#include <iostream>
#include "SListT.h"
#include <stdexcept>

using namespace std;

struct NodeT {
    ItemT data;
    NodeT * next;
};

ListT::~ListT() {
    NodeT * tmp {head};
    while (tmp != nullptr) {
       tmp = tmp ->next;
       delete head;
       head = tmp;
    }
}

void ListT::PushFront(ItemT newData) {
     NodeT * tmp{new NodeT{newData, head}};
     ++size;
     head = tmp;
     if (nullptr == tail) {
        tail = head;
     }
}

void ListT::PopFront() {
    if (nullptr == head) {
         throw out_of_range{"Attempt to delete an empty list in SListT"};
    } else {
        NodeT * tmp{head};
        head = head->next;
        delete tmp;
        --size;
        if (nullptr == head) {
            tail = nullptr;
        }
    }
}

size_t ListT::Size() const {
    return size;
}

void ListT::Home() {
     ptr = head;
}

bool ListT::Next() {
     if (nullptr == ptr) {
         return false;
     } else {
         ptr = ptr->next;
         return true;
     }
}

bool ListT::AtEnd() {
     return ptr == nullptr;
}

ItemT & ListT::Data() {
     if (nullptr != ptr) {
         return ptr->data;
     } else {
         throw out_of_range{"Attempt to dereference null pointer in SListT"};
     }
}