Added command line debugger to D8 shell....

src/d8.js

 // Copyright 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
@@ skipping 13 matching lines @@
 // 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.
 
 // How crappy is it that I have to implement completely basic stuff
 // like this myself?  Answer: very.
 String.prototype.startsWith = function (str) {
   if (str.length > this.length)
     return false;
   return this.substr(0, str.length) == str;
-};
+}
+
+function log10(num) {
+  return Math.log(num)/Math.log(10);
+}
 
 function ToInspectableObject(obj) {
   if (!obj && typeof obj === 'object') {
     return void 0;
   } else {
     return Object(obj);
   }
 }
 
 function GetCompletions(global, last, full) {
@@ skipping 16 matching lines @@
     var properties = mirror.properties();
     for (var i = 0; i < properties.length; i++) {
       var name = properties[i].name();
       if (typeof name === 'string' && name.startsWith(last))
         result.push(name);
     }
     current = ToInspectableObject(current.__proto__);
   }
   return result;
 }
+
+
+// Global object holding debugger related constants and state.
+const Debug = {};
+
+
+// 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 };
+
+
+// The different types of scripts matching enum ScriptType in objects.h.
+Debug.ScriptType = { Native: 0,
+                     Extension: 1,
+                     Normal: 2 };
+
+
+// Current debug state.
+const kNoFrame = -1;
+Debug.State = {
+  currentFrame: kNoFrame,
+  currentSourceLine: -1
+}
+
+
+function DebugEventToText(event) {
+  if (event.eventType() == 1) {
+    // Build the break details.
+    var details = '';
+    if (event.breakPointsHit()) {
+      details += 'breakpoint';
+      if (event.breakPointsHit().length > 1) {
+        details += 's';
+      }
+      details += ' #';
+      for (var i = 0; i < event.breakPointsHit().length; i++) {
+        if (i > 0) {
+          details += ', #';
+        }
+        // Find the break point number. For break points originating from a
+        // script break point display the script break point number.
+        var break_point = event.breakPointsHit()[i];
+        var script_break_point = break_point.script_break_point();
+        if (script_break_point) {
+          details += script_break_point.number();
+        } else {
+          details += break_point.number();
+        }
+      }
+    } else {
+      details += 'break';
+    }
+    details += ' in ';
+    details += event.executionState().frame(0).invocationText();
+    details += ' at ';
+    details += event.executionState().frame(0).sourceAndPositionText();
+    details += '\n'
+    if (event.func().script()) {
+      details += FrameSourceUnderline(event.executionState().frame(0));
+    }
+    Debug.State.currentSourceLine =
+        event.executionState().frame(0).sourceLine();
+    Debug.State.currentFrame = 0;
+    return details;
+  } else if (event.eventType() == 2) {
+    var details = '';
+    if (event.uncaught_) {
+      details += 'Uncaught: ';
+    } else {
+      details += 'Exception: ';
+    }
+
+    details += '"';
+    details += event.exception();
+    details += '"';
+    if (event.executionState().frameCount() > 0) {
+      details += '"';
+      details += event.exception();
+      details += ' at ';
+      details += event.executionState().frame(0).sourceAndPositionText();
+      details += '\n';
+      details += FrameSourceUnderline(event.executionState().frame(0));
+      Debug.State.currentSourceLine =
+          event.executionState().frame(0).sourceLine();
+      Debug.State.currentFrame = 0;
+    } else {
+      details += ' (empty stack)';
+      Debug.State.currentSourceLine = -1;
+      Debug.State.currentFrame = kNoFrame;
+    }
+
+    return details;
+  }
+
+  return 'Unknown debug event ' + event.eventType();
+};
+
+
+function SourceUnderline(source_text, position) {
+  if (!source_text) {
+    return;
+  }
+
+  // Create an underline with a caret pointing to the source position. If the           
+  // source contains a tab character the underline will have a tab character in         
+  // the same place otherwise the underline will have a space character.                
+  var underline = '';
+  for (var i = 0; i < position; i++) {
+    if (source_text[i] == '\t') {
+      underline += '\t';
+    } else {
+      underline += ' ';
+    }
+  }
+  underline += '^';
+
+  // Return the source line text with the underline beneath.
