lodash/vendor/json3/lib/json3.js

/*! JSON v3.2.4 | http://bestiejs.github.com/json3 | Copyright 2012, Kit Cambridge | http://kit.mit-license.org */
;(function () {
  // Convenience aliases.
  var getClass = {}.toString, isProperty, forEach, undef;

  // Detect the `define` function exposed by asynchronous module loaders. The
  // strict `define` check is necessary for compatibility with `r.js`.
  var isLoader = typeof define === "function" && define.amd, JSON3 = !isLoader && typeof exports == "object" && exports;

  if (JSON3 || isLoader) {
    if (typeof JSON == "object" && JSON) {
      // Delegate to the native `stringify` and `parse` implementations in
      // asynchronous module loaders and CommonJS environments.
      if (isLoader) {
        JSON3 = JSON;
      } else {
        JSON3.stringify = JSON.stringify;
        JSON3.parse = JSON.parse;
      }
    } else if (isLoader) {
      JSON3 = this.JSON = {};
    }
  } else {
    // Export for web browsers and JavaScript engines.
    JSON3 = this.JSON || (this.JSON = {});
  }

  // Local variables.
  var Escapes, toPaddedString, quote, serialize;
  var fromCharCode, Unescapes, abort, lex, get, walk, update, Index, Source;

  // Test the `Date#getUTC*` methods. Based on work by @Yaffle.
  var isExtended = new Date(-3509827334573292), floor, Months, getDay;

  try {
    // The `getUTCFullYear`, `Month`, and `Date` methods return nonsensical
    // results for certain dates in Opera >= 10.53.
    isExtended = isExtended.getUTCFullYear() == -109252 && isExtended.getUTCMonth() === 0 && isExtended.getUTCDate() == 1 &&
      // Safari < 2.0.2 stores the internal millisecond time value correctly,
      // but clips the values returned by the date methods to the range of
      // signed 32-bit integers ([-2 ** 31, 2 ** 31 - 1]).
      isExtended.getUTCHours() == 10 && isExtended.getUTCMinutes() == 37 && isExtended.getUTCSeconds() == 6 && isExtended.getUTCMilliseconds() == 708;
  } catch (exception) {}

