Please help fix this code and add anything to it so that it is not limited: #include

#include

#include

#include "token.h$"$

#include "functions.h$"$

using namespace std;

ifstream ifs; $//$ input file stream used by lexan

SymTab symtab; $//$ global symbol table

Token token; $//$ global token

int lookahead $=0$; $//$ no look ahead token yet

int dbg $=1$; $//$ debut is ON

int main$()$

$\{$

ifs $=$ get$\_$ifs$()$; $//$ open an input file stream w$/$ the program

init$\_$kws$()$; $//$ initialize keywords in the symtab

match$($ lookahead $)$; $//$ get the first input token

prog$()$;

return $0$;

$\}$

$/*$

prog $->$ begin stmt$\_$list end

stmt$\_$list $->$ stmt ; stmt$\_$list

$|$ stmt

$|$ stmt;

stmt $->$ var $=$ expr

var $->$ A $|$ B $|$ C

expr $->$ var $+$ expr

$|$ var $-$ expr

$|$ var

$*/$

void begin$()$

$\{$

match$($ KW $)$;

$\}$

void end$()$

$\{$

match$($ KW $)$;

$\}$

void stmts$()$

$\{$

stmt$()$;

if$($ lookahead $==\text{'}$;$\text{'})$

$\{$

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

stmts$()$;

$\}$

$\}$

void stmt$()$

$\{$

var$()$;

match$(\text{'}=\text{'})$;

expr$()$;

$\}$

void var$()$

$\{$

if$($ lookahead $==$ ID $)$

$\{$

match$($ ID $)$;

$\}$

else

$\{$

error$($ lookahead, ID $)$;

$\}$

$\}$

void expr$()$

$\{$

var$()$;

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

$\{$

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

expr$()$;

$\}$

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

$\{$

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

expr$()$;

$\}$

$\}$

void prog$()$

$\{$

begin$()$;

stmts$()$;

end$()$;

$\}$

$//$ utility methods

void emit$($ int t $)$

$\{$

switch$($ t $)$

$\{$

case $\text{'}+\text{'}$: case $\text{'}-\text{'}$: case $\text{'}=\text{'}$:

cout $<<$ char$($ t $)<<\text{'}\text{'}$;

break;

case $\text{'}$;$\text{'}$:

cout $<<"$;

$"$;

break;

case $\text{'}$

$\text{'}$:

cout $<<"$

$"$;

break;

case ID:

case KW:

case UID:

cout $<<$ symtab.tokstr$($ token.tokvalue$())<<\text{'}\text{'}$;

break;

default:

cout $<<"\text{'}$token $"<<$ t $<<",$ tokvalue $"$

$<<$ token.tokvalue$()<<"\text{'}"$;

break;

$\}$

$\}$

void error$($ int t$,$ int expt, const string &str $)$

$\{$

cerr $<<"$

unexpected token $\text{'}"$;

if$($ lookahead $==$ DONE $)$

$\{$

cerr $<<$ "EOF";

$\}$

else

$\{$

cerr $<<$ token.tokstr$()$;

$\}$

cerr $<<"\text{'}$ of type $"<<$ lookahead;

switch$($ expt $)$

$\{$

case $0$: $//$ default value; nothing to do

break;

case ID:

cout $<<"$ while looking for an ID$"$;

break;

case KW:

cout $<<"$ while looking for KW $\text{'}"<<$ str $<<"\text{'}"$;

break;

default:

cout $<<"$ while looking for $\text{'}"<<$ char$($ expt $)<<"\text{'}"$;

break;

$\}$

cerr $<<"$

syntax error.

$"$;

exit$(1)$;

$\}$

void match$($ int t $)$

$\{$

if$($ lookahead $==$ t $)$

$\{$

token $=$ lexan$()$; $//$ get next token

lookahead $=$ token.toktype$()$; $//$ lookahed contains the tok type

$\}$

else

$\{$

error$($ t $)$;

$\}$

$\}$