regular grammar for this code :

public class RecursiveDescentParser $\{$

private String input;

private int index;

private char inputSymbol;

public RecursiveDescentParser$($String input$)\{$

this.input $=$ input;

this.index $=0$;

this.inputSymbol $=$ input.charAt$($index$)$;

$\}$

private void nextToken$()\{$

index$++$;

if $($index $<$ input.length$())\{$

inputSymbol $=$ input.charAt$($index$)$;

$\}$ else $\{$

inputSymbol $=\text{'}\backslash 0\text{'}$;

$\}$

$\}$

private void expected$($char token$)\{$

if $($inputSymbol $==$ token$)\{$

nextToken$()$;

$\}$ else $\{$

throwError$("$Unexpected symbol: $"+$ inputSymbol$)$;

$\}$

$\}$

private void throwError$($String errorMessage$)\{$

throw new RuntimeException$("$Parsing error: $"+$errorMessage$)$;

$\}$

$//$ E $$ TE$\text{'}$

public void parseE$()\{$

parseT$()$;

parseEPrime$()$;

$\}$

$//$ E$\text{'}+$TE$\text{'}|-$TE$\text{'}|$

private void parseEPrime$()\{$

if $($inputSymbol $==\text{'}+\text{'})\{$

expected$(\text{'}+\text{'})$;

parseT$()$;

parseEPrime$()$;

$\}$ else if $($inputSymbol $==\text{'}-\text{'})\{$

expected$(\text{'}-\text{'})$;

parseT$()$;

parseEPrime$()$;

$\}$

$\}$

$//$ T $$ FT$\text{'}$

private void parseT$()\{$

parseF$()$;

parseTPrime$()$;

$\}$

$//$ T$\text{'}*$FT$\text{'}|/$FT$\text{'}|$

private void parseTPrime$()\{$

if $($inputSymbol $==\text{'}*\text{'})\{$

expected$(\text{'}*\text{'})$;

parseF$()$;

parseTPrime$()$;

$\}$ else if $($inputSymbol $==\text{'}/\text{'})\{$

expected$(\text{'}/\text{'})$;

parseF$()$;

parseTPrime$()$;

$\}$

$\}$

$//$ F $($E$)|$ id

private void parseF$()\{$

if $($Character$.$isDigit$($inputSymbol$))\{//$ Check if it's a digit

parseNumber$()$;

$\}$ else if $($inputSymbol $==\text{'}(\text{'})\{$

expected$(\text{'}(\text{'})$;

parseE$()$;

if $($inputSymbol $==\text{'})\text{'})\{$

expected$(\text{'})\text{'})$;

$\}$ else $\{$

throwError$("\text{'})\text{'}$ expected"$)$;

$\}$

$\}$ else $\{$

throwError$("$Unexpected symbol: $"+$ inputSymbol$)$;

$\}$

$\}$

$//$ Method to parse a number

private void parseNumber$()\{$

while $($Character$.$isDigit$($inputSymbol$))\{$

nextToken$()$;

$\}$

$\}$

public static void main$($String$[]$ args$)\{$

String input$1="(3+5-4)*2/1"$;

String input$2="(3+-5)*2"$;

RecursiveDescentParser parser$1=$ new RecursiveDescentParser$($input$1)$;

RecursiveDescentParser parser$2=$ new RecursiveDescentParser$($input$2)$;

try $\{$

parser$1.$parseE$()$;

System.out.println$("$Parser$1$ is successful!"$)$;

$\}$ catch $($RuntimeException e$)\{$

System.out.println$($e$.$getMessage$())$;

$\}$

try $\{$

parser$2.$parseE$()$;

System.out.println$("$ and Parser$2$ is successful!"$)$;

$\}$ catch $($RuntimeException e$)\{$

System.out.println$($e$.$getMessage$())$;

$\}$

$\}$

$\}$