLength = 10;
+
+const Debug = {};
+
+// Regular expression to skip "crud" at the beginning of a source line which is
+// not really code. Currently the regular expression matches whitespace and
+// comments.
+const sourceLineBeginningSkip = /^(?:\s*(?:\/\*.*?\*\/)*)*/;
+
+// Debug events which can occour in the V8 JavaScript engine. These originate
+// from the API include file debug.h.
+Debug.DebugEvent = { Break: 1,
+                     Exception: 2,
+                     NewFunction: 3,
+                     BeforeCompile: 4,
+                     AfterCompile: 5,
+                     ScriptCollected: 6 };
+
+// Types of exceptions that can be broken upon.
+Debug.ExceptionBreak = { All : 0,
+                         Uncaught: 1 };
+
+// The different types of steps.
+Debug.StepAction = { StepOut: 0,
+                     StepNext: 1,
+                     StepIn: 2,
+                     StepMin: 3,
+                     StepInMin: 4 };
+
+// The different types of scripts matching enum ScriptType in objects.h.
+Debug.ScriptType = { Native: 0,
+                     Extension: 1,
+                     Normal: 2 };
+
+// The different types of script compilations matching enum
+// Script::CompilationType in objects.h.
+Debug.ScriptCompilationType = { Host: 0,
+                                Eval: 1,
+                                JSON: 2 };
+
+// The different script break point types.
+Debug.ScriptBreakPointType = { ScriptId: 0,
+                               ScriptName: 1 };
+
+function ScriptTypeFlag(type) {
+  return (1 << type);
+}
+
+// Globals.
+var next_response_seq = 0;
+var next_break_point_number = 1;
+var break_points = [];
+var script_break_points = [];
+
+
+// Create a new break point object and add it to the list of break points.
+function MakeBreakPoint(source_position, opt_line, opt_column, opt_script_break_point) {
+  var break_point = new BreakPoint(source_position, opt_line, opt_column, opt_script_break_point);
+  break_points.push(break_point);
+  return break_point;
+}
+
+
+// Object representing a break point.
+// NOTE: This object does not have a reference to the function having break
+// point as this would cause function not to be garbage collected when it is
+// not used any more. We do not want break points to keep functions alive.
+function BreakPoint(source_position, opt_line, opt_column, opt_script_break_point) {
+  this.source_position_ = source_position;
+  this.source_line_ = opt_line;
+  this.source_column_ = opt_column;
+  if (opt_script_break_point) {
+    this.script_break_point_ = opt_script_break_point;
+  } else {
+    this.number_ = next_break_point_number++;
+  }
+  this.hit_count_ = 0;
+  this.active_ = true;
+  this.condition_ = null;
+  this.ignoreCount_ = 0;
+}
+
+
+BreakPoint.prototype.number = function() {
+  return this.number_;
+};
+
+
+BreakPoint.prototype.func = function() {
+  return this.func_;
+};
+
+
+BreakPoint.prototype.source_position = function() {
+  return this.source_position_;
+};
+
+
+BreakPoint.prototype.hit_count = function() {
+  return this.hit_count_;
+};
+
+
+BreakPoint.prototype.active = function() {
+  if (this.script_break_point()) {
+    return this.script_break_point().active();
+  }
+  return this.active_;
+};
+
+
+BreakPoint.prototype.condition = function() {
+  if (this.script_break_point() && this.script_break_point().condition()) {
+    return this.script_break_point().condition();
+  }
+  return this.condition_;
+};
+
+
+BreakPoint.prototype.ignoreCount = function() {
+  return this.ignoreCount_;
+};
+
+
+BreakPoint.prototype.script_break_point = function() {
+  return this.script_break_point_;
+};
+
+
+BreakPoint.prototype.enable = function() {
+  this.active_ = true;
+};
+
+
+BreakPoint.prototype.disable = function() {
+  this.active_ = false;
+};
+
+
+BreakPoint.prototype.setCondition = function(condition) {
+  this.condition_ = condition;
+};
+
+
+BreakPoint.prototype.setIgnoreCount = function(ignoreCount) {
+  this.ignoreCount_ = ignoreCount;
+};
+
+
+BreakPoint.prototype.isTriggered = function(exec_state) {
+  // Break point not active - not triggered.
+  if (!this.active()) return false;
+
+  // Check for conditional break point.
+  if (this.condition()) {
+    // If break point has condition try to evaluate it in the top frame.
+    try {
+      var mirror = exec_state.frame(0).evaluate(this.condition());
+      // If no sensible mirror or non true value break point not triggered.
+      if (!(mirror instanceof ValueMirror) || !%ToBoolean(mirror.value_)) {
+        return false;
+      }
+    } catch (e) {
+      // Exception evaluating condition counts as not triggered.
+      return false;
+    }
+  }
+
+  // Update the hit count.
+  this.hit_count_++;
+  if (this.script_break_point_) {
+    this.script_break_point_.hit_count_++;
+  }
+
+  // If the break point has an ignore count it is not triggered.
+  if (this.ignoreCount_ > 0) {
+    this.ignoreCount_--;
+    return false;
+  }
+
+  // Break point triggered.
+  return true;
+};
+
+
+// Function called from the runtime when a break point is hit. Returns true if
+// the break point is triggered and supposed to break execution.
+function IsBreakPointTriggered(break_id, break_point) {
+  return break_point.isTriggered(MakeExecutionState(break_id));
+}
+
+
+// Object representing a script break point. The script is referenced by its
+// script name or script id and the break point is represented as line and
+// column.
+function ScriptBreakPoint(type, script_id_or_name, opt_line, opt_column,
+                          opt_groupId) {
+  this.type_ = type;
+  if (type == Debug.ScriptBreakPointType.ScriptId) {
+    this.script_id_ = script_id_or_name;
+  } else {  // type == Debug.ScriptBreakPointType.ScriptName
+    this.script_name_ = script_id_or_name;
+  }
+  this.line_ = opt_line || 0;
+  this.column_ = opt_column;
+  this.groupId_ = opt_groupId;
+  this.hit_count_ = 0;
+  this.active_ = true;
+  this.condition_ = null;
+  this.ignoreCount_ = 0;
+}
+
+
+ScriptBreakPoint.prototype.number = function() {
+  return this.number_;
+};
+
+
+ScriptBreakPoint.prototype.groupId = function() {
+  return this.groupId_;
+};
+
+
+ScriptBreakPoint.prototype.type = function() {
+  return this.type_;
+};
+
+
+ScriptBreakPoint.prototype.script_id = function() {
+  return this.script_id_;
+};
+
+
+ScriptBreakPoint.prototype.script_name = function() {
+  return this.script_name_;
+};
+
+
+ScriptBreakPoint.prototype.line = function() {
+  return this.line_;
+};
+
+
+ScriptBreakPoint.prototype.column = function() {
+  return this.column_;
+};
+
+
+ScriptBreakPoint.prototype.hit_count = function() {
+  return this.hit_count_;
+};
+
+
+ScriptBreakPoint.prototype.active = function() {
+  return this.active_;
+};
+
+
+ScriptBreakPoint.prototype.condition = function() {
+  return this.condition_;
+};
+
+
+ScriptBreakPoint.prototype.ignoreCount = function() {
+  return this.ignoreCount_;
+};
+
+
+ScriptBreakPoint.prototype.enable = function() {
+  this.active_ = true;
+};
+
+
+ScriptBreakPoint.prototype.disable = function() {
+  this.active_ = false;
+};
+
+
+ScriptBreakPoint.prototype.setCondition = function(condition) {
+  this.condition_ = condition;
+};
+
+
+ScriptBreakPoint.prototype.setIgnoreCount = function(ignoreCount) {
+  this.ignoreCount_ = ignoreCount;
+
+  // Set ignore count on all break points created from this script break point.