+  return source_text + '\n' + underline;
+};
+
+
+function FrameSourceUnderline(frame) {          
+  var location = frame.sourceLocation();
+  if (location) {
+    return SourceUnderline(location.sourceText(), location.position - location.start);
+  }
+};
+
+
+// Converts a text command to a JSON request.
+function DebugCommandToJSONRequest(cmd_line) {
+  return new DebugRequest(cmd_line).JSONRequest();
+};
+
+
+function DebugRequest(cmd_line) {
+  // If the very first character is a { assume that a JSON request have been
+  // entered as a command. Converting that to a JSON request is trivial.
+  if (cmd_line && cmd_line.length > 0 && cmd_line.charAt(0) == '{') {
+    this.request_ = cmd_line;
+    return;
+  }
+
+  // Trim string for leading and trailing whitespace.
+  cmd_line = cmd_line.replace(/^\s+|\s+$/g, '');
+
+  // Find the command.
+  var pos = cmd_line.indexOf(' ');
+  var cmd;
+  var args;
+  if (pos == -1) {
+    cmd = cmd_line;
+    args = '';
+  } else {
+    cmd = cmd_line.slice(0, pos);
+    args = cmd_line.slice(pos).replace(/^\s+|\s+$/g, '');
+  }
+
+  // Switch on command.
+  if (cmd == 'continue' || cmd == 'c') {
+    this.request_ = this.continueCommandToJSONRequest_(args);
+  } else if (cmd == 'step' || cmd == 's') {
+    this.request_ = this.stepCommandToJSONRequest_(args);
+  } else if (cmd == 'backtrace' || cmd == 'bt') {
+    this.request_ = this.backtraceCommandToJSONRequest_(args);
+  } else if (cmd == 'frame' || cmd == 'f') {
+    this.request_ = this.frameCommandToJSONRequest_(args);
+  } else if (cmd == 'print' || cmd == 'p') {
+    this.request_ = this.printCommandToJSONRequest_(args);
+  } else if (cmd == 'source') {
+    this.request_ = this.sourceCommandToJSONRequest_(args);
+  } else if (cmd == 'scripts') {
+    this.request_ = this.scriptsCommandToJSONRequest_(args);
+  } else if (cmd == 'break' || cmd == 'b') {
+    this.request_ = this.breakCommandToJSONRequest_(args);
+  } else if (cmd == 'clear') {
+    this.request_ = this.clearCommandToJSONRequest_(args);
+  } else if (cmd == 'help' || cmd == '?') {
+    this.helpCommand_(args);
+    // Return null to indicate no JSON to send (command handled internally). 
+    this.request_ = void 0;  
+  } else {
+    throw new Error('Unknown command "' + cmd + '"');
+  }
+}
+
+DebugRequest.prototype.JSONRequest = function() {
+  return this.request_;
+}
+
+
+function RequestPacket(command) {
+  this.seq = 0;
+  this.type = 'request';
+  this.command = command;
+}
+
+
+RequestPacket.prototype.toJSONProtocol = function() {
+  // Encode the protocol header.
+  var json = '{';
+  json += '"seq":' + this.seq;
+  json += ',"type":"' + this.type + '"';
+  if (this.command) {
+    json += ',"command":' + StringToJSON_(this.command);
+  }
+  if (this.arguments) {
+    json += ',"arguments":';
+    // Encode the arguments part.
+    if (this.arguments.toJSONProtocol) {
+      json += this.arguments.toJSONProtocol()
+    } else {
+      json += SimpleObjectToJSON_(this.arguments);
+    }
+  }
+  json += '}';
+  return json;
+}
+
+
+DebugRequest.prototype.createRequest = function(command) {
+  return new RequestPacket(command);
+};
+
+
+// Create a JSON request for the continue command.
+DebugRequest.prototype.continueCommandToJSONRequest_ = function(args) {
+  var request = this.createRequest('continue');
+  return request.toJSONProtocol();
+};
+
+
+// Create a JSON request for the step command.
+DebugRequest.prototype.stepCommandToJSONRequest_ = function(args) {
+  // Requesting a step is through the continue command with additional
+  // arguments.
+  var request = this.createRequest('continue');
+  request.arguments = {};
+
+  // Process arguments if any.
+  if (args && args.length > 0) {
+    args = args.split(/\s*[ ]+\s*/g);
+
+    if (args.length > 2) {
+      throw new Error('Invalid step arguments.');
+    }
+
+    if (args.length > 0) {
+      // Get step count argument if any.
