Own realization SAX parser of JSON

JSON2.js

// Generated by CoffeeScript 1.4.0
(function() {
  var DATA, JSON2, res;

  JSON2 = {
    OBJECT: "Object",
    ARRAY: "Array",
    nextToken: function(buf, i) {
      var ch, isFloat, isNum, isWord, str, token;
      token = void 0;
      isWord = false;
      isNum = false;
      isFloat = false;
      str = "";
      while (i < buf.length) {
        ch = buf.charCodeAt(i);
        ++i;
        switch (ch) {
          case 123:
          case 125:
          case 58:
          case 91:
          case 93:
          case 44:
            return [String.fromCharCode(ch), str, i];
          case 34:
            isWord = !isWord;
            if (!isWord) {
              return ["w", str, i];
            }
            break;
          default:
            if (ch === 46 && isNum) {
              if (!isFloat) {
                isFloat = true;
              } else {
                throw new Error("more then one char '.' in number token");
              }
            }
            if (!isWord && ch >= 48 && ch <= 57) {
              isNum = true;
            }
            if (isWord || isNum) {
              str += String.fromCharCode(ch);
            }
            if (isNum && i + 1 < buf.length) {
              ch = buf.charCodeAt(i + 1);
              if ((ch < 48 || ch > 57) && ch !== 46) {
                if (!isFloat) {
                  return ['i', parseInt(str), i];
                } else {
                  return ["f", parseFloat(str), i];
                }
              }
            }
        }
      }
      return ["", "", i];
    },
    processValue: function(obj, key, value, type) {
      if (type === this.OBJECT) {
        if ((key != null) && (value != null) && (obj != null)) {
          obj[key] = value;
        } else {
          throw new Error("Invalid params for [" + type + "]: key:'" + key + "' value:'" + value + "' obj:'" + obj + "'");
        }
      } else if (type === this.ARRAY) {
        if ((value != null) && (obj != null)) {
          obj.push(value);
        } else {
          throw new Error("Invalid params for [" + type + "]: value:'" + value + "' obj:'" + obj + "'");
        }
      } else {
        throw new Error("Unknown type");
      }
      key = null;
      value = null;
      return [obj, key, value, type];
    },
    _parse: function(buf, obj, i, type) {
      var key, token, v, value, _ref, _ref1, _ref2, _ref3, _ref4;
      key = null;
      value = null;
      try {
        while (i < buf.length) {
          _ref = this.nextToken(buf, i), token = _ref[0], v = _ref[1], i = _ref[2];
          switch (token) {
            case "{":
              _ref1 = this._parse(buf, {}, i, this.OBJECT), i = _ref1[0], value = _ref1[1];
              break;
            case "[":
              _ref2 = this._parse(buf, [], i, this.ARRAY), i = _ref2[0], value = _ref2[1];
              break;
            case "}":
            case "]":
              _ref3 = this.processValue(obj, key, value, type), obj = _ref3[0], key = _ref3[1], value = _ref3[2], type = _ref3[3];
              return [i, obj];
            case ",":
              _ref4 = this.processValue(obj, key, value, type), obj = _ref4[0], key = _ref4[1], value = _ref4[2], type = _ref4[3];
              break;
            case ":":
              key = value;
              value = null;
              break;
            case "w":
            case "i":
            case "f":
              value = v;
          }
        }
      } catch (e) {
        e.buf = buf;
        e.i = i;
        throw e;
      }
      return [i, value];
    },
    parse: function(buf) {
      try {
        return this._parse(buf, {}, 0, this.OBJECT)[1];
      } catch (e) {
        throw new Error("msg:" + e.message + " text:" + (e.buf.slice(0, e.i).to));
      }
    }
  };

  DATA = "{\n  \"one\":[0,\"1\",0,\"3\",\"4\",\"9\"],\n  \"two\":\"three\",\n  \"four\":{\n    1:\"one\",\n    \"five\":1.0,\n    \"six\":3\n  }\n}";

  res = JSON2.parse(DATA.toString());

  if (res.one.length === 6) {
    console.log("PASS");
  } else {
    console.error("FAIL");
  }

  if (res.one[0] === 0) {
    console.log("PASS");
  } else {
    console.error("FAIL");
  }

  if (res.one[1] === "1") {
    console.log("PASS");
  } else {
    console.error("FAIL");
  }

  if (res.two === "three") {
    console.log("PASS");
  } else {
    console.error("FAIL");
  }

  if (res.four["1"] === "one") {
    console.log("PASS");
  } else {
    console.error("FAIL");
  }

}).call(this);