+  for (var i = 0; i < break_points.length; i++) {
+    if (break_points[i].script_break_point() === this) {
+      break_points[i].setIgnoreCount(ignoreCount);
+    }
+  }
+};
+
+
+// Check whether a script matches this script break point. Currently this is
+// only based on script name.
+ScriptBreakPoint.prototype.matchesScript = function(script) {
+  if (this.type_ == Debug.ScriptBreakPointType.ScriptId) {
+    return this.script_id_ == script.id;
+  } else {  // this.type_ == Debug.ScriptBreakPointType.ScriptName
+    return this.script_name_ == script.name &&
+           script.line_offset <= this.line_  &&
+           this.line_ < script.line_offset + script.lineCount();
+  }
+};
+
+
+// Set the script break point in a script.
+ScriptBreakPoint.prototype.set = function (script) {
+  var column = this.column();
+  var line = this.line();
+  // If the column is undefined the break is on the line. To help locate the
+  // first piece of breakable code on the line try to find the column on the
+  // line which contains some source.
+  if (IS_UNDEFINED(column)) {
+    var source_line = script.sourceLine(this.line());
+
+    // Allocate array for caching the columns where the actual source starts.
+    if (!script.sourceColumnStart_) {
+      script.sourceColumnStart_ = new Array(script.lineCount());
+    }
+
+    // Fill cache if needed and get column where the actual source starts.
+    if (IS_UNDEFINED(script.sourceColumnStart_[line])) {
+      script.sourceColumnStart_[line] =
+          source_line.match(sourceLineBeginningSkip)[0].length;
+    }
+    column = script.sourceColumnStart_[line];
+  }
+
+  // Convert the line and column into an absolute position within the script.
+  var pos = Debug.findScriptSourcePosition(script, this.line(), column);
+
+  // If the position is not found in the script (the script might be shorter
+  // than it used to be) just ignore it.
+  if (pos === null) return;
+
+  // Create a break point object and set the break point.
+  break_point = MakeBreakPoint(pos, this.line(), this.column(), this);
+  break_point.setIgnoreCount(this.ignoreCount());
+  %SetScriptBreakPoint(script, pos, break_point);
+
+  return break_point;
+};
+
+
+// Clear all the break points created from this script break point
+ScriptBreakPoint.prototype.clear = function () {
+  var remaining_break_points = [];
+  for (var i = 0; i < break_points.length; i++) {
+    if (break_points[i].script_break_point() &&
+        break_points[i].script_break_point() === this) {
+      %ClearBreakPoint(break_points[i]);
+    } else {
+      remaining_break_points.push(break_points[i]);
+    }
+  }
+  break_points = remaining_break_points;
+};
+
+
+// Function called from runtime when a new script is compiled to set any script
+// break points set in this script.
+function UpdateScriptBreakPoints(script) {
+  for (var i = 0; i < script_break_points.length; i++) {
+    if (script_break_points[i].type() == Debug.ScriptBreakPointType.ScriptName &&
+        script_break_points[i].matchesScript(script)) {
+      script_break_points[i].set(script);
+    }
+  }
+}
+
+
+Debug.setListener = function(listener, opt_data) {
+  if (!IS_FUNCTION(listener) && !IS_UNDEFINED(listener) && !IS_NULL(listener)) {
+    throw new Error('Parameters have wrong types.');
+  }
+  %SetDebugEventListener(listener, opt_data);
+};
+
+
+Debug.breakExecution = function(f) {
+  %Break();
+};
+
+Debug.breakLocations = function(f) {
+  if (!IS_FUNCTION(f)) throw new Error('Parameters have wrong types.');
+  return %GetBreakLocations(f);
+};
+
+// Returns a Script object. If the parameter is a function the return value
+// is the script in which the function is defined. If the parameter is a string
+// the return value is the script for which the script name has that string
+// value.  If it is a regexp and there is a unique script whose name matches
+// we return that, otherwise undefined.
+Debug.findScript = function(func_or_script_name) {
+  if (IS_FUNCTION(func_or_script_name)) {
+    return %FunctionGetScript(func_or_script_name);
+  } else if (IS_REGEXP(func_or_script_name)) {
+    var scripts = Debug.scripts();
+    var last_result = null;
+    var result_count = 0;
+    for (var i in scripts) {
+      var script = scripts[i];
+      if (func_or_script_name.test(script.name)) {
+        last_result = script;
+        result_count++;
+      }
+    }
+    // Return the unique script matching the regexp.  If there are more
+    // than one we don't return a value since there is no good way to
+    // decide which one to return.  Returning a "random" one, say the
+    // first, would introduce nondeterminism (or something close to it)
+    // because the order is the heap iteration order.
+    if (result_count == 1) {
+      return last_result;
+    } else {
+      return undefined;
+    }
+  } else {
+    return %GetScript(func_or_script_name);
+  }
+};
+
+// Returns the script source. If the parameter is a function the return value
+// is the script source for the script in which the function is defined. If the
+// parameter is a string the return value is the script for which the script
+// name has that string value.
+Debug.scriptSource = function(func_or_script_name) {
+  return this.findScript(func_or_script_name).source;
+};
+
+Debug.source = function(f) {
+  if (!IS_FUNCTION(f)) throw new Error('Parameters have wrong types.');
+  return %FunctionGetSourceCode(f);
+};
+
+Debug.disassemble = function(f) {
+  if (!IS_FUNCTION(f)) throw new Error('Parameters have wrong types.');
+  return %DebugDisassembleFunction(f);
+};
+
+Debug.disassembleConstructor = function(f) {
+  if (!IS_FUNCTION(f)) throw new Error('Parameters have wrong types.');
+  return %DebugDisassembleConstructor(f);
+};
+
+Debug.sourcePosition = function(f) {
+  if (!IS_FUNCTION(f)) throw new Error('Parameters have wrong types.');
+  return %FunctionGetScriptSourcePosition(f);
+};
+
+
+Debug.findFunctionSourceLocation = function(func, opt_line, opt_column) {
+  var script = %FunctionGetScript(func);
+  var script_offset = %FunctionGetScriptSourcePosition(func);
+  return script.locationFromLine(opt_line, opt_column, script_offset);
+}
+
+
+// Returns the character position in a script based on a line number and an
+// optional position within that line.
+Debug.findScriptSourcePosition = function(script, opt_line, opt_column) {
+  var location = script.locationFromLine(opt_line, opt_column);
+  return location ? location.position : null;
+}
+
+
+Debug.findBreakPoint = function(break_point_number, remove) {
+  var break_point;
+  for (var i = 0; i < break_points.length; i++) {
+    if (break_points[i].number() == break_point_number) {
+      break_point = break_points[i];
+      // Remove the break point from the list if requested.
+      if (remove) {
+        break_points.splice(i, 1);
+      }
+      break;
+    }
+  }
+  if (break_point) {
+    return break_point;
+  } else {
+    return this.findScriptBreakPoint(break_point_number, remove);
+  }
+};
+
+
+Debug.setBreakPoint = function(func, opt_line, opt_column, opt_condition) {
+  if (!IS_FUNCTION(func)) throw new Error('Parameters have wrong types.');
+  // Break points in API functions are not supported.
+  if (%FunctionIsAPIFunction(func)) {
+    throw new Error('Cannot set break point in native code.');
+  }
+  // Find source position relative to start of the function
+  var break_position =
+      this.findFunctionSourceLocation(func, opt_line, opt_column).position;
+  var source_position = break_position - this.sourcePosition(func);
+  // Find the script for the function.
+  var script = %FunctionGetScript(func);
+  // Break in builtin JavaScript code is not supported.
+  if (script.type == Debug.ScriptType.Native) {
+    throw new Error('Cannot set break point in native code.');
+  }
+  // If the script for the function has a name convert this to a script break
+  // point.
+  if (script && script.id) {
+    // Adjust the source position to be script relative.
