Beispiel #1
0
        /// <summary>
        /// Attempt to parse a string into a JSONObject.
        /// </summary>
        /// <param name="jsonString"></param>
        /// <returns>A new JSONObject or null if parsing fails.</returns>
        public static JSONObject Parse(string jsonString)
        {
            if (string.IsNullOrEmpty(jsonString))
            {
                return(null);
            }

            JSONValue currentValue = null;

            var keyList = new List <string>();

            var state = JSONParsingState.Object;

            for (var startPosition = 0; startPosition < jsonString.Length; ++startPosition)
            {
                startPosition = SkipWhitespace(jsonString, startPosition);

                switch (state)
                {
                case JSONParsingState.Object:
                    if (jsonString[startPosition] != '{')
                    {
                        return(Fail('{', startPosition));
                    }

                    JSONValue newObj = new JSONObject();
                    if (currentValue != null)
                    {
                        newObj.Parent = currentValue;
                    }
                    currentValue = newObj;

                    state = JSONParsingState.Key;
                    break;

                case JSONParsingState.EndObject:
                    if (jsonString[startPosition] != '}')
                    {
                        return(Fail('}', startPosition));
                    }

                    if (currentValue.Parent == null)
                    {
                        return(currentValue.Obj);
                    }

                    switch (currentValue.Parent.Type)
                    {
                    case JSONValueType.Object:
                        currentValue.Parent.Obj.values[keyList.Pop()] = new JSONValue(currentValue.Obj);
                        break;

                    case JSONValueType.Array:
                        currentValue.Parent.Array.Add(new JSONValue(currentValue.Obj));
                        break;

                    default:
                        return(Fail("valid object", startPosition));
                    }
                    currentValue = currentValue.Parent;

                    state = JSONParsingState.ValueSeparator;
                    break;

                case JSONParsingState.Key:
                    if (jsonString[startPosition] == '}')
                    {
                        --startPosition;
                        state = JSONParsingState.EndObject;
                        break;
                    }

                    var key = ParseString(jsonString, ref startPosition);
                    if (key == null)
                    {
                        return(Fail("key string", startPosition));
                    }
                    keyList.Add(key);
                    state = JSONParsingState.KeyValueSeparator;
                    break;

                case JSONParsingState.KeyValueSeparator:
                    if (jsonString[startPosition] != ':')
                    {
                        return(Fail(':', startPosition));
                    }
                    state = JSONParsingState.Value;
                    break;

                case JSONParsingState.ValueSeparator:
                    switch (jsonString[startPosition])
                    {
                    case ',':
                        state = currentValue.Type == JSONValueType.Object ? JSONParsingState.Key : JSONParsingState.Value;
                        break;

                    case '}':
                        state = JSONParsingState.EndObject;
                        --startPosition;
                        break;

                    case ']':
                        state = JSONParsingState.EndArray;
                        --startPosition;
                        break;

                    default:
                        return(Fail(", } ]", startPosition));
                    }
                    break;

                case JSONParsingState.Value: {
                    var c = jsonString[startPosition];
                    if (c == '"')
                    {
                        state = JSONParsingState.String;
                    }
                    else if (char.IsDigit(c) || c == '-')
                    {
                        state = JSONParsingState.Number;
                    }
                    else
                    {
                        switch (c)
                        {
                        case '{':
                            state = JSONParsingState.Object;
                            break;

                        case '[':
                            state = JSONParsingState.Array;
                            break;

                        case ']':
                            if (currentValue.Type == JSONValueType.Array)
                            {
                                state = JSONParsingState.EndArray;
                            }
                            else
                            {
                                return(Fail("valid array", startPosition));
                            }
                            break;

                        case 'f':
                        case 't':
                            state = JSONParsingState.Boolean;
                            break;


                        case 'n':
                            state = JSONParsingState.Null;
                            break;

                        default:
                            return(Fail("beginning of value", startPosition));
                        }
                    }

                    --startPosition;                             //To re-evaluate this char in the newly selected state
                    break;
                }

                case JSONParsingState.String:
                    var str = ParseString(jsonString, ref startPosition);
                    if (str == null)
                    {
                        return(Fail("string value", startPosition));
                    }

                    switch (currentValue.Type)
                    {
                    case JSONValueType.Object:
                        currentValue.Obj.values[keyList.Pop()] = new JSONValue(str);
                        break;

                    case JSONValueType.Array:
                        currentValue.Array.Add(str);
                        break;

                    default:
                        JSONLogger.Error("Fatal error, current JSON value not valid");
                        return(null);
                    }

                    state = JSONParsingState.ValueSeparator;
                    break;