  // Internal: Determines whether the native `JSON.stringify` and `parse`
  // implementations are spec-compliant. Based on work by Ken Snyder.
  function has(name) {
    var stringifySupported, parseSupported, value, serialized = '{"A":[1,true,false,null,"\\u0000\\b\\n\\f\\r\\t"]}', all = name == "json";
    if (all || name == "json-stringify" || name == "json-parse") {
      // Test `JSON.stringify`.
      if (name == "json-stringify" || all) {
        if ((stringifySupported = typeof JSON3.stringify == "function" && isExtended)) {
          // A test function object with a custom `toJSON` method.
          (value = function () {
            return 1;
          }).toJSON = value;
          try {
            stringifySupported =
              // Firefox 3.1b1 and b2 serialize string, number, and boolean
              // primitives as object literals.
              JSON3.stringify(0) === "0" &&
              // FF 3.1b1, b2, and JSON 2 serialize wrapped primitives as object
              // literals.
              JSON3.stringify(new Number()) === "0" &&
              JSON3.stringify(new String()) == '""' &&
              // FF 3.1b1, 2 throw an error if the value is `null`, `undefined`, or
              // does not define a canonical JSON representation (this applies to
              // objects with `toJSON` properties as well, *unless* they are nested
              // within an object or array).
              JSON3.stringify(getClass) === undef &&
              // IE 8 serializes `undefined` as `"undefined"`. Safari <= 5.1.7 and
              // FF 3.1b3 pass this test.
              JSON3.stringify(undef) === undef &&
              // Safari <= 5.1.7 and FF 3.1b3 throw `Error`s and `TypeError`s,
              // respectively, if the value is omitted entirely.
              JSON3.stringify() === undef &&
              // FF 3.1b1, 2 throw an error if the given value is not a number,
              // string, array, object, Boolean, or `null` literal. This applies to
              // objects with custom `toJSON` methods as well, unless they are nested
              // inside object or array literals. YUI 3.0.0b1 ignores custom `toJSON`
              // methods entirely.
              JSON3.stringify(value) === "1" &&
              JSON3.stringify([value]) == "[1]" &&
              // Prototype <= 1.6.1 serializes `[undefined]` as `"[]"` instead of
              // `"[null]"`.
              JSON3.stringify([undef]) == "[null]" &&
              // YUI 3.0.0b1 fails to serialize `null` literals.
              JSON3.stringify(null) == "null" &&
              // FF 3.1b1, 2 halts serialization if an array contains a function:
              // `[1, true, getClass, 1]` serializes as "[1,true,],". These versions
              // of Firefox also allow trailing commas in JSON objects and arrays.
              // FF 3.1b3 elides non-JSON values from objects and arrays, unless they
              // define custom `toJSON` methods.
              JSON3.stringify([undef, getClass, null]) == "[null,null,null]" &&
              // Simple serialization test. FF 3.1b1 uses Unicode escape sequences
              // where character escape codes are expected (e.g., `\b` => `\u0008`).
              JSON3.stringify({ "A": [value, true, false, null, "\0\b\n\f\r\t"] }) == serialized &&
              // FF 3.1b1 and b2 ignore the `filter` and `width` arguments.
              JSON3.stringify(null, value) === "1" &&
              JSON3.stringify([1, 2], null, 1) == "[\n 1,\n 2\n]" &&
              // JSON 2, Prototype <= 1.7, and older WebKit builds incorrectly
              // serialize extended years.
              JSON3.stringify(new Date(-8.64e15)) == '"-271821-04-20T00:00:00.000Z"' &&
              // The milliseconds are optional in ES 5, but required in 5.1.
              JSON3.stringify(new Date(8.64e15)) == '"+275760-09-13T00:00:00.000Z"' &&
              // Firefox <= 11.0 incorrectly serializes years prior to 0 as negative
              // four-digit years instead of six-digit years. Credits: @Yaffle.
              JSON3.stringify(new Date(-621987552e5)) == '"-000001-01-01T00:00:00.000Z"' &&
              // Safari <= 5.1.5 and Opera >= 10.53 incorrectly serialize millisecond
              // values less than 1000. Credits: @Yaffle.
              JSON3.stringify(new Date(-1)) == '"1969-12-31T23:59:59.999Z"';
          } catch (exception) {
            stringifySupported = false;
          }
        }
        if (!all) {
          return stringifySupported;
        }
      }
      // Test `JSON.parse`.
      if (name == "json-parse" || all) {
        if (typeof JSON3.parse == "function") {
          try {
            // FF 3.1b1, b2 will throw an exception if a bare literal is provided.
            // Conforming implementations should also coerce the initial argument to
            // a string prior to parsing.
            if (JSON3.parse("0") === 0 && !JSON3.parse(false)) {
              // Simple parsing test.
              value = JSON3.parse(serialized);
              if ((parseSupported = value.A.length == 5 && value.A[0] == 1)) {
                try {
                  // Safari <= 5.1.2 and FF 3.1b1 allow unescaped tabs in strings.
                  parseSupported = !JSON3.parse('"\t"');
                } catch (exception) {}
                if (parseSupported) {
                  try {
                    // FF 4.0 and 4.0.1 allow leading `+` signs, and leading and
                    // trailing decimal points. FF 4.0, 4.0.1, and IE 9-10 also
                    // allow certain octal literals.
                    parseSupported = JSON3.parse("01") != 1;
                  } catch (exception) {}
                }
              }
            }
          } catch (exception) {
            parseSupported = false;
          }
        }
        if (!all) {
          return parseSupported;
        }
      }
      return stringifySupported && parseSupported;
    }
  }

  if (!has("json")) {
    // Define additional utility methods if the `Date` methods are buggy.
    if (!isExtended) {
      floor = Math.floor;
      // A mapping between the months of the year and the number of days between
      // January 1st and the first of the respective month.
      Months = [0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334];
      // Internal: Calculates the number of days between the Unix epoch and the
      // first day of the given month.
      getDay = function (year, month) {
        return Months[month] + 365 * (year - 1970) + floor((year - 1969 + (month = +(month > 1))) / 4) - floor((year - 1901 + month) / 100) + floor((year - 1601 + month) / 400);
      };
    }
    