+    source_position += %FunctionGetScriptSourcePosition(func);
+    // Find line and column for the position in the script and set a script
+    // break point from that.
+    var location = script.locationFromPosition(source_position, false);
+    return this.setScriptBreakPointById(script.id,
+                                        location.line, location.column,
+                                        opt_condition);
+  } else {
+    // Set a break point directly on the function.
+    var break_point = MakeBreakPoint(source_position, opt_line, opt_column);
+    %SetFunctionBreakPoint(func, source_position, break_point);
+    break_point.setCondition(opt_condition);
+    return break_point.number();
+  }
+};
+
+
+Debug.enableBreakPoint = function(break_point_number) {
+  var break_point = this.findBreakPoint(break_point_number, false);
+  break_point.enable();
+};
+
+
+Debug.disableBreakPoint = function(break_point_number) {
+  var break_point = this.findBreakPoint(break_point_number, false);
+  break_point.disable();
+};
+
+
+Debug.changeBreakPointCondition = function(break_point_number, condition) {
+  var break_point = this.findBreakPoint(break_point_number, false);
+  break_point.setCondition(condition);
+};
+
+
+Debug.changeBreakPointIgnoreCount = function(break_point_number, ignoreCount) {
+  if (ignoreCount < 0) {
+    throw new Error('Invalid argument');
+  }
+  var break_point = this.findBreakPoint(break_point_number, false);
+  break_point.setIgnoreCount(ignoreCount);
+};
+
+
+Debug.clearBreakPoint = function(break_point_number) {
+  var break_point = this.findBreakPoint(break_point_number, true);
+  if (break_point) {
+    return %ClearBreakPoint(break_point);
+  } else {
+    break_point = this.findScriptBreakPoint(break_point_number, true);
+    if (!break_point) {
+      throw new Error('Invalid breakpoint');
+    }
+  }
+};
+
+
+Debug.clearAllBreakPoints = function() {
+  for (var i = 0; i < break_points.length; i++) {
+    break_point = break_points[i];
+    %ClearBreakPoint(break_point);
+  }
+  break_points = [];
+};
+
+
+Debug.findScriptBreakPoint = function(break_point_number, remove) {
+  var script_break_point;
+  for (var i = 0; i < script_break_points.length; i++) {
+    if (script_break_points[i].number() == break_point_number) {
+      script_break_point = script_break_points[i];
+      // Remove the break point from the list if requested.
+      if (remove) {
+        script_break_point.clear();
+        script_break_points.splice(i,1);
+      }
+      break;
+    }
+  }
+  return script_break_point;
+}
+
+
+// Sets a breakpoint in a script identified through id or name at the
+// specified source line and column within that line.
+Debug.setScriptBreakPoint = function(type, script_id_or_name,
+                                     opt_line, opt_column, opt_condition,
+                                     opt_groupId) {
+  // Create script break point object.
+  var script_break_point =
+      new ScriptBreakPoint(type, script_id_or_name, opt_line, opt_column,
+                           opt_groupId);
+
+  // Assign number to the new script break point and add it.
+  script_break_point.number_ = next_break_point_number++;
+  script_break_point.setCondition(opt_condition);
+  script_break_points.push(script_break_point);
+
+  // Run through all scripts to see if this script break point matches any
+  // loaded scripts.
+  var scripts = this.scripts();
+  for (var i = 0; i < scripts.length; i++) {
+    if (script_break_point.matchesScript(scripts[i])) {
+      script_break_point.set(scripts[i]);
+    }
+  }
+
+  return script_break_point.number();
+}
+
+
+Debug.setScriptBreakPointById = function(script_id,
+                                         opt_line, opt_column,
+                                         opt_condition, opt_groupId) {
+  return this.setScriptBreakPoint(Debug.ScriptBreakPointType.ScriptId,
+                                  script_id, opt_line, opt_column,
+                                  opt_condition, opt_groupId);
+}
+
+
+Debug.setScriptBreakPointByName = function(script_name,
+                                           opt_line, opt_column,
+                                           opt_condition, opt_groupId) {
+  return this.setScriptBreakPoint(Debug.ScriptBreakPointType.ScriptName,
+                                  script_name, opt_line, opt_column,
+                                  opt_condition, opt_groupId);
+}
+
+
+Debug.enableScriptBreakPoint = function(break_point_number) {
+  var script_break_point = this.findScriptBreakPoint(break_point_number, false);
+  script_break_point.enable();
+};
+
+
+Debug.disableScriptBreakPoint = function(break_point_number) {
+  var script_break_point = this.findScriptBreakPoint(break_point_number, false);
+  script_break_point.disable();
+};
+
+
+Debug.changeScriptBreakPointCondition = function(break_point_number, condition) {
+  var script_break_point = this.findScriptBreakPoint(break_point_number, false);
+  script_break_point.setCondition(condition);
+};
+
+
+Debug.changeScriptBreakPointIgnoreCount = function(break_point_number, ignoreCount) {
+  if (ignoreCount < 0) {
+    throw new Error('Invalid argument');
+  }
+  var script_break_point = this.findScriptBreakPoint(break_point_number, false);
+  script_break_point.setIgnoreCount(ignoreCount);
+};
+
+
+Debug.scriptBreakPoints = function() {
+  return script_break_points;
+}
+
+
+Debug.clearStepping = function() {
+  %ClearStepping();
+}
+
+Debug.setBreakOnException = function() {
+  return %ChangeBreakOnException(Debug.ExceptionBreak.All, true);
+};
+
+Debug.clearBreakOnException = function() {
+  return %ChangeBreakOnException(Debug.ExceptionBreak.All, false);
+};
+
+Debug.setBreakOnUncaughtException = function() {
+  return %ChangeBreakOnException(Debug.ExceptionBreak.Uncaught, true);
+};
+
+Debug.clearBreakOnUncaughtException = function() {
+  return %ChangeBreakOnException(Debug.ExceptionBreak.Uncaught, false);
+};
+
+Debug.showBreakPoints = function(f, full) {
+  if (!IS_FUNCTION(f)) throw new Error('Parameters have wrong types.');
+  var source = full ? this.scriptSource(f) : this.source(f);
+  var offset = full ? this.sourcePosition(f) : 0;
+  var locations = this.breakLocations(f);
+  if (!locations) return source;
+  locations.sort(function(x, y) { return x - y; });
+  var result = "";
+  var prev_pos = 0;
+  var pos;
+  for (var i = 0; i < locations.length; i++) {
+    pos = locations[i] - offset;
+    result += source.slice(prev_pos, pos);
+    result += "[B" + i + "]";
+    prev_pos = pos;
+  }
+  pos = source.length;
+  result += source.substring(prev_pos, pos);
+  return result;
+};
+
+
+// Get all the scripts currently loaded. Locating all the scripts is based on
+// scanning the heap.
+Debug.scripts = function() {
+  // Collect all scripts in the heap.
+  return %DebugGetLoadedScripts();
+}
+
+function MakeExecutionState(break_id) {
+  return new ExecutionState(break_id);
+}
+
+function ExecutionState(break_id) {
+  this.break_id = break_id;
+  this.selected_frame = 0;
+}
+
+ExecutionState.prototype.prepareStep = function(opt_action, opt_count) {
+  var action = Debug.StepAction.StepIn;
+  if (!IS_UNDEFINED(opt_action)) action = %ToNumber(opt_action);
+  var count = opt_count ? %ToNumber(opt_count) : 1;
+
+  return %PrepareStep(this.break_id, action, count);
+}
+
+ExecutionState.prototype.evaluateGlobal = function(source, disable_break) {
+  return MakeMirror(
+      %DebugEvaluateGlobal(this.break_id, source, Boolean(disable_break)));
+};
+
+ExecutionState.prototype.frameCount = function() {
+  return %GetFrameCount(this.break_id);
+};
+
+ExecutionState.prototype.threadCount = function() {
+  return %GetThreadCount(this.break_id);
+};
+
+ExecutionState.prototype.frame = function(opt_index) {
+  // If no index supplied return the selected frame.
