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#include <iostream>
#include "linkedList.h"
// Purpose: effectively "empties" the list
// Postconditions: current size set to 0, head and tail ptrs set to NULL,
// and all dynamically allocated memory for nodes deallocated
template <typename T>
void LinkedList<T>::clear()
{
while(m_head != NULL)
removeAtHead();
m_size = 0;
}
// Purpose: determines whether x is in the list
// Parameters: x is data value to be found
// Returns: true if x is in the list otherwise, false
template <typename T>
bool LinkedList<T>::find(const T& x) const
{
Node<T> *thisNode;
thisNode = m_head;
while(thisNode != NULL)
{
if(thisNode -> m_data == x)
return true;
}
return false;
}
// Purpose: puts the data value x at the beginning of the list
// Parameters: x is data value to inserted
// Postconditions: current size of list incremented by 1, head pointer
// now points to a node with data value x, the new node's next ptr points
// to what was previously the first in the list, and its prev ptr points
// to NULL if x is the only value in the list, tail pointer also points
// to the new node
template <typename T>
void LinkedList<T>::insertAtHead(const T& x)
{
m_size++;
Node<T> *newNode = new Node<T>;
newNode -> m_data = x;
newNode -> m_next = m_head;
m_head = newNode;
}
// Purpose: puts the data value x at the end of the list
// Parameters: x is data value to inserted
// Postconditions: current size of list incremented by 1, tail pointer
// now points to a node with data value x, the new node's prev ptr points
// to what was previously the last in the list, and its next ptr points
// to NULL if x is the only value in the list, head pointer also points
// to the new node
template <typename T>
void LinkedList<T>::insertAtTail(const T& x)
{
m_size++;
Node<T> *newNode;
newNode -> m_prev = m_tail;
newNode -> m_data = x;
m_tail = newNode;
}
// Purpose: removes the data value at the beginning of the list
// Postconditions: current size of list decremented by 1, head pointer
// now points to whatever the removed node's next ptr was pointing at, and
// that node's prev ptr is NULL if list is now empty, tail pointer
// is set to NULL
// Exceptions: if the list is empty, then throw std::length_error
template <typename T>
void LinkedList<T>::removeAtHead()
{
if(m_size == 0)
throw std::length_error("List is empty");
m_size--;
m_head = m_head -> m_next;
delete m_head -> m_prev;
if(m_size == 0)
m_tail = NULL;
}
// Purpose: removes the data value at the end of the list
// Postconditions: current size of list decremented by 1, tail pointer
// now points to whatever the removed node's prev ptr was pointing at, and
// that node's next ptr is NULL if list is now empty, head pointer
// is set to NULL
// Exceptions: if the list is empty, then throw std::length_error
template <typename T>
void LinkedList<T>::removeAtTail()
{
if (m_size == 0)
{
throw std::length_error("List is empty");
}
m_size--;
m_tail = m_tail -> m_prev;
delete m_tail -> m_next;
if(m_size == 0)
m_head = NULL;
}
// Purpose: starting from the head of the list, removes the first node
// with data value x
// Parameters: x is data value whose first occurrence is to be removed
// Returns: true if an occurrence of x successfully removed otherwise,
// false
// Postconditions: if x was in the list, current size of list decremented
// by 1, and the (formerly) first occurrence of x has been removed
template <typename T>
bool LinkedList<T>::removeFirstOccurrence(const T& x)
{
Node<T> *newNode = m_head;
while(newNode != NULL)
{
if(newNode -> m_data == x)
{
if(newNode != m_head)
newNode -> m_prev -> m_next = newNode -> m_next;
if(newNode != m_tail)
newNode -> m_next -> m_prev = newNode -> m_prev;
m_size--;
delete newNode;
return true;
}
newNode = newNode -> m_next;
}
return false;
}
// Purpose: removes all nodes with data value x
// Parameters: x is data value to be removed
// Returns: # of occurrences of x that were removed (0 if none)
// Postconditions: all occurrence of x have been removed and current size
// of list updated accordingly
template <typename T>
unsigned int LinkedList<T>::removeAllOccurrences(const T& x)
{
int count;
while(removeFirstOccurrence(x))
count++;
return count;
}
// Purpose: performs a deep copy of the data from rhs into this linked list
// Parameters: rhs is linked list to be copied
// Returns: *this
// Postconditions: this list contains same data values (in the same order)
// as are in rhs any memory previously used by this list has been
// deallocated
template <typename T>
LinkedList<T>& LinkedList<T>::operator=(const LinkedList<T>& rhs)
{
if(*this == &rhs)
return *this;
clear();
Node<T> *rhsNode;
*rhsNode = rhs.getHeadPtr();
while(rhsNode != NULL)
{
insertAtTail(rhsNode -> m_data);
rhsNode = rhsNode -> m_next;
}
return *this;
}
// Purpose: determines whether this list is identical to rhs list in
// terms of data values and their order in the list
// Parameters: rhs is list to be compared to this list
// Returns: true if lists are identical otherwise, false
template <typename T>
bool LinkedList<T>::operator==(const LinkedList<T>& rhs) const
{
if(m_size != rhs.size())
return false;
Node<T> *rhsNode = rhs.getHeadPtr();
Node<T> *newNode = m_head;
while(newNode != NULL)
{
if(newNode -> m_data != rhsNode -> m_data)
return false;
}
return true;
}
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