    // Internal: Determines if a property is a direct property of the given
    // object. Delegates to the native `Object#hasOwnProperty` method.
    if (!(isProperty = {}.hasOwnProperty)) {
      isProperty = function (property) {
        var members = {}, constructor;
        if ((members.__proto__ = null, members.__proto__ = {
          // The *proto* property cannot be set multiple times in recent
          // versions of Firefox and SeaMonkey.
          "toString": 1
        }, members).toString != getClass) {
          // Safari <= 2.0.3 doesn't implement `Object#hasOwnProperty`, but
          // supports the mutable *proto* property.
          isProperty = function (property) {
            // Capture and break the object's prototype chain (see section 8.6.2
            // of the ES 5.1 spec). The parenthesized expression prevents an
            // unsafe transformation by the Closure Compiler.
            var original = this.__proto__, result = property in (this.__proto__ = null, this);
            // Restore the original prototype chain.
            this.__proto__ = original;
            return result;
          };
        } else {
          // Capture a reference to the top-level `Object` constructor.
          constructor = members.constructor;
          // Use the `constructor` property to simulate `Object#hasOwnProperty` in
          // other environments.
          isProperty = function (property) {
            var parent = (this.constructor || constructor).prototype;
            return property in this && !(property in parent && this[property] === parent[property]);
          };
        }
        members = null;
        return isProperty.call(this, property);
      };
    }

    // Internal: Normalizes the `for...in` iteration algorithm across
    // environments. Each enumerated key is yielded to a `callback` function.
    forEach = function (object, callback) {
      var size = 0, Properties, members, property, forEach;

      // Tests for bugs in the current environment's `for...in` algorithm. The
      // `valueOf` property inherits the non-enumerable flag from
      // `Object.prototype` in older versions of IE, Netscape, and Mozilla.
      (Properties = function () {
        this.valueOf = 0;
      }).prototype.valueOf = 0;

      // Iterate over a new instance of the `Properties` class.
      members = new Properties();
      for (property in members) {
        // Ignore all properties inherited from `Object.prototype`.
        if (isProperty.call(members, property)) {
          size++;
        }
      }
      Properties = members = null;

      // Normalize the iteration algorithm.
      if (!size) {
        // A list of non-enumerable properties inherited from `Object.prototype`.
        members = ["valueOf", "toString", "toLocaleString", "propertyIsEnumerable", "isPrototypeOf", "hasOwnProperty", "constructor"];
        // IE <= 8, Mozilla 1.0, and Netscape 6.2 ignore shadowed non-enumerable
        // properties.
        forEach = function (object, callback) {
          var isFunction = getClass.call(object) == "[object Function]", property, length;
          for (property in object) {
            // Gecko <= 1.0 enumerates the `prototype` property of functions under
            // certain conditions; IE does not.
            if (!(isFunction && property == "prototype") && isProperty.call(object, property)) {
              callback(property);
            }
          }
          // Manually invoke the callback for each non-enumerable property.
          for (length = members.length; property = members[--length]; isProperty.call(object, property) && callback(property));
        };
      } else if (size == 2) {
        // Safari <= 2.0.4 enumerates shadowed properties twice.
        forEach = function (object, callback) {
          // Create a set of iterated properties.
          var members = {}, isFunction = getClass.call(object) == "[object Function]", property;
          for (property in object) {
            // Store each property name to prevent double enumeration. The
            // `prototype` property of functions is not enumerated due to cross-
            // environment inconsistencies.
            if (!(isFunction && property == "prototype") && !isProperty.call(members, property) && (members[property] = 1) && isProperty.call(object, property)) {
              callback(property);
            }
          }
        };
      } else {
        // No bugs detected; use the standard `for...in` algorithm.
        forEach = function (object, callback) {
          var isFunction = getClass.call(object) == "[object Function]", property, isConstructor;
          for (property in object) {
            if (!(isFunction && property == "prototype") && isProperty.call(object, property) && !(isConstructor = property === "constructor")) {
              callback(property);
            }
          }
          // Manually invoke the callback for the `constructor` property due to
          // cross-environment inconsistencies.
          if (isConstructor || isProperty.call(object, (property = "constructor"))) {
            callback(property);
          }
        };
      }
      return forEach(object, callback);
    };

    // Public: Serializes a JavaScript `value` as a JSON string. The optional
    // `filter` argument may specify either a function that alters how object and
    // array members are serialized, or an array of strings and numbers that
    // indicates which properties should be serialized. The optional `width`
    // argument may be either a string or number that specifies the indentation
    // level of the output.
    if (!has("json-stringify")) {
      // Internal: A map of control characters and their escaped equivalents.
      Escapes = {
        "\\": "\\\\",
        '"': '\\"',
        "\b": "\\b",
        "\f": "\\f",
        "\n": "\\n",
        "\r": "\\r",
        "\t": "\\t"
      };