+  if (opt_index == null) opt_index = this.selected_frame;
+  return new FrameMirror(this.break_id, opt_index);
+};
+
+ExecutionState.prototype.cframesValue = function(opt_from_index, opt_to_index) {
+  return %GetCFrames(this.break_id);
+};
+
+ExecutionState.prototype.setSelectedFrame = function(index) {
+  var i = %ToNumber(index);
+  if (i < 0 || i >= this.frameCount()) throw new Error('Illegal frame index.');
+  this.selected_frame = i;
+};
+
+ExecutionState.prototype.selectedFrame = function() {
+  return this.selected_frame;
+};
+
+ExecutionState.prototype.debugCommandProcessor = function(opt_is_running) {
+  return new DebugCommandProcessor(this, opt_is_running);
+};
+
+
+function MakeBreakEvent(exec_state, break_points_hit) {
+  return new BreakEvent(exec_state, break_points_hit);
+}
+
+
+function BreakEvent(exec_state, break_points_hit) {
+  this.exec_state_ = exec_state;
+  this.break_points_hit_ = break_points_hit;
+}
+
+
+BreakEvent.prototype.executionState = function() {
+  return this.exec_state_;
+};
+
+
+BreakEvent.prototype.eventType = function() {
+  return Debug.DebugEvent.Break;
+};
+
+
+BreakEvent.prototype.func = function() {
+  return this.exec_state_.frame(0).func();
+};
+
+
+BreakEvent.prototype.sourceLine = function() {
+  return this.exec_state_.frame(0).sourceLine();
+};
+
+
+BreakEvent.prototype.sourceColumn = function() {
+  return this.exec_state_.frame(0).sourceColumn();
+};
+
+
+BreakEvent.prototype.sourceLineText = function() {
+  return this.exec_state_.frame(0).sourceLineText();
+};
+
+
+BreakEvent.prototype.breakPointsHit = function() {
+  return this.break_points_hit_;
+};
+
+
+BreakEvent.prototype.toJSONProtocol = function() {
+  var o = { seq: next_response_seq++,
+            type: "event",
+            event: "break",
+            body: { invocationText: this.exec_state_.frame(0).invocationText(),
+                  }
+          };
+
+  // Add script related information to the event if available.
+  var script = this.func().script();
+  if (script) {
+    o.body.sourceLine = this.sourceLine(),
+    o.body.sourceColumn = this.sourceColumn(),
+    o.body.sourceLineText = this.sourceLineText(),
+    o.body.script = MakeScriptObject_(script, false);
+  }
+
+  // Add an Array of break points hit if any.
+  if (this.breakPointsHit()) {
+    o.body.breakpoints = [];
+    for (var i = 0; i < this.breakPointsHit().length; i++) {
+      // Find the break point number. For break points originating from a
+      // script break point supply the script break point number.
+      var breakpoint = this.breakPointsHit()[i];
+      var script_break_point = breakpoint.script_break_point();
+      var number;
+      if (script_break_point) {
+        number = script_break_point.number();
+      } else {
+        number = breakpoint.number();
+      }
+      o.body.breakpoints.push(number);
+    }
+  }
+  return JSON.stringify(ObjectToProtocolObject_(o));
+};
+
+
+function MakeExceptionEvent(exec_state, exception, uncaught) {
+  return new ExceptionEvent(exec_state, exception, uncaught);
+}
+
+
+function ExceptionEvent(exec_state, exception, uncaught) {
+  this.exec_state_ = exec_state;
+  this.exception_ = exception;
+  this.uncaught_ = uncaught;
+}
+
+
+ExceptionEvent.prototype.executionState = function() {
+  return this.exec_state_;
+};
+
+
+ExceptionEvent.prototype.eventType = function() {
+  return Debug.DebugEvent.Exception;
+};
+
+
+ExceptionEvent.prototype.exception = function() {
+  return this.exception_;
+}
+
+
+ExceptionEvent.prototype.uncaught = function() {
+  return this.uncaught_;
+}
+
+
+ExceptionEvent.prototype.func = function() {
+  return this.exec_state_.frame(0).func();
+};
+
+
+ExceptionEvent.prototype.sourceLine = function() {
+  return this.exec_state_.frame(0).sourceLine();
+};
+
+
+ExceptionEvent.prototype.sourceColumn = function() {
+  return this.exec_state_.frame(0).sourceColumn();
+};
+
+
+ExceptionEvent.prototype.sourceLineText = function() {
+  return this.exec_state_.frame(0).sourceLineText();
+};
+
+
+ExceptionEvent.prototype.toJSONProtocol = function() {
+  var o = new ProtocolMessage();
+  o.event = "exception";
+  o.body = { uncaught: this.uncaught_,
+             exception: MakeMirror(this.exception_)
+           };
+
+  // Exceptions might happen whithout any JavaScript frames.
+  if (this.exec_state_.frameCount() > 0) {
+    o.body.sourceLine = this.sourceLine();
+    o.body.sourceColumn = this.sourceColumn();
+    o.body.sourceLineText = this.sourceLineText();
+
+    // Add script information to the event if available.
+    var script = this.func().script();
+    if (script) {
+      o.body.script = MakeScriptObject_(script, false);
+    }
+  } else {
+    o.body.sourceLine = -1;
+  }
+
+  return o.toJSONProtocol();
+};
+
+
+function MakeCompileEvent(exec_state, script, before) {
+  return new CompileEvent(exec_state, script, before);
+}
+
+
+function CompileEvent(exec_state, script, before) {
+  this.exec_state_ = exec_state;
+  this.script_ = MakeMirror(script);
+  this.before_ = before;
+}
+
+
+CompileEvent.prototype.executionState = function() {
+  return this.exec_state_;
+};
+
+
+CompileEvent.prototype.eventType = function() {
+  if (this.before_) {
+    return Debug.DebugEvent.BeforeCompile;
+  } else {
+    return Debug.DebugEvent.AfterCompile;
+  }
+};
+
+
+CompileEvent.prototype.script = function() {
+  return this.script_;
+};
+
+
+CompileEvent.prototype.toJSONProtocol = function() {
+  var o = new ProtocolMessage();
+  o.running = true;
+  if (this.before_) {
+    o.event = "beforeCompile";
+  } else {
+    o.event = "afterCompile";
+  }
+  o.body = {};
+  o.body.script = this.script_;
+
+  return o.toJSONProtocol();
+}
+
+
+function MakeNewFunctionEvent(func) {
+  return new NewFunctionEvent(func);
+}
+
+
+function NewFunctionEvent(func) {
+  this.func = func;
+}
+
+
+NewFunctionEvent.prototype.eventType = function() {
+  return Debug.DebugEvent.NewFunction;
+};
+
+
+NewFunctionEvent.prototype.name = function() {
+  return this.func.name;
+};
+
+
+NewFunctionEvent.prototype.setBreakPoint = function(p) {
+  Debug.setBreakPoint(this.func, p || 0);
+};
+
+
+function MakeScriptCollectedEvent(exec_state, id) {
+  return new ScriptCollectedEvent(exec_state, id);
+}
+
+
+function ScriptCollectedEvent(exec_state, id) {
+  this.exec_state_ = exec_state;
+  this.id_ = id;
+}
+
+
+ScriptCollectedEvent.prototype.id = function() {
+  return this.id_;
+};
+
+
+ScriptCollectedEvent.prototype.executionState = function() {
+  return this.exec_state_;
+};
+
+
+ScriptCollectedEvent.prototype.toJSONProtocol = function() {
+  var o = new ProtocolMessage();
+  o.running = true;
+  o.event = "scriptCollected";
+  o.body = {};
+  o.body.script = { id: this.id() };
+  return o.toJSONProtocol();
+}
+
+
+function MakeScriptObject_(script, include_source) {
+  var o = { id: script.id(),
+            name: script.name(),
+            lineOffset: script.lineOffset(),
+            columnOffset: script.columnOffset(),
+            lineCount: script.lineCount(),
+          };
+  if (!IS_UNDEFINED(script.data())) {
+    o.data = script.data();
+  }
+  if (include_source) {
+    o.source = script.source();
+  }
+  return o;
+};
+
+
+function DebugCommandProcessor(exec_state, opt_is_running) {
+  this.exec_state_ = exec_state;
+  this.running_ = opt_is_running || false;
+};
+
+
+DebugCommandProcessor.prototype.processDebugRequest = function (request) {
+  return this.processDebugJSONRequest(request);
+}
+
+
+function ProtocolMessage(request) {
+  // Update sequence number.
