405 lines
12 KiB
C++
405 lines
12 KiB
C++
/*#############################################################################
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## Author: Shaun Reed ##
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## Legal: All Content (c) 2020 Shaun Reed, all rights reserved ##
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## About: An example of a circular doubly linked list ##
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## ##
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## Contact: shaunrd0@gmail.com | URL: www.shaunreed.com | GitHub: shaunrd0 ##
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##############################################################################
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## circledoublelist.cpp
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*/
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#include "circledoublelist.h"
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/******************************************************************************
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* Constructors, Destructors, Operators
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*****************************************************************************/
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/** copy constructor
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* @brief Construct a new CircleDoubleList::CircleDoubleList object from an existing one
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*
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* @param rhs CircleDoubleList object
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*/
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CircleDoubleList::CircleDoubleList(const CircleDoubleList& rhs)
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{
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Node *cp = rhs.tail;
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Node *tempHead;
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if (cp == NULL) tail = NULL;
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else {
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tail = new Node(cp->data);
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tempHead = tail;
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while (cp->next != NULL) {
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cp = cp->next;
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tail->next = new Node(cp->data);
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tail = tail->next;
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}
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tail = tempHead;
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}
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}
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/** operator=
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* @brief Assign two CircleDoubleList objects equal using copy constr and class destr
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* Pass the rhs by value to create local copy, swap its contents
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* Destructor called on previous CircleDoubleList data at the end of this scope
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*
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* @param rhs CircleDoubleList object passed by value
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* @return CircleDoubleList A deep copy of the rhs CircleDoubleList object
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*/
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CircleDoubleList CircleDoubleList::operator=(CircleDoubleList rhs)
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{
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if (this != &rhs) return *this;
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std::swap(tail, rhs.tail);
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return *this;
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}
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/** destructor
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* @brief Destroy the CircleDoubleList::CircleDoubleList object
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*/
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CircleDoubleList::~CircleDoubleList()
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{
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makeEmpty();
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}
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/******************************************************************************
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* Public Member Functions
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*****************************************************************************/
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/** insert
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* @brief Inserts a value to the head of our linked list
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*
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* @param val The value to be inserted
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*/
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bool CircleDoubleList::insert(int val)
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{
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bool inserted = insert(val, tail);
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if (inserted)
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std::cout << "[" << val << "] was inserted into the list\n";
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else std::cout << "[" << val << "] could not be inserted into the list\n";
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return inserted;
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}
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/** insert at
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* @brief Inserts a value in the place of a given key
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* Key Node found is moved to the newNode->next positon
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*
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* @param key The value to search for to determine insert location
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* @param val The value to be inserted into the list
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*/
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bool CircleDoubleList::insert(int val, int key)
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{
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// Check that we are not trying to insert at a position within an empty list
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if (tail == NULL) {
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std::cout << "Cannot insert at a key value using an empty list\n";
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return false;
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}
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bool inserted = insert(val, key, tail->next);
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if (inserted)
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std::cout << "[" << val << "] was inserted into the list\n";
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else std::cout << "[" << val << "] could not be inserted into the list\n";
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return inserted;
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}
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/** remove
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* @brief Removes a value in the list by calling overloaded private member and handling output
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*
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* @param val Value to be removed from the list
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* @return true If the value was removed from the list
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* @return false If the value was not removed from the list
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*/
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bool CircleDoubleList::remove(int val)
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{
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// Check that we are not trying to remove from an empty list
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if (isEmpty()) {
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std::cout << "Cannot remove from an empty list\n";
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return false;
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}
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// Attempt to remove the item
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bool removed = remove(val, tail->next);
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if (removed)
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std::cout << "[" << val << "] was removed from the list\n";
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else std::cout << "[" << val << "] could not be removed from the list\n";
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return removed;
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}
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/** replace
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* @brief Replaces a value in the list by calling overloaded private member and handling output
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*
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* @param val Value to insert into the list
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* @param key Value to be replaced within the list
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* @return true If the key has been replaced in the list by val
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* @return false If the key has not been replaced in the list by val
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*/