+      if (args.length == 2) {
+        var stepcount = parseInt(args[1]);
+        if (isNaN(stepcount) || stepcount <= 0) {
+          throw new Error('Invalid step count argument "' + args[0] + '".');
+        }
+        request.arguments.stepcount = stepcount;
+      }
+
+      // Get the step action.
+      if (args[0] == 'in' || args[0] == 'i') {
+        request.arguments.stepaction = 'in';
+      } else if (args[0] == 'min' || args[0] == 'm') {
+        request.arguments.stepaction = 'min';
+      } else if (args[0] == 'next' || args[0] == 'n') {
+        request.arguments.stepaction = 'next';
+      } else if (args[0] == 'out' || args[0] == 'o') {
+        request.arguments.stepaction = 'out';
+      } else {
+        throw new Error('Invalid step argument "' + args[0] + '".');
+      }
+    }
+  } else {
+    // Default is step next.
+    request.arguments.stepaction = 'next';
+  }
+
+  return request.toJSONProtocol();
+};
+
+
+// Create a JSON request for the backtrace command.
+DebugRequest.prototype.backtraceCommandToJSONRequest_ = function(args) {
+  // Build a backtrace request from the text command.
+  var request = this.createRequest('backtrace');
+  args = args.split(/\s*[ ]+\s*/g);
+  if (args.length == 2) {
+    request.arguments = {};
+    var fromFrame = parseInt(args[0]);
+    var toFrame = parseInt(args[1]);
+    if (isNaN(fromFrame) || fromFrame < 0) {
+      throw new Error('Invalid start frame argument "' + args[0] + '".');
+    }
+    if (isNaN(toFrame) || toFrame < 0) {
+      throw new Error('Invalid end frame argument "' + args[1] + '".');
+    }
+    if (fromFrame > toFrame) {
+      throw new Error('Invalid arguments start frame cannot be larger ' +
+                      'than end frame.');
+    }
+    request.arguments.fromFrame = fromFrame;
+    request.arguments.toFrame = toFrame + 1;
+  }
+  return request.toJSONProtocol();
+};
+
+
+// Create a JSON request for the frame command.
+DebugRequest.prototype.frameCommandToJSONRequest_ = function(args) {
+  // Build a frame request from the text command.
+  var request = this.createRequest('frame');
+  args = args.split(/\s*[ ]+\s*/g);
+  if (args.length > 0 && args[0].length > 0) {
+    request.arguments = {};
+    request.arguments.number = args[0];
+  }
+  return request.toJSONProtocol();
+};
+
+
+// Create a JSON request for the print command.
+DebugRequest.prototype.printCommandToJSONRequest_ = function(args) {
+  // Build a evaluate request from the text command.
+  var request = this.createRequest('evaluate');
+  if (args.length == 0) {
+    throw new Error('Missing expression.');
+  }
+
+  request.arguments = {};
+  request.arguments.expression = args;
+
+  return request.toJSONProtocol();
+};
+
+
+// Create a JSON request for the source command.
+DebugRequest.prototype.sourceCommandToJSONRequest_ = function(args) {
+  // Build a evaluate request from the text command.
+  var request = this.createRequest('source');
+
+  // Default is ten lines starting five lines before the current location.
+  var from = Debug.State.currentSourceLine - 5;
+  var lines = 10;
+
+  // Parse the arguments.
+  args = args.split(/\s*[ ]+\s*/g);
+  if (args.length > 1 && args[0].length > 0 && args[1].length > 0) {
+    from = parseInt(args[0]) - 1;
+    lines = parseInt(args[1]);
+  } else if (args.length > 0 && args[0].length > 0) {
+    from = parseInt(args[0]) - 1;
+  }
+
+  if (from < 0) from = 0;
+  if (lines < 0) lines = 10;
+
+  // Request source arround current source location.
+  request.arguments = {};
+  request.arguments.fromLine = from;
+  request.arguments.toLine = from + lines;
+
+  return request.toJSONProtocol();
+};
+
+
+// Create a JSON request for the scripts command.
+DebugRequest.prototype.scriptsCommandToJSONRequest_ = function(args) {
+  // Build a evaluate request from the text command.
+  var request = this.createRequest('scripts');
+
+  // Process arguments if any.
