Please help me to understand how I can use the add $($enqueue$)$ and remove $($dequeue$)$ in the queue class to fully implement processQueue, as it doesn't work with Queue::iterator it$,$ Request req $=*$it$,$ as they are incompatible. Even though I need to iterate with begin$()$ and end$()$ within the LinkedListcpp.h file.

$--$

Queuecpp.h

#include "Queue.h$"$

$//$template

$//$Queue::Queue$()\{$

$//$ back$=$nullptr;

$//\}$

template

$//$TODO

$//$ add an element t to the end queue

$//$ this should be an O$(1)$ operation

void Queue::add$($T t$)\{$

$//$TODO

ListNode$*$ newNode $=$ new ListNode$($t$)$;

if $($this$->$back $==$ nullptr$)\{$

this$->$front $=$ newNode;

this$->$back $=$ newNode;

$\}$ else $\{$

this$->$back$->$next $=$ newNode;

this$->$back $=$ newNode;

$\}$

$\}$

$//$TODO

$//$remove an element from the front of the queue

$//$ this should be an O$(1)$ operation

template

void Queue::remove$()\{$

$//$TODO

$//$ if queue us empty

$//$ throw new std::string$("$NULL POINTER EXCEPTION QUEUE IS EMPTY

$")$;

if $($this$->$empty$())\{$

throw new std::string$("$NULL POINTER EXCEPTION QUEUE IS EMPTY

$")$;

$\}$

ListNode$*$ temp $=$ this$->$front;

this$->$front $=$ this$->$front$->$next;

delete temp;

$\}$

$--$

Requestcpp.h

#include "Request.h$"$

Request::Request$()\{$

action$=""$;

title$=""$;

singer$=""$;

chartPosition$=-1$;

$\}$

Request::Request$($std::string action,std:: string title,

std::string singer$,$

int chartPosition$)\{$

this$->$title$=$title;

this$->$singer$=$singer;

this$->$action$=$action;

this$->$chartPosition$=$chartPosition;

$\}$

std::string Request::toString$()\{$

return "Action: $"+$action$+"$ Title: $"+$title$+"$ Singer: $"+$singer$+"$ ChartPosition: $"+$std::to$\_$string$($chartPosition$)$;

$\}$

std::string Request::getTitle$()\{$return title;$\}$

std::string Request::getSinger$()\{$return singer;$\}$

std::string Request::getAction$()\{$return action;$\}$

int Request::getChartPosition$()\{$return chartPosition;$\}$

$//$TODO

$//$compares titles and returns true if titles are same using string compare method

bool Request::operator$==($Request other$)\{$

return title.compare$($other$.$getTitle$())==0$;

$\}$

$--$

LinkedListcpp.h

LinkedList::Iterator::Iterator$()\{$

cur$=$nullptr;

$\}$

template

LinkedList::Iterator::Iterator$($ListNode $*$ t$)\{$

cur$=$ t;

$\}$

template

ListNode $*$ LinkedList::Iterator::next$()\{$

return cur$->$next;

$\}$

template

ListNode $*$ LinkedList::Iterator::getCur$()\{$

return cur;

$\}$

template

bool LinkedList::Iterator::operator$==($Iterator iter$)\{$

return cur$==$iter.getCur$()$;

$\}$

template

ListNode LinkedList::Iterator::operator$()\{$

return cur;

$\}$

template

void LinkedList::Iterator::operator$++()\{$

if $($cur$!=$nullptr$)$

cur$=$cur$->$next;

$\}$

template

typename LinkedList::Iterator LinkedList::begin$()\{$

return Iterator$($front$)$;

$\}$

template

typename LinkedList::Iterator LinkedList::end$()\{$

return Iterator$($back$)$;

$\}$

template

bool LinkedList::operator$==($T other$)\{$

return $*$this$==$other;

$\}$

$--$

void processRequest$($LinkedList &list,std::string action, std::string title,std::string singer$,$int chartPos$)\{$

Song s$($title$,$singer$,$chartPos$)$;

char ch $=$action$[0]$;

switch$($ch$)\{$

case $\text{'}$P$\text{'}$ : std::cout$<$ &list $,$Queue& q$)\{$

int requestNumber$=1$;

$//$Create an iterator for the Queue to iteratate through requests

std::cout$<<"-------------------------------------------------------------------------$

$"$;

$//$ call processRequest

std::cout$<<"-------------------------------------------------------------------------$

$"$

std::cout$<<"-------------------------------------------------------------------------$

$"$;

$\}$