System.Reflection.Binder.Default.check_type_with_score C# (CSharp) Method

			static int check_type_with_score (Type from, Type to)
			{
				if (from == null)
					return to.IsValueType ? -1 : 0;

				if (from == to)
					return 0;

				if (to == typeof (object))
					return 4;

				TypeCode fromt = Type.GetTypeCode (from);
				TypeCode tot = Type.GetTypeCode (to);

				switch (fromt) {
				case TypeCode.Char:
					switch (tot) {
					case TypeCode.UInt16:
						return 0;

					case TypeCode.UInt32:
					case TypeCode.Int32:
					case TypeCode.UInt64:
					case TypeCode.Int64:
					case TypeCode.Single:
					case TypeCode.Double:
						return 2;
					}
					return -1;
				case TypeCode.Byte:
					switch (tot) {
					case TypeCode.Char:
					case TypeCode.UInt16:
					case TypeCode.Int16:
					case TypeCode.UInt32:
					case TypeCode.Int32:
					case TypeCode.UInt64:
					case TypeCode.Int64:
					case TypeCode.Single:
					case TypeCode.Double:
						return 2;
					}
					return (from.IsEnum && to == typeof (Enum)) ? 1 : -1;
				case TypeCode.SByte:
					switch (tot) {
					case TypeCode.Int16:
					case TypeCode.Int32:
					case TypeCode.Int64:
					case TypeCode.Single:
					case TypeCode.Double:
						return 2;
					}
					return (from.IsEnum && to == typeof (Enum)) ? 1 : -1;
				case TypeCode.UInt16:
					switch (tot) {
					case TypeCode.UInt32:
					case TypeCode.Int32:
					case TypeCode.UInt64:
					case TypeCode.Int64:
					case TypeCode.Single:
					case TypeCode.Double:
						return 2;
					}
					return (from.IsEnum && to == typeof (Enum)) ? 1 : -1;
				case TypeCode.Int16:
					switch (tot) {
					case TypeCode.Int32:
					case TypeCode.Int64:
					case TypeCode.Single:
					case TypeCode.Double:
						return 2;
					}
					return (from.IsEnum && to == typeof (Enum)) ? 1 : -1;
				case TypeCode.UInt32:
					switch (tot) {
					case TypeCode.UInt64:
					case TypeCode.Int64:
					case TypeCode.Single:
					case TypeCode.Double:
						return 2;
					}
					return (from.IsEnum && to == typeof (Enum)) ? 1 : -1;
				case TypeCode.Int32:
					switch (tot) {
					case TypeCode.Int64:
					case TypeCode.Single:
					case TypeCode.Double:
						return 2;
					}
					return (from.IsEnum && to == typeof (Enum)) ? 1 : -1;
				case TypeCode.UInt64:
				case TypeCode.Int64:
					switch (tot) {
					case TypeCode.Single:
					case TypeCode.Double:
						return 2;
					}
					return (from.IsEnum && to == typeof (Enum)) ? 1 : -1;
				case TypeCode.Single:
					return tot == TypeCode.Double ? 2 : -1;
				default:
					return (to.IsAssignableFrom (from)) ? 3 : -1;
				}
			}
		}