      // Internal: Converts `value` into a zero-padded string such that its
      // length is at least equal to `width`. The `width` must be <= 6.
      toPaddedString = function (width, value) {
        // The `|| 0` expression is necessary to work around a bug in
        // Opera <= 7.54u2 where `0 == -0`, but `String(-0) !== "0"`.
        return ("000000" + (value || 0)).slice(-width);
      };

      // Internal: Double-quotes a string `value`, replacing all ASCII control
      // characters (characters with code unit values between 0 and 31) with
      // their escaped equivalents. This is an implementation of the
      // `Quote(value)` operation defined in ES 5.1 section 15.12.3.
      quote = function (value) {
        var result = '"', index = 0, symbol;
        for (; symbol = value.charAt(index); index++) {
          // Escape the reverse solidus, double quote, backspace, form feed, line
          // feed, carriage return, and tab characters.
          result += '\\"\b\f\n\r\t'.indexOf(symbol) > -1 ? Escapes[symbol] :
            // If the character is a control character, append its Unicode escape
            // sequence; otherwise, append the character as-is.
            (Escapes[symbol] = symbol < " " ? "\\u00" + toPaddedString(2, symbol.charCodeAt(0).toString(16)) : symbol);
        }
        return result + '"';
      };

      // Internal: Recursively serializes an object. Implements the
      // `Str(key, holder)`, `JO(value)`, and `JA(value)` operations.
      serialize = function (property, object, callback, properties, whitespace, indentation, stack) {
        var value = object[property], className, year, month, date, time, hours, minutes, seconds, milliseconds, results, element, index, length, prefix, any, result;
        if (typeof value == "object" && value) {
          className = getClass.call(value);
          if (className == "[object Date]" && !isProperty.call(value, "toJSON")) {
            if (value > -1 / 0 && value < 1 / 0) {
              // Dates are serialized according to the `Date#toJSON` method
              // specified in ES 5.1 section 15.9.5.44. See section 15.9.1.15
              // for the ISO 8601 date time string format.
              if (getDay) {
                // Manually compute the year, month, date, hours, minutes,
                // seconds, and milliseconds if the `getUTC*` methods are
                // buggy. Adapted from @Yaffle's `date-shim` project.
                date = floor(value / 864e5);
                for (year = floor(date / 365.2425) + 1970 - 1; getDay(year + 1, 0) <= date; year++);
                for (month = floor((date - getDay(year, 0)) / 30.42); getDay(year, month + 1) <= date; month++);
                date = 1 + date - getDay(year, month);
                // The `time` value specifies the time within the day (see ES
                // 5.1 section 15.9.1.2). The formula `(A % B + B) % B` is used
                // to compute `A modulo B`, as the `%` operator does not
                // correspond to the `modulo` operation for negative numbers.
                time = (value % 864e5 + 864e5) % 864e5;
                // The hours, minutes, seconds, and milliseconds are obtained by
                // decomposing the time within the day. See section 15.9.1.10.
                hours = floor(time / 36e5) % 24;
                minutes = floor(time / 6e4) % 60;
                seconds = floor(time / 1e3) % 60;
                milliseconds = time % 1e3;
              } else {
                year = value.getUTCFullYear();
                month = value.getUTCMonth();
                date = value.getUTCDate();
                hours = value.getUTCHours();
                minutes = value.getUTCMinutes();
                seconds = value.getUTCSeconds();
                milliseconds = value.getUTCMilliseconds();
              }
              // Serialize extended years correctly.
              value = (year <= 0 || year >= 1e4 ? (year < 0 ? "-" : "+") + toPaddedString(6, year < 0 ? -year : year) : toPaddedString(4, year)) +
                "-" + toPaddedString(2, month + 1) + "-" + toPaddedString(2, date) +
                // Months, dates, hours, minutes, and seconds should have two
                // digits; milliseconds should have three.
                "T" + toPaddedString(2, hours) + ":" + toPaddedString(2, minutes) + ":" + toPaddedString(2, seconds) +
                // Milliseconds are optional in ES 5.0, but required in 5.1.
                "." + toPaddedString(3, milliseconds) + "Z";
            } else {
              value = null;
            }
          } else if (typeof value.toJSON == "function" && ((className != "[object Number]" && className != "[object String]" && className != "[object Array]") || isProperty.call(value, "toJSON"))) {
            // Prototype <= 1.6.1 adds non-standard `toJSON` methods to the
            // `Number`, `String`, `Date`, and `Array` prototypes. JSON 3
            // ignores all `toJSON` methods on these objects unless they are
            // defined directly on an instance.
            value = value.toJSON(property);
          }
        }
        if (callback) {
          // If a replacement function was provided, call it to obtain the value
          // for serialization.
          value = callback.call(object, property, value);
        }
        if (value === null) {
          return "null";
        }
        className = getClass.call(value);
        if (className == "[object Boolean]") {
          // Booleans are represented literally.
          return "" + value;
        } else if (className == "[object Number]") {
          // JSON numbers must be finite. `Infinity` and `NaN` are serialized as
          // `"null"`.
          return value > -1 / 0 && value < 1 / 0 ? "" + value : "null";
        } else if (className == "[object String]") {
          // Strings are double-quoted and escaped.
          return quote(value);
        }
        // Recursively serialize objects and arrays.
        if (typeof value == "object") {
          // Check for cyclic structures. This is a linear search; performance
          // is inversely proportional to the number of unique nested objects.
          for (length = stack.length; length--;) {
            if (stack[length] === value) {
              // Cyclic structures cannot be serialized by `JSON.stringify`.
              throw TypeError();
            }
          }
          // Add the object to the stack of traversed objects.
          stack.push(value);
          results = [];
          // Save the current indentation level and indent one additional level.
          prefix = indentation;
          indentation += whitespace;
          if (className == "[object Array]") {
            // Recursively serialize array elements.
            for (index = 0, length = value.length; index < length; any || (any = true), index++) {
              element = serialize(index, value, callback, properties, whitespace, indentation, stack);
              results.push(element === undef ? "null" : element);
            }
            result = any ? (whitespace ? "[\n" + indentation + results.join(",\n" + indentation) + "\n" + prefix + "]" : ("[" + results.join(",") + "]")) : "[]";
          } else {
            // Recursively serialize object members. Members are selected from
            // either a user-specified list of property names, or the object
            // itself.
            forEach(properties || value, function (property) {
              var element = serialize(property, value, callback, properties, whitespace, indentation, stack);
              if (element !== undef) {
                // According to ES 5.1 section 15.12.3: "If `gap` {whitespace}
                // is not the empty string, let `member` {quote(property) + ":"}
                // be the concatenation of `member` and the `space` character."
                // The "`space` character" refers to the literal space
                // character, not the `space` {width} argument provided to
                // `JSON.stringify`.
                results.push(quote(property) + ":" + (whitespace ? " " : "") + element);
              }
              any || (any = true);
            });
            result = any ? (whitespace ? "{\n" + indentation + results.join(",\n" + indentation) + "\n" + prefix + "}" : ("{" + results.join(",") + "}")) : "{}";
          }
          // Remove the object from the traversed object stack.
          stack.pop();
          return result;
        }
      };

