// LList.cpp
#include "LList.h"

LList::LList()
{
  head_ = NULL;
  size_ = 0;
}

ListNode* LList::_find(size_t position)
{
  ListNode *node = head_;
  size_t i;

  for (i=0; i<position; i++) {
    node = node->link_;
  }
  return node;
}

ItemType LList::_delete(size_t position)
{
  ListNode *node, *dnode;
  ItemType item;

  if (position == 0) {
    dnode = head_;
    head_ = head_->link_;
    item = dnode->item_;
    delete dnode;
  }
  else {
    node = _find(position - 1);
    if (node != NULL) {
      dnode = node->link_;
      node->link_ = dnode->link_;
      item = dnode->item_;
      delete dnode;
    }
  }
  size_ -= 1;
  return item;
}                

void LList::append(ItemType x)
{
  ListNode *node, *newNode = new ListNode(x);
  
  if (head_ != NULL) {
    node = _find(size_ - 1);
    node->link_ = newNode;
  }
  else {
    head_ = newNode;
  }
  size_ += 1;
}

void LList::insert(size_t i, ItemType x)
{
  ListNode *node;
  
  if (i == 0) {
    head_ = new ListNode(x, head_);
  }
  else {
    node = _find(i - 1);
    node->link_ = new ListNode(x, node->link_);
  }
  size_ += 1;
}

ItemType LList::pop(int i)
{
  if (i == -1) {
    i = size_ - 1;
  }
  return _delete(i);
}

ItemType& LList::operator[](size_t position)
{
  ListNode *node;

  node = _find(position);
  return node->item_;
}

LList::LList(const LList& source)
{
  copy(source);
}

void LList::copy(const LList &source)
{
  ListNode *snode, *node;

  snode = source.head_;
  if (snode) {
    node = head_ = new ListNode(snode->item_);
    snode = snode->link_;
  }
  while (snode) {
    node->link_ = new ListNode(snode->item_);
    node = node->link_;
    snode = snode->link_;
  }
  size_ = source.size_;
}

LList& LList::operator=(const LList& source)
{
  dealloc();
  copy(source);
}

LList::~LList()
{
  dealloc();
}

void LList::dealloc()
{
  ListNode *node, *dnode;

  node = head_;
  while (node) {
    dnode = node;
    node = node->link_;
    delete dnode;
  }
}