internal static object ParseValue()

in src/StructuredLogger/Strings/JsonParser.cs [132:260]
121 lines of code
36 McCabe index (conditional complexity)

        internal static object ParseValue(Type type, string json)
        {
            if (type == typeof(string))
            {
                if (json.Length <= 2)
                    return string.Empty;
                StringBuilder parseStringBuilder = new StringBuilder(json.Length);
                for (int i = 1; i < json.Length - 1; ++i)
                {
                    if (json[i] == '\\' && i + 1 < json.Length - 1)
                    {
                        int j = "\"\\nrtbf/".IndexOf(json[i + 1]);
                        if (j >= 0)
                        {
                            parseStringBuilder.Append("\"\\\n\r\t\b\f/"[j]);
                            ++i;
                            continue;
                        }
                        if (json[i + 1] == 'u' && i + 5 < json.Length - 1)
                        {
                            UInt32 c = 0;
                            if (UInt32.TryParse(json.Substring(i + 2, 4), System.Globalization.NumberStyles.AllowHexSpecifier, null, out c))
                            {
                                parseStringBuilder.Append((char)c);
                                i += 5;
                                continue;
                            }
                        }
                    }
                    parseStringBuilder.Append(json[i]);
                }
                return parseStringBuilder.ToString();
            }
            if (type.IsPrimitive)
            {
                var result = Convert.ChangeType(json, type, System.Globalization.CultureInfo.InvariantCulture);
                return result;
            }
            if (type == typeof(decimal))
            {
                decimal result;
                decimal.TryParse(json, System.Globalization.NumberStyles.Float, System.Globalization.CultureInfo.InvariantCulture, out result);
                return result;
            }
            if (json == "null")
            {
                return null;
            }
            if (type.IsEnum)
            {
                if (json[0] == '"')
                    json = json.Substring(1, json.Length - 2);
                try
                {
                    return Enum.Parse(type, json, false);
                }
                catch
                {
                    return 0;
                }
            }
            if (type.IsArray)
            {
                Type arrayType = type.GetElementType();
                if (json[0] != '[' || json[json.Length - 1] != ']')
                    return null;

                List<string> elems = Split(json);
                Array newArray = Array.CreateInstance(arrayType, elems.Count);
                for (int i = 0; i < elems.Count; i++)
                    newArray.SetValue(ParseValue(arrayType, elems[i]), i);
                splitArrayPool.Push(elems);
                return newArray;
            }
            if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(List<>))
            {
                Type listType = type.GetGenericArguments()[0];
                if (json[0] != '[' || json[json.Length - 1] != ']')
                    return null;

                List<string> elems = Split(json);
                var list = (IList)type.GetConstructor(new Type[] { typeof(int) }).Invoke(new object[] { elems.Count });
                for (int i = 0; i < elems.Count; i++)
                    list.Add(ParseValue(listType, elems[i]));
                splitArrayPool.Push(elems);
                return list;
            }
            if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(Dictionary<,>))
            {
                Type keyType, valueType;
                {
                    Type[] args = type.GetGenericArguments();
                    keyType = args[0];
                    valueType = args[1];
                }

                //Refuse to parse dictionary keys that aren't of type string
                if (keyType != typeof(string))
                    return null;
                //Must be a valid dictionary element
                if (json[0] != '{' || json[json.Length - 1] != '}')
                    return null;
                //The list is split into key/value pairs only, this means the split must be divisible by 2 to be valid JSON
                List<string> elems = Split(json);
                if (elems.Count % 2 != 0)
                    return null;

                var dictionary = (IDictionary)type.GetConstructor(new Type[] { typeof(int) }).Invoke(new object[] { elems.Count / 2 });
                for (int i = 0; i < elems.Count; i += 2)
                {
                    if (elems[i].Length <= 2)
                        continue;
                    string keyValue = elems[i].Substring(1, elems[i].Length - 2);
                    object val = ParseValue(valueType, elems[i + 1]);
                    dictionary[keyValue] = val;
                }
                return dictionary;
            }
            if (type == typeof(object))
            {
                return ParseAnonymousValue(json);
            }
            if (json[0] == '{' && json[json.Length - 1] == '}')
            {
                return ParseObject(type, json);
            }

            return null;
        }