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bool CircleDoubleList::replace(int val, int key)
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{
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// Check that we are not trying to replace within an empty list
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if (isEmpty()) {
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std::cout << "Cannot replace anything within an empty list\n";
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return false;
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}
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// Attempt to replace the item
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bool replaced = replace(val, key, tail->next);
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if (replaced)
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std::cout << "[" << key << "] was replaced by [" << val << "] in the list\n";
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else std::cout << "[" << key << "] could not be replaced by [" << val << "] in the list\n";
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return replaced;
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}
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/** makeEmpty
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* @brief Empty this CircleDoubleList object, deleting all associated Nodes
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*/
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void CircleDoubleList::makeEmpty()
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{
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Node *nextNode;
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if (isEmpty()) return;
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// Start deletion from the head of the list
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nextNode = tail->next;
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while(!isEmpty()) {
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nextNode = nextNode->next;
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remove(nextNode->prev->data);
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}
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nextNode = NULL;
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return;
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}
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/** isEmpty
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* @brief Determine if the CircleDoubleList is empty
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*
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* @return true If the CircleDoubleList::tail is NULL
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* @return false If the CircleDoubleList::tail contains data
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*/
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bool CircleDoubleList::isEmpty() const
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{
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return tail == NULL;
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}
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/** peek
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* @brief returns the value at the CircleDoubleList::head
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*
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* @return int The value held at the Node pointed to by CircleDoubleList::head
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*/
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int CircleDoubleList::peek() const
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{
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if (!isEmpty())
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std::cout << "[" << tail->next->data << "] is at the top of our list\n";
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else std::cout << "Nothing to peek, our list is empty...\n";
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// If the list has data we return it, otherwise we return the smallest possible int (error)
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return (!isEmpty()) ? tail->data : INT32_MIN;
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}
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/** print
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* @brief Output the data held by the CircleDoubleList object
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* Calls to the private print()
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*/
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void CircleDoubleList::print() const
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{
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// Print from the head of our list
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if(!isEmpty()) print(tail->next);
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else std::cout << "Nothing to print, our list is empty...\n";
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}
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/** find
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* @brief Calls to overloaded private member find() and handles output
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*
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* @param val The value to search for within our CircleDoubleList
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* @return true If the value was found in this CircleDoubleList
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* @return false If the value was not found in this CircleDoubleList
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*/
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bool CircleDoubleList::find(int val) const
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{
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// Check that we are not trying to search an empty list
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if (isEmpty()) {
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std::cout << "Cannot search an empty list\n";
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return false;
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}
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Node *result = find(val, tail);
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if( result == NULL) {
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std::cout << "[" << val << "] Was not found in our list\n";
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return false;
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}
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std::cout << "[" << result->data << "] Was found in our list\n";
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return true;
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}
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/******************************************************************************
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* Private Member Functions
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*****************************************************************************/
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/** insert
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* @brief Private member to handle inserting value into the list
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*
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* @param val Value to be inserted
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* @param tail The tail node of the list to insert the value into
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* @return true If the value was inserted
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* @return false If the value could not be inserted
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*/
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bool CircleDoubleList::insert(int val, Node *&tail)
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{
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Node *newNode = new Node(val);
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if (!isEmpty()) {
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// Relink the current head to the node after newNode
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newNode->next = tail->next;
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tail->next->prev = newNode;
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// Relink our head and tail nodes, making newNode the head node
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tail->next = newNode;
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newNode->prev = tail;
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}
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else tail = newNode;
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return true;
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}
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/** insert at
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* @brief Private member to handle inserting a value at a key within our list
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*
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* @param val Value to be inserted
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* @param key Key value to search for within the list
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* @param head Head node of the list to insert to
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* @return true If the value was inserted
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* @return false If the value was not inserted
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*/
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bool CircleDoubleList::insert(int val, int key, Node *&head)
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{
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Node *newNode = new Node(val);
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// Let insert() handle inserting at the head
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if (head->data == key) return insert(val);