+  this.seq = next_response_seq++;
+
+  if (request) {
+    // If message is based on a request this is a response. Fill the initial
+    // response from the request.
+    this.type = 'response';
+    this.request_seq = request.seq;
+    this.command = request.command;
+  } else {
+    // If message is not based on a request it is a dabugger generated event.
+    this.type = 'event';
+  }
+  this.success = true;
+  // Handler may set this field to control debugger state.
+  this.running = undefined;
+}
+
+
+ProtocolMessage.prototype.setOption = function(name, value) {
+  if (!this.options_) {
+    this.options_ = {};
+  }
+  this.options_[name] = value;
+}
+
+
+ProtocolMessage.prototype.failed = function(message) {
+  this.success = false;
+  this.message = message;
+}
+
+
+ProtocolMessage.prototype.toJSONProtocol = function() {
+  // Encode the protocol header.
+  var json = {};
+  json.seq= this.seq;
+  if (this.request_seq) {
+    json.request_seq = this.request_seq;
+  }
+  json.type = this.type;
+  if (this.event) {
+    json.event = this.event;
+  }
+  if (this.command) {
+    json.command = this.command;
+  }
+  if (this.success) {
+    json.success = this.success;
+  } else {
+    json.success = false;
+  }
+  if (this.body) {
+    // Encode the body part.
+    var bodyJson;
+    var serializer = MakeMirrorSerializer(true, this.options_);
+    if (this.body instanceof Mirror) {
+      bodyJson = serializer.serializeValue(this.body);
+    } else if (this.body instanceof Array) {
+      bodyJson = [];
+      for (var i = 0; i < this.body.length; i++) {
+        if (this.body[i] instanceof Mirror) {
+          bodyJson.push(serializer.serializeValue(this.body[i]));
+        } else {
+          bodyJson.push(ObjectToProtocolObject_(this.body[i], serializer));
+        }
+      }
+    } else {
+      bodyJson = ObjectToProtocolObject_(this.body, serializer);
+    }
+    json.body = bodyJson;
+    json.refs = serializer.serializeReferencedObjects();
+  }
+  if (this.message) {
+    json.message = this.message;
+  }
+  json.running = this.running;
+  return JSON.stringify(json);
+}
+
+
+DebugCommandProcessor.prototype.createResponse = function(request) {
+  return new ProtocolMessage(request);
+};
+
+
+DebugCommandProcessor.prototype.processDebugJSONRequest = function(json_request) {
+  var request;  // Current request.
+  var response;  // Generated response.
+  try {
+    try {
+      // Convert the JSON string to an object.
+      request = %CompileString('(' + json_request + ')', false)();
+
+      // Create an initial response.
+      response = this.createResponse(request);
+
+      if (!request.type) {
+        throw new Error('Type not specified');
+      }
+
+      if (request.type != 'request') {
+        throw new Error("Illegal type '" + request.type + "' in request");
+      }
+
+      if (!request.command) {
+        throw new Error('Command not specified');
+      }
+
+      // TODO(yurys): remove request.arguments.compactFormat check once
+      // ChromeDevTools are switched to 'inlineRefs'
+      if (request.arguments && (request.arguments.inlineRefs ||
+                                request.arguments.compactFormat)) {
+        response.setOption('inlineRefs', true);
+      }
+
+      if (request.command == 'continue') {
+        this.continueRequest_(request, response);
+      } else if (request.command == 'break') {
+        this.breakRequest_(request, response);
+      } else if (request.command == 'setbreakpoint') {
+        this.setBreakPointRequest_(request, response);
+      } else if (request.command == 'changebreakpoint') {
+        this.changeBreakPointRequest_(request, response);
+      } else if (request.command == 'clearbreakpoint') {
+        this.clearBreakPointRequest_(request, response);
+      } else if (request.command == 'clearbreakpointgroup') {
+        this.clearBreakPointGroupRequest_(request, response);
+      } else if (request.command == 'backtrace') {
+        this.backtraceRequest_(request, response);
+      } else if (request.command == 'frame') {
+        this.frameRequest_(request, response);
+      } else if (request.command == 'scopes') {
+        this.scopesRequest_(request, response);
+      } else if (request.command == 'scope') {
+        this.scopeRequest_(request, response);
+      } else if (request.command == 'evaluate') {
+        this.evaluateRequest_(request, response);
+      } else if (request.command == 'lookup') {
+        this.lookupRequest_(request, response);
+      } else if (request.command == 'references') {
+        this.referencesRequest_(request, response);
+      } else if (request.command == 'source') {
+        this.sourceRequest_(request, response);
+      } else if (request.command == 'scripts') {
+        this.scriptsRequest_(request, response);
+      } else if (request.command == 'threads') {
+        this.threadsRequest_(request, response);
+      } else if (request.command == 'suspend') {
+        this.suspendRequest_(request, response);
+      } else if (request.command == 'version') {
+        this.versionRequest_(request, response);
+      } else if (request.command == 'profile') {
+        this.profileRequest_(request, response);
+      } else {
+        throw new Error('Unknown command "' + request.command + '" in request');
+      }
+    } catch (e) {
+      // If there is no response object created one (without command).
+      if (!response) {
+        response = this.createResponse();
+      }
+      response.success = false;
+      response.message = %ToString(e);
+    }
+
+    // Return the response as a JSON encoded string.
+    try {
+      if (!IS_UNDEFINED(response.running)) {
+        // Response controls running state.
+        this.running_ = response.running;
+      }
+      response.running = this.running_; 
+      return response.toJSONProtocol();
+    } catch (e) {
+      // Failed to generate response - return generic error.
+      return '{"seq":' + response.seq + ',' +
+              '"request_seq":' + request.seq + ',' +
+              '"type":"response",' +
+              '"success":false,' +
+              '"message":"Internal error: ' + %ToString(e) + '"}';
+    }
+  } catch (e) {
+    // Failed in one of the catch blocks above - most generic error.
+    return '{"seq":0,"type":"response","success":false,"message":"Internal error"}';
+  }
+};
+
+
+DebugCommandProcessor.prototype.continueRequest_ = function(request, response) {
+  // Check for arguments for continue.
+  if (request.arguments) {
+    var count = 1;
+    var action = Debug.StepAction.StepIn;
+
+    // Pull out arguments.
+    var stepaction = request.arguments.stepaction;
+    var stepcount = request.arguments.stepcount;
+
+    // Get the stepcount argument if any.
+    if (stepcount) {
+      count = %ToNumber(stepcount);
+      if (count < 0) {
+        throw new Error('Invalid stepcount argument "' + stepcount + '".');
+      }
+    }
+
+    // Get the stepaction argument.
+    if (stepaction) {
+      if (stepaction == 'in') {
+        action = Debug.StepAction.StepIn;
+      } else if (stepaction == 'min') {
+        action = Debug.StepAction.StepMin;
+      } else if (stepaction == 'next') {
+        action = Debug.StepAction.StepNext;
+      } else if (stepaction == 'out') {
+        action = Debug.StepAction.StepOut;
+      } else {
+        throw new Error('Invalid stepaction argument "' + stepaction + '".');
+      }
+    }
+
+    // Setup the VM for stepping.