      // Public: `JSON.stringify`. See ES 5.1 section 15.12.3.
      JSON3.stringify = function (source, filter, width) {
        var whitespace, callback, properties, index, length, value;
        if (typeof filter == "function" || typeof filter == "object" && filter) {
          if (getClass.call(filter) == "[object Function]") {
            callback = filter;
          } else if (getClass.call(filter) == "[object Array]") {
            // Convert the property names array into a makeshift set.
            properties = {};
            for (index = 0, length = filter.length; index < length; value = filter[index++], ((getClass.call(value) == "[object String]" || getClass.call(value) == "[object Number]") && (properties[value] = 1)));
          }
        }
        if (width) {
          if (getClass.call(width) == "[object Number]") {
            // Convert the `width` to an integer and create a string containing
            // `width` number of space characters.
            if ((width -= width % 1) > 0) {
              for (whitespace = "", width > 10 && (width = 10); whitespace.length < width; whitespace += " ");
            }
          } else if (getClass.call(width) == "[object String]") {
            whitespace = width.length <= 10 ? width : width.slice(0, 10);
          }
        }
        // Opera <= 7.54u2 discards the values associated with empty string keys
        // (`""`) only if they are used directly within an object member list
        // (e.g., `!("" in { "": 1})`).
        return serialize("", (value = {}, value[""] = source, value), callback, properties, whitespace, "", []);
      };
    }