                case JSONParsingState.Number:
                    var number = ParseNumber(jsonString, ref startPosition);
                    if (double.IsNaN(number))
                    {
                        return(Fail("valid number", startPosition));
                    }

                    switch (currentValue.Type)
                    {
                    case JSONValueType.Object:
                        currentValue.Obj.values[keyList.Pop()] = new JSONValue(number);
                        break;

                    case JSONValueType.Array:
                        currentValue.Array.Add(number);
                        break;

                    default:
                        JSONLogger.Error("Fatal error, current JSON value not valid");
                        return(null);
                    }

                    state = JSONParsingState.ValueSeparator;

                    break;

                case JSONParsingState.Boolean:
                    if (jsonString[startPosition] == 't')
                    {
                        if (jsonString.Length < startPosition + 4 ||
                            jsonString[startPosition + 1] != 'r' ||
                            jsonString[startPosition + 2] != 'u' ||
                            jsonString[startPosition + 3] != 'e')
                        {
                            return(Fail("true", startPosition));
                        }

                        switch (currentValue.Type)
                        {
                        case JSONValueType.Object:
                            currentValue.Obj.values[keyList.Pop()] = new JSONValue(true);
                            break;

                        case JSONValueType.Array:
                            currentValue.Array.Add(new JSONValue(true));
                            break;

                        default:
                            JSONLogger.Error("Fatal error, current JSON value not valid");
                            return(null);
                        }

                        startPosition += 3;
                    }
                    else
                    {
                        if (jsonString.Length < startPosition + 5 ||
                            jsonString[startPosition + 1] != 'a' ||
                            jsonString[startPosition + 2] != 'l' ||
                            jsonString[startPosition + 3] != 's' ||
                            jsonString[startPosition + 4] != 'e')
                        {
                            return(Fail("false", startPosition));
                        }

                        switch (currentValue.Type)
                        {
                        case JSONValueType.Object:
                            currentValue.Obj.values[keyList.Pop()] = new JSONValue(false);
                            break;

                        case JSONValueType.Array:
                            currentValue.Array.Add(new JSONValue(false));
                            break;

                        default:
                            JSONLogger.Error("Fatal error, current JSON value not valid");
                            return(null);
                        }

                        startPosition += 4;
                    }

                    state = JSONParsingState.ValueSeparator;
                    break;

                case JSONParsingState.Array:
                    if (jsonString[startPosition] != '[')
                    {
                        return(Fail('[', startPosition));
                    }

                    JSONValue newArray = new JSONArray();
                    if (currentValue != null)
                    {
                        newArray.Parent = currentValue;
                    }
                    currentValue = newArray;

                    state = JSONParsingState.Value;
                    break;

                case JSONParsingState.EndArray:
                    if (jsonString[startPosition] != ']')
                    {
                        return(Fail(']', startPosition));
                    }

                    if (currentValue.Parent == null)
                    {
                        return(currentValue.Obj);
                    }

                    switch (currentValue.Parent.Type)
                    {
                    case JSONValueType.Object:
                        currentValue.Parent.Obj.values[keyList.Pop()] = new JSONValue(currentValue.Array);
                        break;

                    case JSONValueType.Array:
                        currentValue.Parent.Array.Add(new JSONValue(currentValue.Array));
                        break;

                    default:
                        return(Fail("valid object", startPosition));
                    }
                    currentValue = currentValue.Parent;

                    state = JSONParsingState.ValueSeparator;
                    break;

                case JSONParsingState.Null:
                    if (jsonString[startPosition] == 'n')
                    {
                        if (jsonString.Length < startPosition + 4 ||
                            jsonString[startPosition + 1] != 'u' ||
                            jsonString[startPosition + 2] != 'l' ||
                            jsonString[startPosition + 3] != 'l')
                        {
                            return(Fail("null", startPosition));
                        }

                        switch (currentValue.Type)
                        {
                        case JSONValueType.Object:
                            currentValue.Obj.values[keyList.Pop()] = new JSONValue(JSONValueType.Null);
                            break;

                        case JSONValueType.Array:
                            currentValue.Array.Add(new JSONValue(JSONValueType.Null));
                            break;

                        default:
                            JSONLogger.Error("Fatal error, current JSON value not valid");
                            return(null);
                        }

                        startPosition += 3;
                    }
                    state = JSONParsingState.ValueSeparator;
                    break;
                }
            }
            JSONLogger.Error("Unexpected end of string");
            return(null);
        }
Beispiel #2
0
 static JSONObject Fail(string expected, int position)
 {
     JSONLogger.Error("Invalid json string, expecting " + expected + " at " + position);
     return(null);
 }