+    this.exec_state_.prepareStep(action, count);
+  }
+
+  // VM should be running after executing this request.
+  response.running = true;
+};
+
+
+DebugCommandProcessor.prototype.breakRequest_ = function(request, response) {
+  // Ignore as break command does not do anything when broken.
+};
+
+
+DebugCommandProcessor.prototype.setBreakPointRequest_ =
+    function(request, response) {
+  // Check for legal request.
+  if (!request.arguments) {
+    response.failed('Missing arguments');
+    return;
+  }
+
+  // Pull out arguments.
+  var type = request.arguments.type;
+  var target = request.arguments.target;
+  var line = request.arguments.line;
+  var column = request.arguments.column;
+  var enabled = IS_UNDEFINED(request.arguments.enabled) ?
+      true : request.arguments.enabled;
+  var condition = request.arguments.condition;
+  var ignoreCount = request.arguments.ignoreCount;
+  var groupId = request.arguments.groupId;
+
+  // Check for legal arguments.
+  if (!type || IS_UNDEFINED(target)) {
+    response.failed('Missing argument "type" or "target"');
+    return;
+  }
+  if (type != 'function' && type != 'handle' &&
+      type != 'script' && type != 'scriptId') {
+    response.failed('Illegal type "' + type + '"');
+    return;
+  }
+
+  // Either function or script break point.
+  var break_point_number;
+  if (type == 'function') {
+    // Handle function break point.
+    if (!IS_STRING(target)) {
+      response.failed('Argument "target" is not a string value');
+      return;
+    }
+    var f;
+    try {
+      // Find the function through a global evaluate.
+      f = this.exec_state_.evaluateGlobal(target).value();
+    } catch (e) {
+      response.failed('Error: "' + %ToString(e) +
+                      '" evaluating "' + target + '"');
+      return;
+    }
+    if (!IS_FUNCTION(f)) {
+      response.failed('"' + target + '" does not evaluate to a function');
+      return;
+    }
+
+    // Set function break point.
+    break_point_number = Debug.setBreakPoint(f, line, column, condition);
+  } else if (type == 'handle') {
+    // Find the object pointed by the specified handle.
+    var handle = parseInt(target, 10);
+    var mirror = LookupMirror(handle);
+    if (!mirror) {
+      return response.failed('Object #' + handle + '# not found');
+    }
+    if (!mirror.isFunction()) {
+      return response.failed('Object #' + handle + '# is not a function');
+    }
+
+    // Set function break point.
+    break_point_number = Debug.setBreakPoint(mirror.value(),
+                                             line, column, condition);
+  } else if (type == 'script') {
+    // set script break point.
+    break_point_number =
+        Debug.setScriptBreakPointByName(target, line, column, condition,
+                                        groupId);
+  } else {  // type == 'scriptId.
+    break_point_number =
+        Debug.setScriptBreakPointById(target, line, column, condition, groupId);
+  }
+
+  // Set additional break point properties.
+  var break_point = Debug.findBreakPoint(break_point_number);
+  if (ignoreCount) {
+    Debug.changeBreakPointIgnoreCount(break_point_number, ignoreCount);
+  }
+  if (!enabled) {
+    Debug.disableBreakPoint(break_point_number);
+  }
+
+  // Add the break point number to the response.
+  response.body = { type: type,
+                    breakpoint: break_point_number }
+
+  // Add break point information to the response.
+  if (break_point instanceof ScriptBreakPoint) {
+    if (break_point.type() == Debug.ScriptBreakPointType.ScriptId) {
+      response.body.type = 'scriptId';
+      response.body.script_id = break_point.script_id();
+    } else {
+      response.body.type = 'scriptName';
+      response.body.script_name = break_point.script_name();
+    }
+    response.body.line = break_point.line();
+    response.body.column = break_point.column();
+  } else {
+    response.body.type = 'function';
+  }
+};
+
+
+DebugCommandProcessor.prototype.changeBreakPointRequest_ = function(request, response) {
+  // Check for legal request.
+  if (!request.arguments) {
+    response.failed('Missing arguments');
+    return;
+  }
+
+  // Pull out arguments.
+  var break_point = %ToNumber(request.arguments.breakpoint);
+  var enabled = request.arguments.enabled;
+  var condition = request.arguments.condition;
+  var ignoreCount = request.arguments.ignoreCount;
+
+  // Check for legal arguments.
+  if (!break_point) {
+    response.failed('Missing argument "breakpoint"');
+    return;
+  }
+
+  // Change enabled state if supplied.
+  if (!IS_UNDEFINED(enabled)) {
+    if (enabled) {
+      Debug.enableBreakPoint(break_point);
+    } else {
+      Debug.disableBreakPoint(break_point);
+    }
+  }
+
+  // Change condition if supplied
+  if (!IS_UNDEFINED(condition)) {
+    Debug.changeBreakPointCondition(break_point, condition);
+  }
+
+  // Change ignore count if supplied
+  if (!IS_UNDEFINED(ignoreCount)) {
+    Debug.changeBreakPointIgnoreCount(break_point, ignoreCount);
+  }
+}
+
+
+DebugCommandProcessor.prototype.clearBreakPointGroupRequest_ = function(request, response) {
+  // Check for legal request.
+  if (!request.arguments) {
+    response.failed('Missing arguments');
+    return;
+  }
+
+  // Pull out arguments.
+  var group_id = request.arguments.groupId;
+
+  // Check for legal arguments.
+  if (!group_id) {
+    response.failed('Missing argument "groupId"');
+    return;
+  }
+
+  var cleared_break_points = [];
+  var new_script_break_points = [];
+  for (var i = 0; i < script_break_points.length; i++) {
+    var next_break_point = script_break_points[i];
+    if (next_break_point.groupId() == group_id) {
+      cleared_break_points.push(next_break_point.number());
+      next_break_point.clear();
+    } else {
+      new_script_break_points.push(next_break_point);
+    }
+  }
+  script_break_points = new_script_break_points;
+
+  // Add the cleared break point numbers to the response.
+  response.body = { breakpoints: cleared_break_points };
+}
+
+
+DebugCommandProcessor.prototype.clearBreakPointRequest_ = function(request, response) {
+  // Check for legal request.
+  if (!request.arguments) {
+    response.failed('Missing arguments');
+    return;
+  }
+
+  // Pull out arguments.
+  var break_point = %ToNumber(request.arguments.breakpoint);
+
+  // Check for legal arguments.
+  if (!break_point) {
+    response.failed('Missing argument "breakpoint"');
+    return;
+  }
+
+  // Clear break point.
+  Debug.clearBreakPoint(break_point);
+
+  // Add the cleared break point number to the response.
+  response.body = { breakpoint: break_point }
+}
+
+
+DebugCommandProcessor.prototype.backtraceRequest_ = function(request, response) {
+  // Get the number of frames.
+  var total_frames = this.exec_state_.frameCount();
+
+  // Create simple response if there are no frames.
+  if (total_frames == 0) {
+    response.body = {
+      totalFrames: total_frames
+    }
+    return;
+  }
+
+  // Default frame range to include in backtrace.
+  var from_index = 0
+  var to_index = kDefaultBacktraceLength;
+
+  // Get the range from the arguments.
+  if (request.arguments) {
+    if (request.arguments.fromFrame) {
+      from_index = request.arguments.fromFrame;
+    }
+    if (request.arguments.toFrame) {
+      to_index = request.arguments.toFrame;
+    }
+    if (request.arguments.bottom) {
+      var tmp_index = total_frames - from_index;
+      from_index = total_frames - to_index
+      to_index = tmp_index;
+    }
+    if (from_index < 0 || to_index < 0) {
+      return response.failed('Invalid frame number');
+    }
+  }
+
+  // Adjust the index.