    // Public: Parses a JSON source string.
    if (!has("json-parse")) {
      fromCharCode = String.fromCharCode;
      // Internal: A map of escaped control characters and their unescaped
      // equivalents.
      Unescapes = {
        "\\": "\\",
        '"': '"',
        "/": "/",
        "b": "\b",
        "t": "\t",
        "n": "\n",
        "f": "\f",
        "r": "\r"
      };

      // Internal: Resets the parser state and throws a `SyntaxError`.
      abort = function() {
        Index = Source = null;
        throw SyntaxError();
      };

      // Internal: Returns the next token, or `"$"` if the parser has reached
      // the end of the source string. A token may be a string, number, `null`
      // literal, or Boolean literal.
      lex = function () {
        var source = Source, length = source.length, symbol, value, begin, position, sign;
        while (Index < length) {
          symbol = source.charAt(Index);
          if ("\t\r\n ".indexOf(symbol) > -1) {
            // Skip whitespace tokens, including tabs, carriage returns, line
            // feeds, and space characters.
            Index++;
          } else if ("{}[]:,".indexOf(symbol) > -1) {
            // Parse a punctuator token at the current position.
            Index++;
            return symbol;
          } else if (symbol == '"') {
            // Advance to the next character and parse a JSON string at the
            // current position. String tokens are prefixed with the sentinel
            // `@` character to distinguish them from punctuators.
            for (value = "@", Index++; Index < length;) {
              symbol = source.charAt(Index);
              if (symbol < " ") {
                // Unescaped ASCII control characters are not permitted.
                abort();
              } else if (symbol == "\\") {
                // Parse escaped JSON control characters, `"`, `\`, `/`, and
                // Unicode escape sequences.
                symbol = source.charAt(++Index);
                if ('\\"/btnfr'.indexOf(symbol) > -1) {
                  // Revive escaped control characters.
                  value += Unescapes[symbol];
                  Index++;
                } else if (symbol == "u") {
                  // Advance to the first character of the escape sequence.
                  begin = ++Index;
                  // Validate the Unicode escape sequence.
                  for (position = Index + 4; Index < position; Index++) {
                    symbol = source.charAt(Index);
                    // A valid sequence comprises four hexdigits that form a
                    // single hexadecimal value.
                    if (!(symbol >= "0" && symbol <= "9" || symbol >= "a" && symbol <= "f" || symbol >= "A" && symbol <= "F")) {
                      // Invalid Unicode escape sequence.
                      abort();
                    }
                  }
                  // Revive the escaped character.
                  value += fromCharCode("0x" + source.slice(begin, Index));
                } else {
                  // Invalid escape sequence.
                  abort();
                }
              } else {
                if (symbol == '"') {
                  // An unescaped double-quote character marks the end of the
                  // string.
                  break;
                }
                // Append the original character as-is.
                value += symbol;
                Index++;
              }
            }
            if (source.charAt(Index) == '"') {
              Index++;
              // Return the revived string.
              return value;
            }
            // Unterminated string.
            abort();
          } else {
            // Parse numbers and literals.
            begin = Index;
            // Advance the scanner's position past the sign, if one is
            // specified.
            if (symbol == "-") {
              sign = true;
              symbol = source.charAt(++Index);
            }
            // Parse an integer or floating-point value.
            if (symbol >= "0" && symbol <= "9") {
              // Leading zeroes are interpreted as octal literals.
              if (symbol == "0" && (symbol = source.charAt(Index + 1), symbol >= "0" && symbol <= "9")) {
                // Illegal octal literal.
                abort();
              }
              sign = false;
              // Parse the integer component.
              for (; Index < length && (symbol = source.charAt(Index), symbol >= "0" && symbol <= "9"); Index++);
              // Floats cannot contain a leading decimal point; however, this
              // case is already accounted for by the parser.
              if (source.charAt(Index) == ".") {
                position = ++Index;
                // Parse the decimal component.
                for (; position < length && (symbol = source.charAt(position), symbol >= "0" && symbol <= "9"); position++);
                if (position == Index) {
                  // Illegal trailing decimal.
                  abort();
                }
                Index = position;
              }
              // Parse exponents.
              symbol = source.charAt(Index);
              if (symbol == "e" || symbol == "E") {
                // Skip past the sign following the exponent, if one is
                // specified.
                symbol = source.charAt(++Index);
                if (symbol == "+" || symbol == "-") {
                  Index++;
                }
                // Parse the exponential component.
                for (position = Index; position < length && (symbol = source.charAt(position), symbol >= "0" && symbol <= "9"); position++);
                if (position == Index) {
                  // Illegal empty exponent.
                  abort();
                }
                Index = position;
              }
              // Coerce the parsed value to a JavaScript number.
              return +source.slice(begin, Index);
            }
            // A negative sign may only precede numbers.
            if (sign) {
              abort();
            }
            // `true`, `false`, and `null` literals.
            if (source.slice(Index, Index + 4) == "true") {
              Index += 4;
              return true;
            } else if (source.slice(Index, Index + 5) == "false") {
              Index += 5;
              return false;
            } else if (source.slice(Index, Index + 4) == "null") {
              Index += 4;
              return null;
            }
            // Unrecognized token.
            abort();
          }
        }
        // Return the sentinel `$` character if the parser has reached the end
        // of the source string.
        return "$";
      };

