here is the template for the JLex file: $//$transform the following to A$3.$lex

import java$\_$cup.runtime.$*$;

$\%\%$

$\%$implements java$\_$cup.runtime.Scanner

$\%$type Symbol

$\%$function next$\_$token

$\%$class CalcScanner

$\%$eofval$\{$ return null;

$\%$eofval$\}$

IDENTIFIER $=[$a$-$zA$-$Z$\_][$a$-$zA$-$Z$0-9\_]*$

NUMBER $=[0-9]+$

$\%\%$

$"+"\{$ return new Symbol$($CalcSymbol$.$PLUS$)$; $\}$

$"-"\{$ return new Symbol$($CalcSymbol$.$MINUS$)$; $\}$

$"*"\{$ return new Symbol$($CalcSymbol$.$TIMES$)$; $\}$

$"/"\{$ return new Symbol$($CalcSymbol$.$DIVIDE$)$; $\}$

$\{$NUMBER$\}\{$ return new Symbol$($CalcSymbol$.$N UMBER, new Integer$($yytext$()))$;$\}$

$\backslash$r$|$

$\{\}$

$.\{\}$ here is the starting template for javaCup specification: import java.io$.*$;

$/*$ Terminals $($tokens returned by the scanner$).*/$

terminal PLUS, MINUS, TIMES, DIVIDE, LPAREN, RPAREN;

terminal Integer NUMBER;

$/*$ Non terminals $*/$

non terminal Integer expr;

$/*$ Precedences $*/$

precedence left PLUS, MINUS;

precedence left TIMES, DIVIDE;

$/*$ The rules $*/$

expr ::$=$ expr:e$1$ PLUS expr:e$2\{$: RESULT $=$ new Integer$($e$1.$intValue$()+$ e$2.$intValue$())$;

:$\}$

$|$ expr:e$1$ MINUS expr:e$2\{$: RESULT $=$ new Integer$($e$1.$intValue$()-$ e$2.$intValue$())$;

:$\}$

$|$ expr:e$1$ TIMES expr:e$2\{$: RESULT $=$ new Integer$($e$1.$intValue$()*$ e$2.$intValue$())$;

:$\}$

$|$ expr:e$1$ DIVIDE expr:e$2\{$: RESULT $=$ new Integer$($e$1.$intValue$()/$ e$2.$intValue$())$;

:$\}$

$|$ LPAREN expr:e RPAREN $\{$: RESULT $=$ e;

:$\}$

$|$ NUMBER:e $\{$: RESULT$=$ e; :$\}$

;