+  to_index = Math.min(total_frames, to_index);
+
+  if (to_index <= from_index) {
+    var error = 'Invalid frame range';
+    return response.failed(error);
+  }
+
+  // Create the response body.
+  var frames = [];
+  for (var i = from_index; i < to_index; i++) {
+    frames.push(this.exec_state_.frame(i));
+  }
+  response.body = {
+    fromFrame: from_index,
+    toFrame: to_index,
+    totalFrames: total_frames,
+    frames: frames
+  }
+};
+
+
+DebugCommandProcessor.prototype.backtracec = function(cmd, args) {
+  return this.exec_state_.cframesValue();
+};
+
+
+DebugCommandProcessor.prototype.frameRequest_ = function(request, response) {
+  // No frames no source.
+  if (this.exec_state_.frameCount() == 0) {
+    return response.failed('No frames');
+  }
+
+  // With no arguments just keep the selected frame.
+  if (request.arguments) {
+    var index = request.arguments.number;
+    if (index < 0 || this.exec_state_.frameCount() <= index) {
+      return response.failed('Invalid frame number');
+    }
+
+    this.exec_state_.setSelectedFrame(request.arguments.number);
+  }
+  response.body = this.exec_state_.frame();
+};
+
+
+DebugCommandProcessor.prototype.frameForScopeRequest_ = function(request) {
+  // Get the frame for which the scope or scopes are requested. With no frameNumber
+  // argument use the currently selected frame.
+  if (request.arguments && !IS_UNDEFINED(request.arguments.frameNumber)) {
+    frame_index = request.arguments.frameNumber;
+    if (frame_index < 0 || this.exec_state_.frameCount() <= frame_index) {
+      return response.failed('Invalid frame number');
+    }
+    return this.exec_state_.frame(frame_index);
+  } else {
+    return this.exec_state_.frame();
+  }
+}
+
+
+DebugCommandProcessor.prototype.scopesRequest_ = function(request, response) {
+  // No frames no scopes.
+  if (this.exec_state_.frameCount() == 0) {
+    return response.failed('No scopes');
+  }
+
+  // Get the frame for which the scopes are requested.
+  var frame = this.frameForScopeRequest_(request);
+
+  // Fill all scopes for this frame.
+  var total_scopes = frame.scopeCount();
+  var scopes = [];
+  for (var i = 0; i < total_scopes; i++) {
+    scopes.push(frame.scope(i));
+  }
+  response.body = {
+    fromScope: 0,
+    toScope: total_scopes,
+    totalScopes: total_scopes,
+    scopes: scopes
+  }
+};
+
+
+DebugCommandProcessor.prototype.scopeRequest_ = function(request, response) {
+  // No frames no scopes.
+  if (this.exec_state_.frameCount() == 0) {
+    return response.failed('No scopes');
+  }
+
+  // Get the frame for which the scope is requested.
+  var frame = this.frameForScopeRequest_(request);
+
+  // With no scope argument just return top scope.
+  var scope_index = 0;
+  if (request.arguments && !IS_UNDEFINED(request.arguments.number)) {
+    scope_index = %ToNumber(request.arguments.number);
+    if (scope_index < 0 || frame.scopeCount() <= scope_index) {
+      return response.failed('Invalid scope number');
+    }
+  }
+
+  response.body = frame.scope(scope_index);
+};
+
+
+DebugCommandProcessor.prototype.evaluateRequest_ = function(request, response) {
+  if (!request.arguments) {
+    return response.failed('Missing arguments');
+  }
+
+  // Pull out arguments.
+  var expression = request.arguments.expression;
+  var frame = request.arguments.frame;
+  var global = request.arguments.global;
+  var disable_break = request.arguments.disable_break;
+
+  // The expression argument could be an integer so we convert it to a
+  // string.
+  try {
+    expression = String(expression);
+  } catch(e) {
+    return response.failed('Failed to convert expression argument to string');
+  }
+
+  // Check for legal arguments.
+  if (!IS_UNDEFINED(frame) && global) {
+    return response.failed('Arguments "frame" and "global" are exclusive');
+  }
+
+  // Global evaluate.
+  if (global) {
+    // Evaluate in the global context.
+    response.body =
+        this.exec_state_.evaluateGlobal(expression, Boolean(disable_break));
+    return;
+  }
+
+  // Default value for disable_break is true.
+  if (IS_UNDEFINED(disable_break)) {
+    disable_break = true;
+  }
+
+  // No frames no evaluate in frame.
+  if (this.exec_state_.frameCount() == 0) {
+    return response.failed('No frames');
+  }
+
+  // Check whether a frame was specified.
+  if (!IS_UNDEFINED(frame)) {
+    var frame_number = %ToNumber(frame);
+    if (frame_number < 0 || frame_number >= this.exec_state_.frameCount()) {
+      return response.failed('Invalid frame "' + frame + '"');
+    }
+    // Evaluate in the specified frame.
+    response.body = this.exec_state_.frame(frame_number).evaluate(
+        expression, Boolean(disable_break));
+    return;
+  } else {
+    // Evaluate in the selected frame.
+    response.body = this.exec_state_.frame().evaluate(
+        expression, Boolean(disable_break));
+    return;
+  }
+};
+
+
+DebugCommandProcessor.prototype.lookupRequest_ = function(request, response) {
+  if (!request.arguments) {
+    return response.failed('Missing arguments');
+  }
+
+  // Pull out arguments.
+  var handles = request.arguments.handles;
+
+  // Check for legal arguments.
+  if (IS_UNDEFINED(handles)) {
+    return response.failed('Argument "handles" missing');
+  }
+
+  // Set 'includeSource' option for script lookup.
+  if (!IS_UNDEFINED(request.arguments.includeSource)) {
+    includeSource = %ToBoolean(request.arguments.includeSource);
+    response.setOption('includeSource', includeSource);
+  }
+
+  // Lookup handles.
+  var mirrors = {};
+  for (var i = 0; i < handles.length; i++) {
+    var handle = handles[i];
+    var mirror = LookupMirror(handle);
+    if (!mirror) {
+      return response.failed('Object #' + handle + '# not found');
+    }
+    mirrors[handle] = mirror;
+  }
+  response.body = mirrors;
+};
+
+
+DebugCommandProcessor.prototype.referencesRequest_ =
+    function(request, response) {
+  if (!request.arguments) {
+    return response.failed('Missing arguments');
+  }
+
+  // Pull out arguments.
+  var type = request.arguments.type;
+  var handle = request.arguments.handle;
+
+  // Check for legal arguments.
+  if (IS_UNDEFINED(type)) {
+    return response.failed('Argument "type" missing');
+  }
+  if (IS_UNDEFINED(handle)) {
+    return response.failed('Argument "handle" missing');
+  }
+  if (type != 'referencedBy' && type != 'constructedBy') {
+    return response.failed('Invalid type "' + type + '"');
+  }
+
+  // Lookup handle and return objects with references the object.
+  var mirror = LookupMirror(handle);
+  if (mirror) {
+    if (type == 'referencedBy') {
+      response.body = mirror.referencedBy();
+    } else {
+      response.body = mirror.constructedBy();
+    }
+  } else {
+    return response.failed('Object #' + handle + '# not found');
+  }
+};
+
+
+DebugCommandProcessor.prototype.sourceRequest_ = function(request, response) {
+  // No frames no source.
+  if (this.exec_state_.frameCount() == 0) {
+    return response.failed('No source');
+  }
+
+  var from_line;
+  var to_line;
+  var frame = this.exec_state_.frame();
+  if (request.arguments) {
+    // Pull out arguments.