      // Internal: Parses a JSON `value` token.
      get = function (value) {
        var results, any, key;
        if (value == "$") {
          // Unexpected end of input.
          abort();
        }
        if (typeof value == "string") {
          if (value.charAt(0) == "@") {
            // Remove the sentinel `@` character.
            return value.slice(1);
          }
          // Parse object and array literals.
          if (value == "[") {
            // Parses a JSON array, returning a new JavaScript array.
            results = [];
            for (;; any || (any = true)) {
              value = lex();
              // A closing square bracket marks the end of the array literal.
              if (value == "]") {
                break;
              }
              // If the array literal contains elements, the current token
              // should be a comma separating the previous element from the
              // next.
              if (any) {
                if (value == ",") {
                  value = lex();
                  if (value == "]") {
                    // Unexpected trailing `,` in array literal.
                    abort();
                  }
                } else {
                  // A `,` must separate each array element.
                  abort();
                }
              }
              // Elisions and leading commas are not permitted.
              if (value == ",") {
                abort();
              }
              results.push(get(value));
            }
            return results;
          } else if (value == "{") {
            // Parses a JSON object, returning a new JavaScript object.
            results = {};
            for (;; any || (any = true)) {
              value = lex();
              // A closing curly brace marks the end of the object literal.
              if (value == "}") {
                break;
              }
              // If the object literal contains members, the current token
              // should be a comma separator.
              if (any) {
                if (value == ",") {
                  value = lex();
                  if (value == "}") {
                    // Unexpected trailing `,` in object literal.
                    abort();
                  }
                } else {
                  // A `,` must separate each object member.
                  abort();
                }
              }
              // Leading commas are not permitted, object property names must be
              // double-quoted strings, and a `:` must separate each property
              // name and value.
              if (value == "," || typeof value != "string" || value.charAt(0) != "@" || lex() != ":") {
                abort();
              }
              results[value.slice(1)] = get(lex());
            }
            return results;
          }
          // Unexpected token encountered.
          abort();
        }
        return value;
      };

      // Internal: Updates a traversed object member.
      update = function(source, property, callback) {
        var element = walk(source, property, callback);
        if (element === undef) {
          delete source[property];
        } else {
          source[property] = element;
        }
      };

      // Internal: Recursively traverses a parsed JSON object, invoking the
      // `callback` function for each value. This is an implementation of the
      // `Walk(holder, name)` operation defined in ES 5.1 section 15.12.2.
      walk = function (source, property, callback) {
        var value = source[property], length;
        if (typeof value == "object" && value) {
          if (getClass.call(value) == "[object Array]") {
            for (length = value.length; length--;) {
              update(value, length, callback);
            }
          } else {
            // `forEach` can't be used to traverse an array in Opera <= 8.54,
            // as `Object#hasOwnProperty` returns `false` for array indices
            // (e.g., `![1, 2, 3].hasOwnProperty("0")`).
            forEach(value, function (property) {
              update(value, property, callback);
            });
          }
        }
        return callback.call(source, property, value);
      };

      // Public: `JSON.parse`. See ES 5.1 section 15.12.2.
      JSON3.parse = function (source, callback) {
        var result, value;
        Index = 0;
        Source = source;
        result = get(lex());
        // If a JSON string contains multiple tokens, it is invalid.
        if (lex() != "$") {
          abort();
        }
        // Reset the parser state.
        Index = Source = null;
        return callback && getClass.call(callback) == "[object Function]" ? walk((value = {}, value[""] = result, value), "", callback) : result;
      };
    }
  }

  // Export for asynchronous module loaders.
  if (isLoader) {
    define(function () {
      return JSON3;
    });
  }
}).call(this);