+  if (args && args.length > 0) {
+    args = args.split(/\s*[ ]+\s*/g);
+
+    if (args.length > 1) {
+      throw new Error('Invalid scripts arguments.');
+    }
+
+    request.arguments = {};
+    if (args[0] == 'natives') {
+      request.arguments.types = ScriptTypeFlag(Debug.ScriptType.Native);
+    } else if (args[0] == 'extensions') {
+      request.arguments.types = ScriptTypeFlag(Debug.ScriptType.Extension);
+    } else if (args[0] == 'all') {
+      request.arguments.types =
+          ScriptTypeFlag(Debug.ScriptType.Normal) |
+          ScriptTypeFlag(Debug.ScriptType.Native) |
+          ScriptTypeFlag(Debug.ScriptType.Extension);
+    } else {
+      throw new Error('Invalid argument "' + args[0] + '".');
+    }
+  }
+
+  return request.toJSONProtocol();
+};
+
+
+// Create a JSON request for the break command.
+DebugRequest.prototype.breakCommandToJSONRequest_ = function(args) {
+  // Build a evaluate request from the text command.
+  var request = this.createRequest('setbreakpoint');
+
+  // Process arguments if any.
+  if (args && args.length > 0) {
+    var target = args;
+    var condition;
+
+    var pos = args.indexOf(' ');
+    if (pos > 0) {
+      target = args.substring(0, pos);
+      condition = args.substring(pos + 1, args.length);
+    }
+
+    request.arguments = {};
+    request.arguments.type = 'function';
+    request.arguments.target = target;
+    request.arguments.condition = condition;
+  } else {
+    throw new Error('Invalid break arguments.');
+  }
+
+  return request.toJSONProtocol();
+};
+
+
+// Create a JSON request for the clear command.
+DebugRequest.prototype.clearCommandToJSONRequest_ = function(args) {
+  // Build a evaluate request from the text command.
+  var request = this.createRequest('clearbreakpoint');
+
+  // Process arguments if any.
+  if (args && args.length > 0) {
+    request.arguments = {};
+    request.arguments.breakpoint = parseInt(args);
+  } else {
+    throw new Error('Invalid break arguments.');
+  }
+
+  return request.toJSONProtocol();
+};
+
+
+// Create a JSON request for the break command.
+DebugRequest.prototype.helpCommand_ = function(args) {
+  // Help os quite simple.
+  if (args && args.length > 0) {
+    print('warning: arguments to \'help\' are ignored');
+  }
+
+  print('break location [condition]');
+  print('clear <breakpoint #>');
+  print('backtrace [from frame #] [to frame #]]');
+  print('frame <frame #>');
+  print('step [in | next | out| min [step count]]');
+  print('print <expression>');
+  print('source [from line [num lines]]');
+  print('scripts');
+  print('continue');
+  print('help');
+}
+
+
+// Convert a JSON response to text for display in a text based debugger.
+function DebugResponseDetails(json_response) {
+  details = {text:'', running:false}
+
+  try {
+    // Convert the JSON string to an object.
+    response = eval('(' + json_response + ')');
+
+    if (!response.success) {
+      details.text = response.message;
+      return details;
+    }
+
+    // Get the running state.
+    details.running = response.running;
+
+    if (response.command == 'setbreakpoint') {
+      var body = response.body;
+      result = 'set breakpoint #';
+      result += body.breakpoint;
+      details.text = result;
+    } else if (response.command == 'clearbreakpoint') {
+      var body = response.body;
+      result = 'cleared breakpoint #';
+      result += body.breakpoint;
+      details.text = result;
+    } else if (response.command == 'backtrace') {
+      var body = response.body;
+      if (body.totalFrames == 0) {
+        result = '(empty stack)';
+      } else {
+        var result = 'Frames #' + body.fromFrame + ' to #' +
+            (body.toFrame - 1) + ' of ' + body.totalFrames + '\n';
+        for (i = 0; i < body.frames.length; i++) {
+          if (i != 0) result += '\n';
+          result += body.frames[i].text;
+        }
+      }
+      details.text = result;
+    } else if (response.command == 'frame') {
+      details.text = SourceUnderline(response.body.sourceLineText,
+                                     response.body.column);
+      Debug.State.currentSourceLine = response.body.line;
+      Debug.State.currentFrame = response.body.index;
+    } else if (response.command == 'evaluate') {
+      details.text =  response.body.text;
+    } else if (response.command == 'source') {
+      // Get the source from the response.
