function calculateType()
    {
        if ($this->data === true || $this->data === false) {
            return 'boolean';
        }
        if (is_integer($this->data)) {
            return 'int';
        }
        if (is_double($this->data)) {
            return 'double';
        }

        // Deal with IXR object types base64 and date
        if (is_object($this->data) && is_a($this->data, 'IXR_Date')) {
            return 'date';
        }
        if (is_object($this->data) && is_a($this->data, 'IXR_Base64')) {
            return 'base64';
        }

        // If it is a normal PHP object convert it in to a struct
        if (is_object($this->data)) {
            $this->data = get_object_vars($this->data);
            return 'struct';
        }
        if (!is_array($this->data)) {
            return 'string';
        }

        // We have an array - is it an array or a struct?
        if ($this->isStruct($this->data)) {
            return 'struct';
        } else {
            return 'array';
        }
    }