My Dynamic JSON object converter

gistfile1.cs

sealed class DynamicJsonConverter : JavaScriptConverter
		{
			public override object Deserialize(IDictionary<string, object> dictionary, Type type, JavaScriptSerializer serializer)
			{
				if (dictionary == null)
					throw new ArgumentNullException("dictionary");

				return type == typeof(object) ? new DynamicJsonObject(dictionary) : null;
			}

			public override IDictionary<string, object> Serialize(object obj, JavaScriptSerializer serializer)
			{
				throw new NotImplementedException();
			}

			public override IEnumerable<Type> SupportedTypes
			{
				get { return new ReadOnlyCollection<Type>(new List<Type>(new[] { typeof(object) })); }
			}

			private sealed class DynamicJsonObject : DynamicObject
			{
				private readonly IDictionary<string, object> _dictionary;

				public DynamicJsonObject(IDictionary<string, object> dictionary)
				{
					if (dictionary == null)
						throw new ArgumentNullException("dictionary");
					_dictionary = dictionary;
				}

				public override string ToString()
				{
					var sb = new StringBuilder("{");
					ToString(sb);
					return sb.ToString();
				}

				private void ToString(StringBuilder sb)
				{
					var firstInDictionary = true;
					foreach (var pair in _dictionary)
					{
						if (!firstInDictionary)
							sb.Append(",");
						firstInDictionary = false;
						var value = pair.Value;
						var name = pair.Key;
						if (value is string)
						{
							sb.AppendFormat("{0}:\"{1}\"", name, value);
						}
						else if (value is IDictionary<string, object>)
						{
							new DynamicJsonObject((IDictionary<string, object>)value).ToString(sb);
						}
						else if (value is ArrayList)
						{
							sb.Append(name + ":[");
							var firstInArray = true;
							foreach (var arrayValue in (ArrayList)value)
							{
								if (!firstInArray)
									sb.Append(",");
								firstInArray = false;
								if (arrayValue is IDictionary<string, object>)
									new DynamicJsonObject((IDictionary<string, object>)arrayValue).ToString(sb);
								else if (arrayValue is string)
									sb.AppendFormat("\"{0}\"", arrayValue);
								else
									sb.AppendFormat("{0}", arrayValue);

							}
							sb.Append("]");
						}
						else
						{
							sb.AppendFormat("{0}:{1}", name, value);
						}
					}
					sb.Append("}");
				}

				public override bool TryGetMember(GetMemberBinder binder, out object result)
				{
					if (!_dictionary.TryGetValue(binder.Name, out result))
					{
						// return null to avoid exception.  caller can check for null this way...
						result = null;
						return true;
					}

					var dictionary = result as IDictionary<string, object>;
					if (dictionary != null)
					{
						result = new DynamicJsonObject(dictionary);
						return true;
					}

					var arrayList = result as ArrayList;
					if (arrayList != null && arrayList.Count > 0)
					{
						if (arrayList[0] is IDictionary<string, object>)
							result = new List<object>(arrayList.Cast<IDictionary<string, object>>().Select(x => new DynamicJsonObject(x)));
						else
							result = new List<object>(arrayList.Cast<object>());
					}
					return true;
				}
			}
		}