INF205/lab_3/17_and_18/singly-linked-list.cpp

#include <cstddef>
#include "singly-linked-list.h"

using namespace seq;

// return the size (number of items in the singly linked list)
size_t SinglyLinkedList::size() const
{
   size_t count = 0;
   for(SinglyLinkedListNode* n = this->head; n != nullptr; n = n->get_next()) count++;
   return count;
}

void SinglyLinkedList::enqueue(int value)
{
   SinglyLinkedListNode* new_node = new SinglyLinkedListNode;
   new_node->set_item(value);
   
   if(this->empty()) this->head = new_node;
   else this->tail->set_next(new_node);
   this->tail = new_node;
}

int SinglyLinkedList::dequeue()
{
   if(this->empty()) return 0;  // nothing there to remove
   SinglyLinkedListNode* successor = this->head->get_next();
   int outgoing = this->head->item;
   delete this->head;
   this->head = successor;  // successor of the previous head is the new head
   if(this->head == nullptr) this->tail = nullptr;  // catch special case: the list is now empty
   return outgoing;
}