+      var source = response.body.source;
+      var from_line = response.body.fromLine + 1;
+      var lines = source.split('\n');
+      var maxdigits = 1 + Math.floor(log10(from_line + lines.length));
+      if (maxdigits < 3) {
+        maxdigits = 3;
+      }
+      var result = '';
+      for (var num = 0; num < lines.length; num++) {
+        // Check if there's an extra newline at the end.
+        if (num == (lines.length - 1) && lines[num].length == 0) {
+          break;
+        }
+
+        var current_line = from_line + num;
+        spacer = maxdigits - (1 + Math.floor(log10(current_line)));
+        if (current_line == Debug.State.currentSourceLine + 1) {
+          for (var i = 0; i < maxdigits; i++) {
+            result += '>';
+          }
+          result += '  ';
+        } else {
+          for (var i = 0; i < spacer; i++) {
+            result += ' ';
+          }
+          result += current_line + ': ';
+        }
+        result += lines[num];
+        result += '\n';
+      }
+      details.text = result;
+    } else if (response.command == 'scripts') {
+      var result = '';
+      for (i = 0; i < response.body.length; i++) {
+        if (i != 0) result += '\n';
+        if (response.body[i].name) {
+          result += response.body[i].name;
+        } else {
+          result += '[unnamed] ';
+          var sourceStart = response.body[i].sourceStart;
+          if (sourceStart.length > 40) {
+            sourceStart = sourceStart.substring(0, 37) + '...';
+          }
+          result += sourceStart;
+        }
+        result += ' (lines: ';
+        result += response.body[i].sourceLines;
+        result += ', length: ';
+        result += response.body[i].sourceLength;
+        if (response.body[i].type == Debug.ScriptType.Native) {
+          result += ', native';
+        } else if (response.body[i].type == Debug.ScriptType.Extension) {
+          result += ', extension';
+        }
+        result += ')';
+      }
+      details.text = result;
+    }
+  } catch (e) {
+    details.text = 'Error: "' + e + '" formatting response';
+  }
+  
+  return details;
+};
+
+
+function MakeJSONPair_(name, value) {
+  return '"' + name + '":' + value;
+}
+
+
+function ArrayToJSONObject_(content) {
+  return '{' + content.join(',') + '}';
+}
+
+
+function ArrayToJSONArray_(content) {
+  return '[' + content.join(',') + ']';
+}
+
+
+function BooleanToJSON_(value) {
+  return String(value); 
+}
+
+
+function NumberToJSON_(value) {
+  return String(value); 
+}
+
+
+// Mapping of some control characters to avoid the \uXXXX syntax for most
+// commonly used control cahracters.
+const ctrlCharMap_ = {
+  '\b': '\\b',
+  '\t': '\\t',
+  '\n': '\\n',
+  '\f': '\\f',
+  '\r': '\\r',
+  '"' : '\\"',
+  '\\': '\\\\'
+};
+
+
+// Regular expression testing for ", \ and control characters (0x00 - 0x1F).
+const ctrlCharTest_ = new RegExp('["\\\\\x00-\x1F]');
+
+
+// Regular expression matching ", \ and control characters (0x00 - 0x1F)
+// globally.
+const ctrlCharMatch_ = new RegExp('["\\\\\x00-\x1F]', 'g');
+
+
+/**
+ * Convert a String to its JSON representation (see http://www.json.org/). To
+ * avoid depending on the String object this method calls the functions in
+ * string.js directly and not through the value.
+ * @param {String} value The String value to format as JSON
+ * @return {string} JSON formatted String value
+ */
+function StringToJSON_(value) {
+  // Check for" , \ and control characters (0x00 - 0x1F). No need to call
+  // RegExpTest as ctrlchar is constructed using RegExp.
+  if (ctrlCharTest_.test(value)) {
+    // Replace ", \ and control characters (0x00 - 0x1F).
+    return '"' +
+      value.replace(ctrlCharMatch_, function (char) {
+        // Use charmap if possible.
+        var mapped = ctrlCharMap_[char];
+        if (mapped) return mapped;
+        mapped = char.charCodeAt();
+        // Convert control character to unicode escape sequence.
+        return '\\u00' +
+          '0' + // TODO %NumberToRadixString(Math.floor(mapped / 16), 16) +
+          '0' // TODO %NumberToRadixString(mapped % 16, 16);
+      })
+    + '"';
+  }
+
+  // Simple string with no special characters.
