case '/':    /* may be division, defined-or, or pattern */
         if ((PL_expect == XOPERATOR || PL_expect == XTERMORDORDOR) && s[1] == '/') {
            ...
            AOPERATOR(DORDOR);
        }
        else if (PL_expect == XOPERATOR) {
            ...
            Mop(OP_DIVIDE);
        }
        else {
            ...
            s = scan_pat(s,OP_MATCH);
        }