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// Get the node which contains our value
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Node *keyNode = find(key, head);
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// If there was no keyNode found, the key is not in our list, do nothing
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if (keyNode == NULL) return false;
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// Insert the newNode in front of the previous to the keyNode
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// [head]->[key]->[tail]
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// [head]->[new]->[key]->[tail]
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newNode->prev = keyNode->prev;
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keyNode->prev->next = newNode;
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// Change the keyNode->prev ptr to newNode
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newNode->next = keyNode;
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keyNode->prev = newNode;
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return true;
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}
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/** remove
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* @brief Private member to remove values from the list
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*
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* @param val Value to be removed
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* @param head Head of the list to remove the value from
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* @return true If the value has been removed from the list
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* @return false If the value has not been removed from the list
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*/
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bool CircleDoubleList::remove(int val, Node *&head)
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{
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// If there is only one node in the list
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// Synonymous with: if (tail = tail->next)
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if (head == head->next) {
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delete tail;
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tail = NULL;
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// Nothing to relink, list is empty
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return true;
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}
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// If the head node contains the value to remove
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if (head->data == val) {
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Node *temp = head;
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// Move head to the next node in the list
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head = head->next;
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// Relink head and tail nodes
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head->prev = tail;
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tail->next = head;
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// Delete dangling pointer created by relinking
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delete temp;
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return true;
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}
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// If the tail node contains the value to remove
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if (tail->data == val) {
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Node *temp = tail;
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// Move tail to the previous node in the list
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tail = tail->prev;
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// Relink head and tail nodes
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head->prev = tail;
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tail->next = head;
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// Delete dangling pointer created by relinking
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delete temp;
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return true;
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}
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// Search for the value further within our list
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Node *keyNode = find(val, head);
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// If NULL, the value does not exist within our list
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if (keyNode == NULL) return false;
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// Relink surrounding nodes to make keyNode a dangling ptr
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keyNode->next->prev = keyNode->prev;
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keyNode->prev->next = keyNode->next;
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// Delete the dangling node created by relinking above
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delete keyNode;
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keyNode = NULL;
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return true;
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}
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/** replace
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* @brief Private member to replace values within the list
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*
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* @param val Value to insert into the list
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* @param key Value to be replaced within the list
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* @param head Head node of the list to modify
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* @return true If the key has been replaced by val within the list
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* @return false If the key has not been replaced by val within the list
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*/
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bool CircleDoubleList::replace(int val, int key, Node *&head)
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{
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Node *replacee = find(key, head);
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if (replacee == NULL) return false;
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replacee->data = val;
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return true;
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}
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/** find
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* @brief Find and return a Node which contains the given value
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*
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* @param val The value to search for within our CircleDoubleList
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* @param start The node to begin the search from, returns on the first found result
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* @return CircleDoubleList::Node* A pointer to the Node containing the search value
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*/
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CircleDoubleList::Node* CircleDoubleList::find(int val, Node *start) const
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{
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// If given a NULL list, return NULL
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// If given a head which contains the requested value, return the foundNode
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if (start == NULL || start->data == val) return start;
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// Copy our start position, check its value
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Node *foundNode = start;
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if (foundNode->data == val) return foundNode;
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// Keep checking the next node until we reach the start value again
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while (foundNode->next != start) {
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foundNode = foundNode->next;
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if (foundNode->data == val) return foundNode;
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}
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// If we have not yet returned a foundNode, the key is not in our list
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return NULL;
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}
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/** print
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* @brief Output the contents of a CircleDoubleList from the given Node to NULL
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*
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* @param start The Node to begin traversing output from
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*/
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void CircleDoubleList::print(Node *start) const
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{
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Node *temp = start;
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std::cout << "List Contents: " << temp->data << " | ";
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temp = temp->next;
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while (temp != start) {
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std::cout << temp->data << " | ";
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temp = temp->next;
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}
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std::cout << std::endl;
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}
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