+    from_line = request.arguments.fromLine;
+    to_line = request.arguments.toLine;
+
+    if (!IS_UNDEFINED(request.arguments.frame)) {
+      var frame_number = %ToNumber(request.arguments.frame);
+      if (frame_number < 0 || frame_number >= this.exec_state_.frameCount()) {
+        return response.failed('Invalid frame "' + frame + '"');
+      }
+      frame = this.exec_state_.frame(frame_number);
+    }
+  }
+
+  // Get the script selected.
+  var script = frame.func().script();
+  if (!script) {
+    return response.failed('No source');
+  }
+
+  // Get the source slice and fill it into the response.
+  var slice = script.sourceSlice(from_line, to_line);
+  if (!slice) {
+    return response.failed('Invalid line interval');
+  }
+  response.body = {};
+  response.body.source = slice.sourceText();
+  response.body.fromLine = slice.from_line;
+  response.body.toLine = slice.to_line;
+  response.body.fromPosition = slice.from_position;
+  response.body.toPosition = slice.to_position;
+  response.body.totalLines = script.lineCount();
+};
+
+
+DebugCommandProcessor.prototype.scriptsRequest_ = function(request, response) {
+  var types = ScriptTypeFlag(Debug.ScriptType.Normal);
+  var includeSource = false;
+  var idsToInclude = null;
+  if (request.arguments) {
+    // Pull out arguments.
+    if (!IS_UNDEFINED(request.arguments.types)) {
+      types = %ToNumber(request.arguments.types);
+      if (isNaN(types) || types < 0) {
+        return response.failed('Invalid types "' + request.arguments.types + '"');
+      }
+    }
+    
+    if (!IS_UNDEFINED(request.arguments.includeSource)) {
+      includeSource = %ToBoolean(request.arguments.includeSource);
+      response.setOption('includeSource', includeSource);
+    }
+    
+    if (IS_ARRAY(request.arguments.ids)) {
+      idsToInclude = {};
+      var ids = request.arguments.ids;
+      for (var i = 0; i < ids.length; i++) {
+        idsToInclude[ids[i]] = true;
+      }
+    }
+  }
+
+  // Collect all scripts in the heap.
+  var scripts = %DebugGetLoadedScripts();
+
+  response.body = [];
+
+  for (var i = 0; i < scripts.length; i++) {
+    if (idsToInclude && !idsToInclude[scripts[i].id]) {
+      continue;
+    }
+    if (types & ScriptTypeFlag(scripts[i].type)) {
+      response.body.push(MakeMirror(scripts[i]));
+    }
+  }
+};
+
+
+DebugCommandProcessor.prototype.threadsRequest_ = function(request, response) {
+  // Get the number of threads.
+  var total_threads = this.exec_state_.threadCount();
+
+  // Get information for all threads.
+  var threads = [];
+  for (var i = 0; i < total_threads; i++) {
+    var details = %GetThreadDetails(this.exec_state_.break_id, i);
+    var thread_info = { current: details[0],
+                        id: details[1]
+                      }
+    threads.push(thread_info);
+  }
+
+  // Create the response body.
+  response.body = {
+    totalThreads: total_threads,
+    threads: threads
+  }
+};
+
+
+DebugCommandProcessor.prototype.suspendRequest_ = function(request, response) {
+  response.running = false;
+};
+
+
+DebugCommandProcessor.prototype.versionRequest_ = function(request, response) {
+  response.body = {
+    V8Version: %GetV8Version()
+  }
+};
+
+
+DebugCommandProcessor.prototype.profileRequest_ = function(request, response) {
+  if (!request.arguments) {
+    return response.failed('Missing arguments');
+  }
+  var modules = parseInt(request.arguments.modules);
+  if (isNaN(modules)) {
+    return response.failed('Modules is not an integer');
+  }
+  if (request.arguments.command == 'resume') {
+    %ProfilerResume(modules);
+  } else if (request.arguments.command == 'pause') {
+    %ProfilerPause(modules);
+  } else {
+    return response.failed('Unknown command');
+  }
+  response.body = {};
+};
+
+
+// Check whether the previously processed command caused the VM to become
+// running.
+DebugCommandProcessor.prototype.isRunning = function() {
+  return this.running_;
+}
+
+
+DebugCommandProcessor.prototype.systemBreak = function(cmd, args) {
+  return %SystemBreak();
+};
+
+
+function NumberToHex8Str(n) {
+  var r = "";
+  for (var i = 0; i < 8; ++i) {
+    var c = hexCharArray[n & 0x0F];  // hexCharArray is defined in uri.js
+    r = c + r;
+    n = n >>> 4;
+  }
+  return r;
+};
+
+DebugCommandProcessor.prototype.formatCFrames = function(cframes_value) {
+  var result = "";
+  if (cframes_value == null || cframes_value.length == 0) {
+    result += "(stack empty)";
+  } else {
+    for (var i = 0; i < cframes_value.length; ++i) {
+      if (i != 0) result += "\n";
+      result += this.formatCFrame(cframes_value[i]);
+    }
+  }
+  return result;
+};
+
+
+DebugCommandProcessor.prototype.formatCFrame = function(cframe_value) {
+  var result = "";
+  result += "0x" + NumberToHex8Str(cframe_value.address);
+  if (!IS_UNDEFINED(cframe_value.text)) {
+    result += " " + cframe_value.text;
+  }
+  return result;
+}
+
+
+/**
+ * Convert an Object to its debugger protocol representation. The representation
+ * may be serilized to a JSON object using JSON.stringify().
+ * This implementation simply runs through all string property names, converts
+ * each property value to a protocol value and adds the property to the result
+ * object. For type "object" the function will be called recursively. Note that
+ * circular structures will cause infinite recursion.
+ * @param {Object} object The object to format as protocol object.
+ * @param {MirrorSerializer} mirror_serializer The serializer to use if any
+ *     mirror objects are encountered.
+ * @return {Object} Protocol object value.
+ */
+function ObjectToProtocolObject_(object, mirror_serializer) {
+  var content = {};
+  for (var key in object) {
+    // Only consider string keys.
+    if (typeof key == 'string') {
+      // Format the value based on its type.
+      var property_value_json = ValueToProtocolValue_(object[key],
+                                                      mirror_serializer);
+      // Add the property if relevant.
+      if (!IS_UNDEFINED(property_value_json)) {
+        content[key] = property_value_json;
+      }
+    }
+  }
+  
+  return content;
+}
+
+
+/**
+ * Convert an array to its debugger protocol representation. It will convert
+ * each array element to a protocol value.
+ * @param {Array} array The array to format as protocol array.
+ * @param {MirrorSerializer} mirror_serializer The serializer to use if any
+ *     mirror objects are encountered.
+ * @return {Array} Protocol array value.
+ */
+function ArrayToProtocolArray_(array, mirror_serializer) {
+  var json = [];
+  for (var i = 0; i < array.length; i++) {
+    json.push(ValueToProtocolValue_(array[i], mirror_serializer));
+  }
+  return json;
+}
+
+
+/**
+ * Convert a value to its debugger protocol representation. 
+ * @param {*} value The value to format as protocol value.
+ * @param {MirrorSerializer} mirror_serializer The serializer to use if any
+ *     mirror objects are encountered.
+ * @return {*} Protocol value.
+ */
+function ValueToProtocolValue_(value, mirror_serializer) {
+  // Format the value based on its type.
+  var json;
+  switch (typeof value) {
+    case 'object':
+      if (value instanceof Mirror) {
+        json = mirror_serializer.serializeValue(value);
+      } else if (IS_ARRAY(value)){
+        json = ArrayToProtocolArray_(value, mirror_serializer);
+      } else {
+        json = ObjectToProtocolObject_(value, mirror_serializer);
+      }
+      break;
+
+    case 'boolean':
+    case 'string':
+    case 'number':
+      json = value;
+      break
+
+    default:
+      json = null;
+  }
+  return json;
+}