+  return '"' + value + '"';
+}
+
+
+/**
+ * Convert a Date to ISO 8601 format. To avoid depending on the Date object
+ * this method calls the functions in date.js directly and not through the
+ * value.
+ * @param {Date} value The Date value to format as JSON
+ * @return {string} JSON formatted Date value
+ */
+function DateToISO8601_(value) {
+  function f(n) {
+    return n < 10 ? '0' + n : n;
+  }
+  function g(n) {
+    return n < 10 ? '00' + n : n < 100 ? '0' + n : n;
+  }
+  return builtins.GetUTCFullYearFrom(value)         + '-' +
+          f(builtins.GetUTCMonthFrom(value) + 1)    + '-' +
+          f(builtins.GetUTCDateFrom(value))         + 'T' +
+          f(builtins.GetUTCHoursFrom(value))        + ':' +
+          f(builtins.GetUTCMinutesFrom(value))      + ':' +
+          f(builtins.GetUTCSecondsFrom(value))      + '.' +
+          g(builtins.GetUTCMillisecondsFrom(value)) + 'Z';
+}
+
+
+/**
+ * Convert a Date to ISO 8601 format. To avoid depending on the Date object
+ * this method calls the functions in date.js directly and not through the
+ * value.
+ * @param {Date} value The Date value to format as JSON
+ * @return {string} JSON formatted Date value
+ */
+function DateToJSON_(value) {
+  return '"' + DateToISO8601_(value) + '"';
+}
+
+
+/**
+ * Convert an Object to its JSON representation (see http://www.json.org/).
+ * This implementation simply runs through all string property names and adds
+ * each property to the JSON representation for some predefined types. For type
+ * "object" the function calls itself recursively unless the object has the
+ * function property "toJSONProtocol" in which case that is used. This is not
+ * a general implementation but sufficient for the debugger. Note that circular
+ * structures will cause infinite recursion.
+ * @param {Object} object The object to format as JSON
+ * @return {string} JSON formatted object value
+ */
+function SimpleObjectToJSON_(object) {
+  var content = [];
+  for (var key in object) {
+    // Only consider string keys.
+    if (typeof key == 'string') {
+      var property_value = object[key];
+
+      // Format the value based on its type.
+      var property_value_json;
+      switch (typeof property_value) {
+        case 'object':
+          if (typeof property_value.toJSONProtocol == 'function') {
+            property_value_json = property_value.toJSONProtocol(true)
+          } else if (property_value.constructor.name == 'Array'){
+            property_value_json = SimpleArrayToJSON_(property_value);
+          } else {
+            property_value_json = SimpleObjectToJSON_(property_value);
+          }
+          break;
+
+        case 'boolean':
+          property_value_json = BooleanToJSON_(property_value);
+          break;
+
+        case 'number':
+          property_value_json = NumberToJSON_(property_value);
+          break;
+
+        case 'string':
+          property_value_json = StringToJSON_(property_value);
+          break;
+
+        default:
+          property_value_json = null;
+      }
+
+      // Add the property if relevant.
+      if (property_value_json) {
+        content.push(StringToJSON_(key) + ':' + property_value_json);
+      }
+    }
+  }
+
+  // Make JSON object representation.
+  return '{' + content.join(',') + '}';
+}
+
+
+/**
+ * Convert an array to its JSON representation. This is a VERY simple
+ * implementation just to support what is needed for the debugger.
+ * @param {Array} arrya The array to format as JSON
+ * @return {string} JSON formatted array value
+ */
+function SimpleArrayToJSON_(array) {
+  // Make JSON array representation.
+  var json = '[';
+  for (var i = 0; i < array.length; i++) {
+    if (i != 0) {
+      json += ',';
+    }
+    var elem = array[i];
+    if (elem.toJSONProtocol) {
+      json += elem.toJSONProtocol(true)
+    } else if (typeof(elem) === 'object')  {
+      json += SimpleObjectToJSON_(elem);
+    } else if (typeof(elem) === 'boolean')  {
+      json += BooleanToJSON_(elem);
+    } else if (typeof(elem) === 'number')  {
+      json += NumberToJSON_(elem);
+    } else if (typeof(elem) === 'string')  {
+      json += StringToJSON_(elem);
+    } else {
+      json += elem;
+    }
+  }
+  json += ']';
+  return json;
+}