function yy_shift($yyNewState, $yyMajor, $yypMinor)
    {
        $this->yyidx++;
        if ($this->yyidx >= self::YYSTACKDEPTH) {
            $this->yyidx--;
            if (self::$yyTraceFILE) {
                fprintf(self::$yyTraceFILE, "%sStack Overflow!\n", self::$yyTracePrompt);
            }
            while ($this->yyidx >= 0) {
                $this->yy_pop_parser_stack();
            }
            /* Here code is inserted which will execute if the parser
            ** stack ever overflows */
            return;
        }
        $yytos = new yyStackEntry;
        $yytos->stateno = $yyNewState;
        $yytos->major = $yyMajor;
        $yytos->minor = $yypMinor;
        array_push($this->yystack, $yytos);
        if (self::$yyTraceFILE && $this->yyidx > 0) {
            fprintf(self::$yyTraceFILE, "%sShift %d\n", self::$yyTracePrompt,
                $yyNewState);
            fprintf(self::$yyTraceFILE, "%sStack:", self::$yyTracePrompt);
            for ($i = 1; $i <= $this->yyidx; $i++) {
                fprintf(self::$yyTraceFILE, " %s",
                    self::tokenName($this->yystack[$i]->major));
            }
            fwrite(self::$yyTraceFILE,"\n");
        }
    }