60   public:

    60   public:

    61     static const char * to_string(symbol_c *symbol) {

    61     static const char * to_string(symbol_c *symbol) {

    62       if (NULL == singleton)    singleton = new elementary_type_c;

    62       if (NULL == singleton)    singleton = new elementary_type_c;

    63       if (NULL == singleton)    ERROR;

    63       if (NULL == singleton)    ERROR;

    64       const char *res           = (const char *)symbol->accept(*singleton);

    64       const char *res           = (const char *)symbol->accept(*singleton);

    66       if (NULL == res)          ERROR;

    65       if (NULL == res)          ERROR;

    67       return res;

    66       return res;

    68     }

    67     }

    69     

    68     

    70     /***********************************/

    69     /***********************************/